Launch Creader 629 User manual

V1.00.001
05-27-2020

LAUNCH 629 User's Manual
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Copyright Information
Copyright © 2020 by LAUNCH TECH CO., LTD. All rights reserved. No part of
this publication may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying and
recording or otherwise, without the prior written permission of LAUNCH. The
information contained herein is designed only for the use of this unit. LAUNCH
is not responsible for any use of this information as applied to other units.
Statement: LAUNCH owns the complete intellectual property rights for the software
used by this product. For any reverse engineering or cracking actions against the
software, LAUNCH will block the use of this product and reserve the right to pursue
their legal liabilities.
Trademark Information
LAUNCH is a registered trademark of LAUNCH TECH CO., LTD. (also
called LAUNCH for short) in China and other countries. All other LAUNCH
trademarks, service marks, domain names, logos, and company names
referred to in this manual are either trademarks, registered trademarks,
service marks, domain names, logos, company names of or are otherwise
the property of LAUNCH or its affiliates. In countries where any of the
LAUNCH trademarks, service marks, domain names, logos and company
names are not registered, LAUNCH claims other rights associated with
unregistered trademarks, service marks, domain names, logos, and company
names. Other products or company names referred to in this manual may
be trademarks of their respective owners. You may not use any trademark,
service mark, domain name, logo, or company name of LAUNCH or any third
party without permission from the owner of the applicable trademark, service
mark, domain name, logo, or company name. You may contact LAUNCH by
visiting the website at www.cnlaunch.com, or writing to LAUNCH TECH. CO.,
LTD., Launch Industrial Park, North of Wuhe Avenue, Banxuegang, Bantian,
Longgang, Shenzhen, Guangdong, P.R.China, to request written permission to
use Materials on this manual for purposes or for all other questions relating to
this manual.
SAFETY PRECAUTIONS AND WARNINGS
To prevent personal injury or damage to vehicles and/or the test equipment,
please read this user’s manual rst carefully and observe the following safety
precautions at a minimum whenever working on a vehicle:
• Always perform automotive testing in a safe environment.
• Do not attempt to operate or observe the tool while driving a vehicle.

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Operating or observing the tool will cause driver distraction and could cause
a fatal accident.
• Wear safety eye protection that meets ANSI standards.
• Keep clothing, hair, hands, tools, test equipment, etc. away from all moving
or hot engine parts.
• Operate the vehicle in a well-ventilated work area: Exhaust gases are
poisonous.
• Put blocks in front of the drive wheels and never leave the vehicle
unattended while running tests.
• Use extreme caution when working around the ignition coil, distributor
cap, ignition wires and spark plugs. These components create hazardous
voltages when the engine is running.
• Put the transmission in P (for A/T) or N (for M/T) and make sure the parking
brake is engaged.
• Keep a fire extinguisher suitable for gasoline/chemical/ electrical fires
nearby.
• Don’t connect or disconnect any test equipment while the ignition is on or
the engine is running.
• Keep the test equipment dry, clean, free from oil/water or grease. Use a mild
detergent on a clean cloth to clean the outside of the test equipment, when
necessary.
FCC Statement
This device complies with Part 15 of the FCC Rules. Operation is subject to
the following two conditions:
(1) This device may not cause harmful interference, and
(2) This device must accept any interference received, including interference
that may cause undesired operation.

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Table of Contents
1. Introduction.................................................................................................1
2. General Information-About OBDII/EOBD .................................................3
2.1 On-Board Diagnostics (OBD) I ...................................................................3
2.2 On-Board Diagnostics (OBD) II ..................................................................3
2.3 Diagnostic Trouble Codes (DTCs)..............................................................5
2.4 Location of the Data Link Connector (DLC)................................................6
2.5 OBD II Terminology ....................................................................................7
2.6 OBD II Monitors..........................................................................................9
2.6.1 Continuous Monitors..........................................................................9
2.6.2 Non-Continuous Monitors................................................................11
2.6.3 OBD II Reference Table...................................................................14
2.7 DTCs and MIL Status ...............................................................................16
3. Product Descriptions ...............................................................................18
3.1 General Controls ......................................................................................18
3.2 Specications ...........................................................................................20
3.3 Accessories ..............................................................................................21
4. Initial Use...................................................................................................22
4.1 Connection ...............................................................................................22
4.2 Main Menu................................................................................................23
4.3 Settings.....................................................................................................24
5. Diagnose ...................................................................................................25
5.1 OBDII/EOBD Diagnosing..........................................................................25
5.2 System Diagnosing...................................................................................31
5.3 Service......................................................................................................32
5.4 Review......................................................................................................33
5.5 DTC Lookup .............................................................................................33
6. Print ...........................................................................................................35
7. Help............................................................................................................38

