Service Manual 1000850# 1000851# 20-08-14.doc Page 10 of 15
TROUBLESHOOTING –LCD DIAGNOSTIC GUIDE:
The Jet 6 uses an electronic diagnostic system to help determine faults. If an error is
detected a message is displayed through the LCD screen.
THERMISTOR ERROR
Electronic check:
This indicates that the thermistor is possibly measuring such a large resistance
that it assumes the thermistor circuit is open.
This indicates that the thermistor is possibly measuring zero resistance. It
assumes the thermistor has failed sort circuit.
The element and inlet valve are turned OFF when this error is detected
This is a recoverable error. When the correct range of resistance is measured,
normal operation resumes
Probable causes:
1. The thermistor probe is unplugged from the 4way connector on the PCB or the
thermistor has failed open circuit.
2. The thermistor has failed in a closed circuit manner.
Action required:
1. Check that the thermistor is plugged in to the PCB correctly. If it is, replace the
thermistor.
OVERFILL ERROR
Electronic check:
This indicates that the overflow water level probe has been reached
The element and inlet valve are turned OFF when this error is detected
This is a recoverable error. When the water drops off the overflow water level
probe, normal operation resumes.
Probable causes:
1. The machine is wired incorrectly, e.g. the high level probe wire is connected to the
overflow probe.
2. The tank has overfilled since the inlet solenoid has failed or is “weeping”. If the
machine is turned off for a long time but still plumbed in this can cause it to fill.
3. The high level probe may have become coated in limescale and is allowing too much
water in before it registers to stop.
4. If a brew is cancelled water circulating in the plumbing will return to the tank and
possibly cause it to reach the low level probe (this is also more likely if the high level
probe is scaled up)
5. Bubbles from the element can cause splashing inside the small tank which can trigger
the overflow probe momentarily.
Action required:
1. Dispense some water via the hot water outlet and see if the problem recurs.
2. Descale the tank paying special attention to the high level probe.
3. Check water pressure, if it is too low the solenoid may allow small amounts of water
in.
4. Check the solenoid for debris which may cause it to jam partially open.
