P2642Torque Management Feedback Signal B Range/Performance
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- P2642 means feedback signal B arrives and lies inside its valid range, yet its value makes no sense for the current operating state, for example a torque figure that drifts away from what a limited request should produce or that changes implausibly fast. No manufacturer explains P2642 publicly. Allison ties request B to its low-range torque cap (LRTP) and logs the general code P2641 when the engine exceeds the cap; Honda documents the matching plausibility check for request A as P2638 on its nine-speed automatic and fixed false triggers with software and an idle relearn. By analogy, look first at engine and transmission software levels, then at the idle learn and at sensors feeding the torque model. Shifts may feel rough and low ranges can be restricted.
- What you may notice
- Rough or delayed shifts
- Transmission warning lamp on
- Low ranges restricted
- Likely causes
- LikelyEngine and transmission software versions do not match
- PossibleIdle or torque adaptation not learned after service
- RareFaulty input to the engine torque model (air mass, intake air temperature)
- 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.