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7.1 DLC Location Information.........................................................................38
7.2 Abbreviation..............................................................................................38
7.3 Tool Information ........................................................................................38
7.4 About OBD................................................................................................39
7.5 Upgrade Information.................................................................................39
8. Register & Update ....................................................................................40
9. FAQ ............................................................................................................43

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1. Introduction
This OBD II scanner is specially developed by LAUNCH, which supports all 10
modes of OBD II test for a complete diagnosis. Featuring the 3.5” TFT color
display, it enables users to read/clear DTCs, record, save and playback data
in live graphic display. It is also very easy to use. With built-in help menus and
code denitions, diagnosing and repairing that dreaded Check Engine Light is
now easier than ever!
This code reader will preform the following functions:
• Read dynamic data streams and MIL
• Read readiness status
• Freeze frame data
• Read current DTCs
• Read pending DTCs
• Read permanent DTCs
• Clear DTCs
• O2sensor test
• On-board monitor test
• Read vehicle information
• OBD II data record and replay
• Print data via PC
Moreover, it can be updated via memory card to keep synchronized with the
latest available software version.
Note: This tool may automacally reset while being disturbed by strong stac
electricity. THIS IS A NORMAL REACTION.
This tool is specially designed to work with all OBD II compliant vehicles,
including Controller Area Network (CAN). It is required by EPA that all 1996
and newer vehicles (cars and light trucks) sold in the United States must be
OBD II compliant and this includes all American, Asian and European vehicles.
A small number of 1994 and 1995 model year gasoline vehicles are OBD II
compliant. To verify if a 1994 or 1995 vehicle is OBD II compliant, check the
following:
1. Vehicle Emissions Control Information (VECI) Label. It is located
under the hood or by the radiator of most vehicles. If the vehicle is OBD II

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compliant, the label will designate “OBD II Certied”.
2. Government regulations mandate that all OBD II compliant vehicles must
have a “common” 16-pin Data Link Connector (DLC).
Note: Some 1994 and 1995 vehicles have 16-pin connectors but are not OBD II
compliant. Only those vehicles with a Vehicle Emissions Control Label stang “OBD
II Cered” are OBD II compliant.

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2. General Information-About OBDII/EOBD
2.1 On-Board Diagnostics (OBD) I
Note: With the exception of some 1994 and 1995 vehicles, most vehicles
from 1982 to 1995 are equipped with some type of first generation On-Board
Diagnoscs.
Beginning in 1988, California’s Air Resources Board (CARB), and later the
Environmental Protection Agency (EPA) required vehicle manufacturers to
include a self-diagnostic program in their on-board computers. The program
would be capable of identifying emissions-related faults in a system. The rst
generation of Onboard Diagnostics came to be known as OBD I.
OBD I is a set of self-testing and diagnostic instructions programmed into
the vehicle’s onboard computer. The programs are specifically designed to
detect failures in the sensors, actuators, switches and wiring of the various
vehicle emissions-related systems. If the computer detects a failure in any of
these components or systems, it lights an indicator on the dashboard to alert
the driver. The indicator lights only when an emissions-related problem is
detected.
The computer also assigns a numeric code for each specic problem that it
detects, and stores these codes in its memory for later retrieval. These codes
can be retrieved from the computer’s memory with the use of a “Code Reader”
or a “Diagnostic Tool.”
2.2 On-Board Diagnostics (OBD) II
As technology evolved and the desire to improve the On-Board Diagnostic
system increased, a new generation of On-Board Diagnostic system was
developed. This second generation of On-Board Diagnostic regulations is
called “OBD II”.
In addition to performing all the functions of the OBD I System, the OBD II
System has been enhanced with new Diagnostic Programs. These programs
closely monitor the functions of various emissions-related components and
systems (as well as other systems) and make this information readily available
(with the proper equipment) to the technician for evaluation.
The California Air Resources Board (CARB) conducted studies on OBD I
equipped vehicles. The information that was gathered from these studies

