P25D6
Exhaust Heat Exchanger Exhaust Bypass Valve A Position Sensor Stop Performance
During self-calibration of the exhaust heat exchanger bypass valve A, the position sensor never reached the expected mechanical stop. The controller cannot zero the position reference, so commanded openings will be inaccurate.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Soot or carbon deposits prevent valve from reaching the stopCommon
- Worn linkage between actuator and valve flapPossible
- Position sensor not aligned with valve shaftPossible
Parts involved
- Exhaust Heat Exchanger
- Bypass Valve Actuator
- Position Sensor
P25D6 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.