B0874 BMW Fault Code
Check B0874 OBD Fault Code ReasonBrake Switch Circuit Input Malfunction Indicates PCM did not receive a brake pedal position (BPP) input. Open or short in BPP circuit Open or short in stoplamp circuits damaged PCM Malfunction in module(s) connected to BPP circuit.
(Rear Electronic Module [REM] Windstar and LS6/LS8 or Lighting Control Module (LCM) Continental and Town Car. Damaged brake switch Misadjusted brake switch Check for proper function of stoplamps.
B0874 Code Symptoms :
While fuel economy was increased, acceleration was seriously compromised, and the loss of engine vacuum led to a dangerous loss of braking assist when the B0874 code system was in four-cylinder mode. In addition to these issues, while the company proposed a hydraulically controlled system that could be switched from within the car, the version they implemented had to be manually changed in the engine compartment using hand tools.
Diagnosis And Repairing B0874
Parts or components should not be replaced with reference to only a B0874 DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.
How to fix B0874 code ?
- Damaged ECM
- Continuous oil flow to the VCT piston chamber
- Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
- Incorrect fuel pressure
A good starting point in your diagnosis is checking all system fuses and fusible links. This can be done using the BMW DVOM on the voltage setting. You will want to test the fuses with circuits loaded.
Some fuses will appear normal until a load is placed on their respective circuit; at which point they will fail. This has been the cause of many 'phantom malfunctions'. Consult your vehicle information source for fuse and fusible link locations. If all fuses are in working order, you may want to check TCM relay operation by swapping identical relays. Usually the horn relay, starter relay, fuel pump relay, air conditioning clutch relay, and controller relays are similar enough in design to swap for diagnostic purposes.