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showed the following:
• A large number of vehicles had deteriorating or degraded emissions-related
components. These components were causing an increase in emissions.
• Because OBD I systems only detect failed components, the degraded
components were not setting codes.
• Some emissions problems related to degraded components only occur
when the vehicle is being driven under a load. The emission checks
being conducted at the time were not performed under simulated driving
conditions. As a result, a significant number of vehicles with degraded
components were passing Emissions Tests.
• Codes, code denitions, diagnostic connectors, communication protocols
and emissions terminology were different for each manufacturer. This
caused confusion for the technicians working on different make and model
vehicles.
To address the problems made evident by this study, CARB and the EPA
passed new laws and standardization requirements. These laws required
that vehicle manufacturers to equip their new vehicles with devices capable
of meeting all of the new emissions standards and regulations. It was also
decided that an enhanced on-board diagnostic system, capable of addressing
all of these problems, was needed. This new system is known as “On-
Board Diagnostics Generation Two (OBD II/OBD 2).” The primary objective
of the OBD II system is to comply with the latest regulations and emissions
standards established by CARB and the EPA.
The Main Objectives of the OBD II System are:
• To detect degraded and/or failed emissions-related components or systems
that could cause tailpipe emissions to exceed by 1.5 times the Federal Test
Procedure (FTP) standard.
• To expand emissions-related system monitoring. This includes a set of
computer run diagnostics called Monitors. Monitors perform diagnostics
and testing to verify that all emissions-related components and/or systems
are operating correctly and within the manufacturer’s specications.
• To use a standardized Diagnostic Link Connector (DLC) in all vehicles.
(Before OBD II, DLCs were of different shapes and sizes.)
• To standardize the code numbers, code denitions and language used to
describe faults. (Before OBD II, each vehicle manufacturer used their own
code numbers, code denitions and language to describe the same faults.)
• To expand the operation of the Malfunction Indicator Lamp (MIL).

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• To standardize communication procedures and protocols between the
diagnostic equipment (Diagnostic Tools, Code Readers, etc.) and the
vehicle’s on-board computer.
2.3 Diagnostic Trouble Codes (DTCs)
OBD II Diagnostic Trouble Codes are codes that are stored by the on-board
computer diagnostic system in response to a problem found in the vehicle.
These codes identify a particular problem area and are intended to provide
you with a guide as to where a fault might be occurring within a vehicle. DO
NOT replace parts based only on DTCs without rst consulting the vehicle’s
service manual for proper testing procedures for that particular system, circuit
or component.
OBD II Diagnostic Trouble Codes consist of a ve-digit alphanumeric code.
• The 1st character is a letter (B, C, P or U). It identies the “main system”
where the fault occurred (Body, Chassis, Powertrain, or Network).
• The 2nd character is a numeric digit (0 thru 3). It identies the “type” of
code (Generic or Manufacturer-Specic).
Generic DTCs are codes that are used by all vehicle manufacturers. The
standards for generic DTCs, as well as their definitions, are set by the Society of
Automotive Engineers (SAE).
Manufacturer-Specific DTCs are codes that are controlled by the vehicle
manufacturers. The Federal Government does not require vehicle
manufacturers to go beyond the standardized generic DTCs in order to comply
with the new OBD II emissions standards. However, manufacturers are free
to expand beyond the standardized codes to make their systems easier to
diagnose.
• The 3rd character is a letter or a numeric digit (0 thru 9, A thru F). It
identies the specic system or sub-system where the problem is located.
• The 4th and 5th characters are letters or numeric digits (0 thru 9, A thru
F). They identify the section of the system that is malfunctioning.

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P0201 - Injector circuit malfunction, Cylinder 1
2.4 Location of the Data Link Connector (DLC)
The DLC (Data Link Connector or Diagnostic Link Connector) is the
standardized 16-cavity connector where diagnostic code readers interface with
the vehicle’s on-board computer. The DLC is usually located 12 inches from
the center of the instrument panel (dash), under or around the driver’s side for

