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C12F8 BMW Fault Code

Check C12F8 OBD Fault Code Reason
Description:

Brake 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.

C12F8 Code Symptoms :

See C12F8 in engine

There are currently two main types of cylinder deactivation used today, depending on the type of engine. C12F8 code for the pushrod design which uses solenoids to alter the oil pressure delivered to the lifters. In their collapsed state, the lifters are unable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be actuated and remain closed.

Diagnosis And Repairing C12F8

C12F8 OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix C12F8 code ?

See C12F8 repair manual
  • Damaged ECM
  • Faulty Mass Air Flow (MAF) sensor
  • Fuel filler cap remains open or fails to close
  • Radio frequency interference (RFI)

To check for an open circuit, trace along the length of the transmission control circuit, checking for breaks in the wiring. Repair any broken wiring and make sure all connectors are fully seated and locked.

Pay close attention to connectors, looking for corrosion, bent or broken pins, or moisture in the connector. Repair any connector issues even if they are not specifically part of the transmission control circuit as they may serve a function in providing power to the transmission control circuit.

BMW Cars that meet C12F8 error