What are the possible causes of BMW P129B code?
- Faulty absolute pressure sensor
- Absolute pressure sensor harness is open or shorted
- Poor electrical connection in the absolute pressure sensor circuit
How to fix BMW P129B code?
Start by checking the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
What are the possible symptoms of BMW P129B code?
- Check Engine Light on (or Service Engine Soon warning light)
What does BMW P129B code mean?
The absolute pressure in the intake manifold is measured by the manifold pressure sensor. If the engine is not running (engine speed = 0), the measured pressure from the intake manifold pressure sensor located downstream of the throttle body is the same as the measured pressure from the boost pressure sensor in the intake manifold system upstream of the throttle.
Additionally, in the ECU, the ambient pressure is measured. If the measured intake pressure differs from the other two pressure measurements, a fault in the intake pressure measurement is detected. Both differences (manifold pressure to boost pressure and manifold pressure to ambient pressure) must exceed a calibratable threshold based on sensor tolerances.