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most vehicles. If Data Link Connector is not located under dashboard, a label
should be there telling location. For some Asian and European vehicles, the
DLC is located behind the ashtray and the ashtray must be removed to access
the connector. If the DLC cannot be found, refer to the vehicle’s service
manual for the location.
2.5 OBD II Terminology
The following terms and their definitions are related to OBD II systems.
Read and reference this list as needed to aid in the understanding of OBD II
systems.
Powertrain Control Module (PCM) -- The PCM is the OBD II accepted term
for the vehicle’s “on-board computer.” In addition to controlling the engine
management and emissions systems, the PCM also participates in controlling
the powertrain (transmission) operation. Most PCMs also have the ability to
communicate with other computers on the vehicle (ABS, ride control, body,
etc.).
Monitors -- Monitors are “diagnostic routines” programmed into the PCM. The
PCM utilizes these programs to run diagnostic tests, and to monitor operation
of the vehicle’s emissions-related components or systems to ensure they
are operating correctly and within the vehicle’s manufacturer specifications.
Currently, up to fifteen Monitors are used in OBD II systems. Additional
Monitors will be added as the OBD II system is further developed.
Note: Not all vehicles support all een Monitors.
Enabling Criteria -- Also termed Enabling Conditions. They are the vehicle-

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specific events or conditions that must occur within the engine before the
various monitors will set, or run. Some monitors require the vehicle to follow
a prescribed “drive cycle” routine as part of the enabling criteria. Drive cycles
vary among vehicles and for each monitor in any particular vehicle. Please
refer to the vehicle’s factory service manual for specic enabling procedures.
Trip - A Trip for a particular Monitor requires that the vehicle is being driven
in such a way that all the required “Enabling Criteria” for the Monitor to run
and complete its diagnostic testing are met. The “Trip Drive Cycle” for a
particular Monitor begins when the ignition key is turned “On.” It is successfully
completed when all the “Enabling Criteria” for the Monitor to run and complete
its diagnostic testing are met by the time the ignition key is turned “Off.” Since
each of the fteen monitors is designed to run diagnostics and testing on a
different part of the engine or emissions system, the “Trip Drive Cycle” needed
for each individual Monitor to run and complete varies.
OBD II Drive Cycle -- A specific mode of vehicle operation that provides
conditions required to set all the readiness monitors applicable to the vehicle
to the “ready” condition. The purpose of completing an OBD II drive cycle is
to force the vehicle to run its onboard diagnostics. Some form of a drive cycle
needs to be performed after DTCs have been erased from the PCM’s memory
or after the battery has been disconnected. Running through a vehicle’s
complete drive cycle will “set” the readiness monitors so that future faults can
be detected. Drive cycles vary depending on the vehicle and the monitor that
needs to be reset. For vehicle specic drive cycle, consult the service manual.
Note: Do not confuse a “Trip” Drive Cycle with an OBD II Drive Cycle. A “Trip”
Drive Cycle provides the “Enabling Criteria” for one specic Monitor to run and
complete its diagnostic testing. An OBD II Drive Cycle must meet the “Enabling
Criteria” for all Monitors on a particular vehicle to run and complete their
diagnosc tesng.
Warm-up Cycle - Vehicle operation after an engine off period where engine
temperature rises at least 40°F (22°C) from its temperature before starting,
and reaches at least 160°F (70°C). The PCM uses warm-up cycles as a
counter to automatically erase a specific code and related data from its
memory. When no faults related to the original problem are detected within a
specied number of warm-up cycles, the code is erased automatically.
Fuel Trim (FT) - Feedback adjustments to the base fuel schedule. Short-term
fuel trim refers to dynamic or instantaneous adjustments. Long-term fuel trim

