P2644Torque Management Feedback Signal B High
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- P2644 reports that torque management feedback B exceeds its upper range limit. No manufacturer publishes a code-specific description. The closest documented case is Allison's P2641: a 2013 Cummins ISX12 calibration reported more torque than the low-range cap allowed, and Mack and Volvo trucks showed the same code under heavy load until the engine software was updated. A reading that is not just above the cap but beyond any valid value points to the same family of problems, namely engine software that scales or encodes the torque message differently from what the transmission expects, or a wired signal shorted to voltage. Low ranges may be locked out and the warning lamp lit. P2643 is the low fault, P2640 the high fault of signal A.
- What you may notice
- Transmission warning lamp on
- Low ranges blocked
- Shift quality reduced
- Likely causes
- LikelyEngine software sends torque with a scaling the transmission does not expect
- PossibleEngine calibration older than the level required by the transmission maker
- RareWired feedback line shorted to voltage
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.