What are the possible causes of the BMW P12B9 code?
- Faulty ambient pressure sensor
- Ambient pressure sensor harness is open or shorted
- Poor electrical connection in the ambient pressure sensor circuit
| How to fix the BMW P12B9 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 the BMW P12B9 code?
- Check Engine Light on (or Service Engine Soon warning light)
| What does the BMW P12B9 code mean?
During the control module shutdown phase, the diagnostic function monitors the barometric pressure sensor, intake manifold pressure sensor, and boost pressure sensor to determine if they all measure the same pressure. The ECM sets the OBDII code when the ambient pressure sensor does not meet factory specifications.