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refers to much more gradual adjustments to the fuel calibration schedule than
short-term trim adjustments. These long-term adjustments compensate for
vehicle differences and gradual changes that occur over time.
2.6 OBD II Monitors
An important part of a vehicle’s OBD II system is the Readiness Monitors,
which are indicators used to nd out if all of the emissions components have
been evaluated by the OBD II system. They are running periodic tests on
specic systems and components to ensure that they are performing within
allowable limits.
Monitor operation is either “Continuous” or “Non-Continuous,” depending on
the specic monitor.
2.6.1 Continuous Monitors
Some of the vehicle components or systems are continuously tested by the
vehicle’s OBD II system, while others are tested only under specic vehicle
operating conditions. The continuously monitored components listed below are
always ready:
1. Misre Monitor
This Monitor continuously checks for engine misres. A misre occurs when
the air-fuel mixture in the cylinder does not ignite. The misre Monitor uses
changes in crankshaft speed to sense an engine misfire. When a cylinder
misres, it no longer contributes to the speed of the engine, and engine speed
decreases each time the affected cylinder(s) misfire. The misfire Monitor
is designed to sense engine speed fluctuations and determine from which
cylinder(s) the misre is coming, as well as how bad the misre is.
There are three types of engine misres, Types 1, 2, and 3.
• Type 1 and Type 3 misres are two-trip monitor faults. If a fault is sensed
on the rst trip, the computer temporarily saves the fault in its memory as
a Pending Code. The MIL is not commanded on at this time. If the fault is
found again on the second trip, under similar conditions of engine speed,
load and temperature, the computer commands the MIL “On,” and the code
is saved in its long term memory.
• Type 2 misres are the most severe type of misre. When a Type 2 misre
is sensed on the rst trip, the computer commands the MIL to light when
the misre is sensed. If the computer determines that a Type 2 misre is
severe, and may cause catalytic converter damage, it commands the MIL

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to “flash” once per second as soon as the misfire is sensed. When the
misre is no longer present, the MIL reverts to steady “On” condition.
The Misfire Monitor is supported by both “spark ignition” vehicles and
“compression ignition” vehicles.
2. Fuel System Monitor
This Monitor uses a Fuel System Correction program, called Fuel Trim, inside
the on-board computer. Fuel Trim is a set of positive and negative values that
represent adding or subtracting fuel from the engine. This program is used
to correct for a lean (too much air/not enough fuel) or rich (too much fuel/not
enough air) air-fuel mixture. The program is designed to add or subtract fuel,
as needed, up to a certain percent. If the correction needed is too large and
exceeds the time and percent allowed by the program, a fault is indicated by
the computer.
The Fuel System Monitor is supported by both “spark ignition” vehicles and
“compression ignition” vehicles. The Fuel System Monitor may be a “One-Trip”
or “Two-Trip” Monitor, depending on the severity of the problem.
3. Comprehensive Components Monitor (CCM)
This Monitor continuously checks all inputs and outputs from sensors,
actuators, switches and other devices that provide a signal to the computer.
The Monitor checks for shorts, opens, out of range value, functionality and
“rationality* (See Note).”
Raonality: Each input signal is compared against all other inputs and against
informaon in the computer’s memory to see if it makes sense under the current
operang condions.
Example: The signal from the throttle position sensor indicates the vehicle is
in a wide-open throttle condition, but the vehicle is really at idle, and the idle
condion is conrmed by the signals from all other sensors. Based on the input
data, the computer determines that the signal from the throle posion sensor
is not raonal (does not make sense when compared to the other inputs). In this
case, the signal would fail the raonality test.
The CCM is supported by both “spark ignition” vehicles and “compression
ignition” vehicles. The CCM may be either a “One-Trip” or a “Two-Trip”
Monitor, depending on the component.
2.6.2 Non-Continuous Monitors
“Non-continuous” Monitors perform and complete their testing once per trip.

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The “non-continuous” Monitors are:
1. O2Sensor Monitor
The Oxygen Sensor monitors how much oxygen is in the vehicle’s exhaust. It
generates a varying voltage of up to one volt, based on how much oxygen is
in the exhaust gas, and sends the signal to the computer. The computer uses
this signal to make corrections to the air/fuel mixture. If the exhaust gas has a
large amount of oxygen (a lean air/fuel mixture), the oxygen sensor generates
a “low” voltage signal. If the exhaust gas has very little oxygen (a rich mixture
condition), the oxygen sensor generates a “high” voltage signal. A 450mV
signal indicates the most efficient, and least polluting, air/fuel ratio of 14.7
parts of air to one part of fuel.
The oxygen sensor must reach a temperature of at least 600-650°F, and the
engine must reach normal operating temperature, for the computer to enter
into closed-loop operation.
The oxygen sensor only functions when the computer is in closed-loop. A
properly operating oxygen sensor reacts quickly to any change in oxygen
content in the exhaust stream. A faulty oxygen sensor reacts slowly, or its
voltage signal is weak or missing.
The Oxygen Sensor Monitor is supported by “spark ignition” vehicles only.
The Oxygen Sensor Monitor is a “Two-Trip” monitor. If a fault is found on the
rst trip, the computer temporarily saves the fault in its memory as a Pending
Code. The computer does not command the MIL on at this time. If the fault is
sensed again on the second trip, the computer commands the MIL “On,” and
saves the code in its long-term memory.
2. O2Sensor Heater Monitor
The Oxygen Sensor Heater Monitor tests the operation of the oxygen sensor’s
heater. There are two modes of operation on a computer-controlled vehicle:
“open-loop” and “closed-loop.” The vehicle operates in open-loop when the
engine is cold, before it reaches normal operating temperature. The vehicle
also goes to open-loop mode at other times, such as heavy load and full
throttle conditions. When the vehicle is running in open-loop, the oxygen
sensor signal is ignored by the computer for air/fuel mixture corrections.
Engine efficiency during open-loop operation is very low, and results in the
production of more vehicle emissions.
Closed-loop operation is the best condition for both vehicle emissions and
vehicle operation. When the vehicle is operating in closed-loop, the computer
uses the oxygen sensor signal for air/fuel mixture corrections.

