BMW DTC P304C – Controlled Upper Air Shutter, Upper Stop Not Detected
DTC P304C meaning on BMW
The DTC P304C code for BMW indicates an issue with the Controlled Upper Air Shutter, Upper Stop Not Detected. This means that the vehicle’s engine control module (ECM) has detected a problem with the upper air shutter system, specifically related to the upper stop position not being detected as expected.
BMW DTC P304C symptoms
Symptoms associated with the BMW DTC P304C code may include:
- Check Engine Light (CEL) illuminated on the dashboard
- Reduced engine performance or power
- Engine running rough or misfiring
- Decreased fuel efficiency
BMW DTC P304C causes
The potential causes of the BMW DTC P304C code include:
- Faulty upper air shutter assembly
- Wiring or connector issues in the upper air shutter circuit
- Defective upper air shutter position sensor
- ECM software or hardware problems
BMW DTC P304C seriousness
While the BMW DTC P304C code may not always result in immediate drivability issues, it is important to address the underlying problem promptly. Ignoring this code can lead to potential engine performance issues and decreased fuel efficiency over time.
How to diagnose DTC P304C on BMW
To diagnose the DTC P304C code on a BMW, a mechanic would typically perform the following steps:
- Use a diagnostic scanner to retrieve the fault codes stored in the ECM
- Inspect the upper air shutter assembly for any visible damage or obstructions
- Check the wiring and connectors in the upper air shutter circuit for continuity and proper connections
- Test the upper air shutter position sensor for proper operation
- Verify the upper air shutter stop position using diagnostic tools
How to fix DTC P304C on BMW
To fix the DTC P304C code on a BMW, the following steps may be taken:
- Replace the faulty upper air shutter assembly if necessary
- Repair any damaged wiring or connectors in the upper air shutter circuit
- Replace the defective upper air shutter position sensor
- Update the ECM software if required
How to erase DTC P304C on BMW
To erase the DTC P304C code on a BMW, the fault codes can be cleared using a diagnostic scanner. After addressing the underlying issue causing the code, the ECM can be reset to clear the code and turn off the Check Engine Light.
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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