BMW DTC P0686 – ECM/PCM Power Relay Control Circuit Low
DTC P0686 meaning on BMW
DTC P0686 on a BMW indicates a problem with the ECM/PCM power relay control circuit. This fault code is triggered when the powertrain control module (PCM) detects that the voltage signal from the relay control circuit is lower than the specified threshold.
BMW DTC P0686 symptoms
Symptoms of DTC P0686 on a BMW may include:
- Engine stalling or not starting
- Loss of power
- Check Engine Light (CEL) illuminated on the dashboard
- Difficulty in accelerating
BMW DTC P0686 causes
The common causes of DTC P0686 on a BMW are:
- Defective ECM/PCM power relay
- Faulty wiring or poor connections in the power relay control circuit
- Low battery voltage
- Corrosion or damage to relay terminals
BMW DTC P0686 seriousness
DTC P0686 should be addressed promptly as it can lead to drivability issues and potential engine damage if left unresolved. Ignoring this fault code may result in the vehicle becoming inoperable.
How to diagnose DTC P0686 on BMW
To diagnose DTC P0686 on a BMW, follow these steps:
- Use a diagnostic scanner to retrieve the fault code and freeze frame data
- Inspect the ECM/PCM power relay and its connections for any visible damage or corrosion
- Check the battery voltage to ensure it is within the specified range
- Perform a continuity test on the power relay control circuit to identify any open or short circuits
How to fix DTC P0686 on BMW
To fix DTC P0686 on a BMW, consider the following steps:
- Replace the ECM/PCM power relay if it is found to be faulty
- Repair any damaged wiring or connectors in the power relay control circuit
- Clean any corrosion from the relay terminals and ensure a secure connection
- Reset the fault code and test drive the vehicle to confirm the issue has been resolved
How to erase DTC P0686 on BMW
To erase DTC P0686 on a BMW, you can:
- Use a diagnostic scanner to clear the fault code from the PCM memory
- Disconnect the vehicle’s battery for a few minutes to reset the PCM
- After clearing the code, perform a final scan to ensure the fault code has been successfully erased