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In order for the computer to enter closed-loop operation, the oxygen sensor
must reach a temperature of at least 600°F. The oxygen sensor heater helps
the oxygen sensor reach and maintain its minimum operating temperature
(600°F) more quickly, to bring the vehicle into closed-loop operation as soon
as possible.
The Oxygen Sensor Heater Monitor is supported by “spark ignition” vehicles
only. The Oxygen Sensor Heater Monitor is a “Two-Trip” Monitor. If a fault is
found on the rst trip, the computer temporarily saves the fault in its memory
as a Pending Code. The computer does not command the MIL on at this time.
If the fault is sensed again on the second trip, the computer commands the
MIL “On,” and saves the code in its long-term memory.
3. Catalyst Monitor
The catalytic converter is a device that is installed downstream of the exhaust
manifold. It helps to oxidize (burn) the unburned fuel (hydrocarbons) and
partially burned fuel (carbon monoxide) left over from the combustion process.
To accomplish this, heat and catalyst materials inside the converter react
with the exhaust gases to burn the remaining fuel. Some materials inside
the catalytic converter also have the ability to store oxygen, and release it
as needed to oxidize hydrocarbons and carbon monoxide. In the process,
it reduces vehicle emissions by converting the polluting gases into carbon
dioxide and water.
The computer checks the efciency of the catalytic converter by monitoring the
oxygen sensors used by the system. One sensor is located before (upstream
of) the converter; the other is located after (downstream of) the converter. If
the catalytic converter loses its ability to store oxygen, the downstream sensor
signal voltage becomes almost the same as the upstream sensor signal. In
this case, the monitor fails the test.
The Catalyst Monitor is supported by “spark ignition” vehicles only. The
Catalyst Monitor is a “Two-Trip” Monitor. If a fault is found on the rst trip, the
computer temporarily saves the fault in its memory as a Pending Code. The
computer does not command the MIL on at this time. If the fault is sensed
again on the second trip, the computer commands the MIL “On” and saves the
code in its long-term memory.
4. Heated Catalyst Monitor
Operation of the “heated” catalytic converter is similar to the catalytic
converter. The main difference is that a heater is added to bring the catalytic
converter to its operating temperature more quickly. This helps reduce
emissions by reducing the converter’s down time when the engine is cold. The

