P0684 – BMW DTC

BMW DTC P0684 – Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance

DTC P0684 meaning on BMW

DTC P0684 on a BMW indicates a communication error between the Glow Plug Control Module 1 and the Powertrain Control Module (PCM). This code is triggered when the communication circuit’s performance falls outside the expected range.

BMW DTC P0684 symptoms

Symptoms of DTC P0684 on a BMW may include:

• Check Engine Light (CEL) illuminated
• Engine misfires
• Reduced engine performance
• Difficulty starting the engine

BMW DTC P0684 causes

Common causes of DTC P0684 on a BMW include:

• Faulty Glow Plug Control Module 1
• Wiring or connection issues in the communication circuit
• PCM software or hardware problems

BMW DTC P0684 seriousness

DTC P0684 should not be ignored as it can lead to engine performance issues and potential starting problems. It is recommended to address this code promptly to prevent further complications.

How to diagnose DTC P0684 on BMW

To diagnose DTC P0684 on a BMW, you can follow these steps:

1. Use a diagnostic scanner to retrieve the fault codes.
2. Inspect the wiring and connections related to the Glow Plug Control Module 1 and PCM.
3. Check the Glow Plug Control Module 1 for any signs of damage or malfunction.
4. Perform a communication test between the modules to identify any issues.

How to fix DTC P0684 on BMW

To fix DTC P0684 on a BMW, you can try the following:

1. Repair or replace any damaged wiring or connectors in the communication circuit.
2. Replace the Glow Plug Control Module 1 if it is found to be faulty.
3. Update the PCM software if necessary.

How to erase DTC P0684 on BMW

To erase DTC P0684 on a BMW, you can clear the fault codes using a diagnostic scanner. After addressing the underlying issue and making the necessary repairs, you can reset the codes to see if 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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