What it means
The control module monitors torque management feedback signal B and sets this code when the reported value exceeds its expected range.
At a glance
- Usually lights the check-engine light
How it works
The powertrain control module monitors torque management feedback signal B received over the vehicle network. P2644 is set when the reported value rises above its expected range, such as when the source module sends an invalid high value or the bus signal is stuck high.
Common causes
Most likely first.
- Source module sends invalid high value
- Signal stuck high on the bus
Symptoms
- Reduced engine power or torque
- Hesitation or sluggish acceleration
How to diagnose it
- Save freeze-frame data and note whether the high reading occurred during acceleration, deceleration, or a particular operating condition.
- Check live data for signal B and compare it with related torque request and source-module values.
- Scan all modules for faults that point to an invalid high report or a network communication issue.
- Inspect CAN wiring and connectors for a short to voltage, damaged insulation, corrosion, or poor contact.
- Use the manufacturer's network and module tests to determine whether the signal is being driven high by wiring or by the source module.
Common fixes
- Repair loose, corroded, or damaged CAN connectors.
- Repair a network wire shorted to voltage or otherwise holding the message high.
- Correct a source module fault that produces an invalid high value.
- Replace or reprogram the source module only if testing confirms its output is faulty.
Can I keep driving?
Drive only if power delivery remains predictable; torque reduction or hesitation may make passing and merging unsafe. Avoid hard acceleration and seek prompt diagnosis.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.