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Heated Catalyst Monitor performs the same diagnostic tests as the catalyst
Monitor, and also tests the catalytic converter’s heater for proper operation.
The Heated Catalyst Monitor is supported by “spark ignition” vehicles only.
This Monitor is also a “Two-Trip” Monitor.
5. EGR (Exhaust Gas Recirculation) System Monitor
The Exhaust Gas Recirculation (EGR) system helps reduce the formation
of Oxides of Nitrogen during combustion. Temperatures above 2500°F
cause nitrogen and oxygen to combine and form Oxides of Nitrogen in
the combustion chamber. To reduce the formation of Oxides of Nitrogen,
combustion temperatures must be kept below 2500°F. The EGR system
recirculates small amounts of exhaust gas back into the intake manifold,
where it is mixed with the incoming air/fuel mixture. This reduces combustion
temperatures by up to 500°F. The computer determines when, for how long,
and how much exhaust gas is recirculated back to the intake manifold. The
EGR Monitor performs EGR system function tests at preset times during
vehicle operation.
The EGR Monitor is supported by both “spark ignition” vehicles and
“compression ignition” vehicles. The EGR Monitor is a “Two-Trip” Monitor. If
a fault is found on the first trip, the computer temporarily saves the fault in
its memory as a Pending Code. The computer does not command the MIL
on at this time. If the fault is sensed again on the second trip, the computer
commands the MIL “On,” and saves the code in its long-term memory.
6. EVAP System Monitor
OBD II vehicles are equipped with a fuel Evaporative system (EVAP) that
helps prevent fuel vapors from evaporating into the air. The EVAP system
carries fumes from the fuel tank to the engine where they are burned during
combustion. The EVAP system may consist of a charcoal canister, fuel tank
cap, purge solenoid, vent solenoid, ow monitor, leak detector and connecting
tubes, lines and hoses.
Fumes are carried from the fuel tank to the charcoal canister by hoses or
tubes. The fumes are stored in the charcoal canister. The computer controls
the ow of fuel vapors from the charcoal canister to the engine via a purge
solenoid. The computer energizes or deenergizes the purge solenoid
(depending on solenoid design). The purge solenoid opens a valve to allow
engine vacuum to draw the fuel vapors from the canister into the engine where
the vapors are burned. The EVAP Monitor checks for proper fuel vapor ow to
the engine, and pressurizes the system to test for leaks. The computer runs

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this Monitor once per trip.
The EVAP Monitor is supported by “spark ignition” vehicles only. The EVAP
Monitor is a “Two-Trip” Monitor. If a fault is found on the rst trip, the computer
temporarily saves the fault in its memory as a Pending Code. The computer
does not command the MIL on at this time. If the fault is sensed again on the
second trip, the PCM commands the MIL “On,” and saves the code in its long-
term memory.
7. Secondary Air System Monitor
When a cold engine is rst started, it runs in open-loop mode. During open-
loop operation, the engine usually runs rich. A vehicle running rich wastes
fuel and creates increased emissions, such as carbon monoxide and some
hydrocarbons. A Secondary Air System injects air into the exhaust stream to
aid catalytic converter operation:
• It supplies the catalytic converter with the oxygen it needs to oxidize the
carbon monoxide and hydrocarbons left over from the combustion process
during engine warmup.
• The extra oxygen injected into the exhaust stream also helps the catalytic
converter reach operating temperature more quickly during warm-up
periods. The catalytic converter must heat to operating temperature to work
properly.
The Secondary Air System Monitor checks for component integrity and system
operation, and tests for faults in the system. The computer runs this Monitor
once per trip.
The Secondary Air System Monitor is a “Two-Trip” monitor. If a fault is found
on the rst trip, the computer temporarily saves this fault in its memory as a
Pending Code. The computer does not command the MIL on at this time. If the
fault is sensed again on the second trip, the computer commands the MIL “On,”
and saves the code in its long-term memory.
2.6.3 OBD II Reference Table
The table below lists current OBD II Monitors, and indicates the following for
each Monitor:
A. Monitor Type (how often does the Monitor run; Continuous or Once per
trip).
B. Number of trips needed, with a fault present, to set a pending DTC.
C. Number of consecutive trips needed, with a fault present, to command the
MIL “On” and store a DTC.

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D. Number of trips needed, with no faults present, to erase a Pending DTC.
E. Number and type of trips or drive cycles needed, with no faults present, to
turn off the MIL.
F. Number of warm-up periods needed to erase the DTC from the computer’s
memory after the MIL is turned off.
Name of
Monitor A B C D E F
CCM Continuous 1 2 1 3 40
Misre Monitor
(Type 1 and 3) Continuous 1 2 1 3 - similar
conditions 80
Misre Monitor
(Type 2) Continuous 1 1 1 3 - similar
conditions 80
Fuel System
Monitor Continuous 1 1 or 2 1 3 - similar
conditions 80
Catalytic
Converter
Monitor
Once per trip 1 2 1 3 trips 40
O2 Sensor
Monitor Once per trip 1 2 1 3 trips 40
O2 Sensor
Heater Monitor Once per trip 1 2 1 3 trips 40
EGR Monitor Once per trip 1 2 1 3 trips 40
EVAP system
Monitor Once per trip 1 2 1 3 trips 40
Secondary Air
System
Monitor
Once per trip 1 2 1 3 trips 40
2.7 DTCs and MIL Status
When the vehicle’s on-board computer detects a failure in an emissions-