BMW DTC P31B4 – Cylinder 4 H2-Injector High Side Shorted to Coil
DTC P31B4 meaning on BMW
DTC P31B4 on a BMW indicates that there is a high side short circuit between the hydrogen injector and the coil in cylinder 4. This fault code is specific to the hydrogen fuel injection system in certain BMW models.
BMW DTC P31B4 symptoms
Symptoms of DTC P31B4 on a BMW may include rough idling, misfiring, loss of power, and potentially an illuminated check engine light on the dashboard. The vehicle may also experience decreased fuel efficiency.
BMW DTC P31B4 causes
The most common causes of DTC P31B4 on a BMW are a short circuit between the hydrogen injector and the coil in cylinder 4. This can be due to damaged wiring, a faulty injector or coil, or a problem with the engine control module.
BMW DTC P31B4 seriousness
DTC P31B4 should be addressed promptly to prevent further damage to the engine and ensure the vehicle operates efficiently. Ignoring this fault code can lead to more severe engine issues and potentially unsafe driving conditions.
How to diagnose DTC P31B4 on BMW
To diagnose DTC P31B4 on a BMW, a mechanic will typically use a diagnostic scanner to retrieve the fault code and perform a visual inspection of the hydrogen injector and coil in cylinder 4. They may also test the wiring and connections for any signs of damage.
How to fix DTC P31B4 on BMW
Fixing DTC P31B4 on a BMW may involve repairing or replacing the damaged wiring, hydrogen injector, or coil in cylinder 4. The engine control module may also need to be checked and reprogrammed if necessary. It is recommended to consult a professional mechanic for proper diagnosis and repair.
How to erase DTC P31B4 on BMW
Once the underlying issue causing DTC P31B4 on a BMW has been resolved, the fault code can be erased using a diagnostic scanner. This will clear the code from the engine control module’s memory and turn off the check engine light on the dashboard.
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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