P0685 – BMW DTC

BMW DTC P0685 – ECM/PCM Power Relay Control Circuit/Open

DTC P0685 meaning on BMW

The Diagnostic Trouble Code (DTC) P0685 for BMW refers to the ECM/PCM Power Relay Control Circuit/Open. This code indicates that there is an open circuit or a fault in the power relay control circuit of the Engine Control Module (ECM) or Powertrain Control Module (PCM).

BMW DTC P0685 symptoms

Symptoms of DTC P0685 on a BMW may include:

• Engine stalling or not starting
• Loss of power
• Check Engine Light (CEL) illuminated on the dashboard
• Difficulty in starting the vehicle

BMW DTC P0685 causes

The common causes of DTC P0685 on a BMW include:

• Defective ECM/PCM power relay
• Open or short circuit in the power relay control circuit
• Corrosion or poor connection in the wiring related to the power relay

BMW DTC P0685 seriousness

DTC P0685 can be a serious issue as it can lead to engine performance problems and potential stalling of the vehicle. Ignoring this code may result in further damage to the vehicle’s ECM/PCM or other components.

How to diagnose DTC P0685 on BMW

To diagnose DTC P0685 on a BMW, you can follow these steps:

1. Use a diagnostic scanner to retrieve the fault codes stored in the ECM/PCM.
2. Inspect the power relay and its control circuit for any visible damage or corrosion.
3. Check the wiring harness and connectors for any signs of wear or poor connections.
4. Perform continuity and resistance tests on the power relay and circuit to identify any open circuits.

How to fix DTC P0685 on BMW

To fix DTC P0685 on a BMW, you can try the following solutions:

1. Replace the faulty ECM/PCM power relay with a new one.
2. Repair any open or short circuits in the power relay control circuit.
3. Clean or replace any corroded connectors or wiring related to the power relay.
4. Clear the fault codes using a diagnostic scanner after the repairs are completed.

How to erase DTC P0685 on BMW

To erase DTC P0685 on a BMW, you can use a diagnostic scanner to clear the fault codes stored in the ECM/PCM memory. After fixing the underlying issue causing the code, you can reset the system by erasing the code and performing a test drive to ensure the problem has been resolved.

Recommended tools & DTC Scanners for BMW

Best Diagnostic App for modern BMWs: BimmerLink

Recommended Bluetooth adapter for Bimmerlink: OBDLink CX

Cable adapter for Bimmerlink: Enet Cable USB Type C

For older BMWs we recommend: Autel AutoLink AL319 (2024 version)

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

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