Repair manual

32
Fault code Cause
Fault Description • Remedial measures
039 Vehicle blower control - short circuit Black 1 mm² cable from the 18-pin control unit connector, compartment
6 to the 8-pin cable harness connector, compartment 7, and from there to
the blower relay has short-circuit.
• Check lead and connections and, if necessary, eliminate short circuit.
• Check mounting of the relay.
• Replace relay.
• If the fault could not be eliminated by taking the remedial measures listed
above, then replace control unit.
044 Water pump - relay coil open circuit • Check mounting of the relay on the control unit.
045 Water pump - relay coil short circuit • Replace relay.
• If the fault could not be eliminated by taking the remedial measures listed
above, then replace control unit.
046 Solenoid valve - open circuit "Solenoid valve" cable section from the control unit (connector position “D”)
to the solenoid valve has open circuit or ground leakage.
• Check leads and connections to solenoid valve, if necessary eliminate
ground leakage.
• Replace solenoid valve coil.
• If the fault could not be eliminated by taking the remedial measures listed
above, then replace control unit.
047 Solenoid valve - short circuit “Solenoid valve” cable section from the control unit (connector position “D”)
to the solenoid valve has short-circuit.
• Check leads and connections to solenoid valve, if necessary eliminate
short circuit.
• Replace solenoid valve coil.
• If the fault could not be eliminated by taking the remedial measures listed
above, then replace control unit.
048 Nozzle holder heater - • Check mounting of the relay on the control unit.
relay coil open circuit • Replace relay.
049 Nozzle holder heater -
relay coil short circuit
050 Operation disable - control unit is locked The control unit remains locked through 10 attempts at start-up without
flame detection.
Control unit unlocked by clearing the fault memory with modular timer,
diagnostic unit or KD 2000 (see pages 26 to 29).
• For remedial measures, see fault code 052.
051 Flame monitor reports • Replace burner.
"Flamme vor Brennstoff" [Flame without fuel]
052 No start or safety time overshoot No flame was detected within the ignition phase.
• Check combustion air inlet and exhaust gas piping.
• Check fuel supply (supply and return).
• Check flame pipe to make sure it is correctly mounted in the heat
exchanger.
• Check functioning of the ignition spark generator only with the test unit for
burner head; if necessary, replace the ignition spark generator.
• Check ignition electrode, adjust and, if necessary, replace.
• Check electric leads and connections.
• Check flame monitor for dirt accumulation and, if necessary, clean.
• Replace fuel atomizer nozzle.
• If the fault could not be eliminated by taking the remedial measures listed
above, then replace control unit.
High voltage
Take care when checking the
ignition spark generator!
4 / Troubleshooting