P2644: Torque Management Feedback Signal B Circuit High
What to do
A smooth engine and a gearbox that bangs into gear is the picture, and it is very often a signalling fault rather than a transmission fault — see P2640. No gearbox work should be authorised on the strength of this code. Comparing what the engine module and the transmission module each believe the engine torque to be, on a scan tool, shows the disagreement immediately.
What this code means
The second torque feedback circuit reads above its valid range — an open circuit, a disconnected connector, or a short to supply. The mechanism is at P2637.
As at P2640, a short to supply reports maximum torque continuously, and a transmission applying clutch pressure for a torque far larger than the engine is making produces hard, jolting changes that get read as a failing gearbox. Nothing is being harmed and the complaint points at the wrong component, which is the practical reason to recognise it.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Wiring shorted to voltage · moderate
- Corroded or loose connector · easy
Less common
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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