P2638
Torque Management Feedback Signal A Range/Performance
The torque feedback signal A is present but its value is implausible against measured engine load and speed. Sender calibration or sensor offset is suspected.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Sender calibration driftPossible
- Bus value corrupted by EMIPossible
- Sensor element aged beyond calibration windowLess likely
Parts involved
- TCM
- Torque Sensor
P2638 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.