Checking components and wiring
Check the cable between combustion preheater module (CPM) terminal #4 and the ground terminal for the flame sensor. Check for an open-circuit.
HINT: It is difficult to differentiate between the flame sensor cables so take readings between control module terminal #4 and both flame sensor cables.
Check the cable between combustion preheater module (CPM) terminal #8 and the positive cable for the flame sensor. Check for an open-circuit. Check for a short-circuit to supply voltage.
HINT: It is difficult to differentiate between the cables to the flame sensor. Take readings on the cables one at a time and see if a relevant value was obtained from either of them.
If no fault is found in the connectors or cables, try a new flame sensor.
Remedy as necessary.
Other information:
- See Connecting the breakout box
- For cars manufactured up to w38 2001 inclusive, see Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing
- For cars manufactured from w39 2001 inclusive, see Replacing the overheat protection thermostat, the flame sensor and the engine coolant temperature sensor .
- For other values: Signal specification
- See Contents
- Continue
Refer to Verification