BMW DTC P304B – Controlled Upper Air Shutter, Lower Stop Not Detected
DTC P304B meaning on BMW
DTC P304B on a BMW refers to the Controlled Upper Air Shutter, Lower Stop Not Detected fault code. This code indicates that the engine control module (ECM) has detected an issue with the upper air shutter in the intake system not reaching its lower stop position as expected.
BMW DTC P304B symptoms
Symptoms of DTC P304B on a BMW may include rough idling, reduced engine performance, decreased fuel efficiency, and potentially an illuminated check engine light on the dashboard.
BMW DTC P304B causes
The causes of DTC P304B on a BMW can vary, but common reasons include a faulty upper air shutter actuator, wiring issues, or a malfunctioning engine control module.
BMW DTC P304B seriousness
While DTC P304B may not cause immediate drivability issues, it is important to address this fault code promptly to prevent potential long-term damage to the engine or other components.
How to diagnose DTC P304B on BMW
To diagnose DTC P304B on a BMW, a mechanic would typically use a diagnostic scanner to retrieve the fault code and then perform a visual inspection of the upper air shutter and its components. They may also test the upper air shutter actuator and check for any wiring faults.
How to fix DTC P304B on BMW
Fixing DTC P304B on a BMW may involve replacing the faulty upper air shutter actuator, repairing any damaged wiring, or reprogramming the engine control module if necessary. It is recommended to follow the manufacturer’s repair procedures and use genuine BMW parts for the best results.
How to erase DTC P304B on BMW
Once the underlying issue causing DTC P304B on a BMW has been resolved, the fault code can be cleared using a diagnostic scanner. This will reset the check engine light and allow the vehicle’s ECM to monitor the system for any new faults.
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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