1. Safety Precautions and Warnings
To prevent personal injury or damage to vehicles and/or the
scan tool, read this instruction manual first and observe the
following safety precautions at a minimum whenever working
on a vehicle:
Do not attempt to operate or observe the tool while driving a vehicle.
Operating or observing the tool will cause driver distraction and
could cause a fatal accident.
Wear safety eye protection that meets ANSI standards.
Operate the vehicle in a well ventilated work area: Exhaust gases
are Poisonous.
Put the transmission in PARK (for automatic transmission) or
NEUTRAL (for manual transmission) and make sure the parking
brake is engaged.
Keep the scan tool dry, clean, free from oil/water or grease. Use a
mild detergent on a clean cloth to clean the outside of the scan tool,
when Necessary.
Always perform automotive testing in a safe environment
The first generation of On-Board Diagnostics (called OBD I) was developed by
the California Air Resources Board (CARB) and implemented in 1988 to monitor
some of the emission control components on vehicles. 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".
The OBD II system is designed to monitor emission control systems and key
engine components by performing either continuous or periodic tests of specific
components and vehicle conditions. When a problem is detected, the OBD II
2. General Information
2.1 On-Board Diagnostics (OBD) II
system turns on a warning lamp (MIL) on the vehicle instrument panel to alert
the driver typically by the phrase “Check Engine” or “Service Engine Soon”. The
system will also store important information about the detected malfunction so
that a technician can accurately find and fix the problem. Here below follow
three pieces of such valuable Information:
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. OBD II
Diagnostic Trouble Codes consist of a five-digit alphanumeric code. The first
character, a letter, identifies which control system sets the code. The other four
characters, all numbers, provide additional information on where the DTC
originated and the operating conditions that caused it to be set. Below is an
example to illustrate the structure of the digits:
DTC Example
P 0 5 2 0
Systems
B = Body
C = Chassis
P = Powertrain
U = Network
Last two digits identify individual
component within the system
Code Type
Generic (SAE):
P0
B0
C0
U0
Manufacturer Specific:
P1, P2
B1, B2
C1, C2
U1, U2
Sub-systems
1 = Fuel and air metering
2 = Ignition system or engine misfire
3 = Auxiliary emissions controls
4 = Vehicle speed control and idle controls
5 = Computer output circuits
6 = Transmission controls
Figure 1-2: Explanation of a diagnostic trouble code.
