P1239 – BMW DTC

BMW DTC P1239 – Secondary Upstream Manifold Air Pressure Sensor Signal Too Low at Engine stop

DTC P1239 meaning on BMW

The Diagnostic Trouble Code (DTC) P1239 on a BMW indicates that the Secondary Upstream Manifold Air Pressure Sensor is sending a signal that is too low when the engine is stopped. This sensor is responsible for measuring the pressure in the intake manifold and providing feedback to the engine control module.

BMW DTC P1239 symptoms

Symptoms of DTC P1239 on a BMW may include:

• Check Engine Light illuminated
• Engine stalling or rough idling
• Reduced engine performance
• Potential difficulty starting the engine

BMW DTC P1239 causes

Possible causes of DTC P1239 on a BMW include:

• Faulty Secondary Upstream Manifold Air Pressure Sensor
• Wiring or connector issues in the sensor circuit
• Intake manifold air leaks
• Issues with the engine control module

BMW DTC P1239 seriousness

While DTC P1239 may not always result in immediate drivability issues, it is important to address this code promptly to prevent potential engine performance problems and further damage.

How to diagnose DTC P1239 on BMW

To diagnose DTC P1239 on a BMW, a mechanic may perform the following steps:

1. Use a diagnostic scanner to retrieve the fault code and related data
2. Inspect the Secondary Upstream Manifold Air Pressure Sensor and its wiring for any visible damage
3. Check for intake manifold air leaks
4. Test the sensor’s signal output using a multimeter

How to fix DTC P1239 on BMW

To fix DTC P1239 on a BMW, the following steps may be taken:

1. Replace the faulty Secondary Upstream Manifold Air Pressure Sensor
2. Repair any damaged wiring or connectors in the sensor circuit
3. Address any intake manifold air leaks
4. If necessary, reprogram or replace the engine control module

How to erase DTC P1239 on BMW

To erase DTC P1239 on a BMW, the fault code can be cleared using a diagnostic scanner. After addressing the underlying issue that caused the code, clearing the code will reset the Check Engine Light and allow for monitoring of the system for any recurring problems.

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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