What it means
A fault is detected in torque management feedback signal B. The code does not identify the source of the signal or the cause of the fault.
At a glance
- Usually lights the check-engine light
How it works
The powertrain control module uses feedback signal B to coordinate requested engine torque with other vehicle systems. P2641 is set when the expected CAN message for signal B does not arrive in time or the source module reports an internal fault.
Common causes
Most likely first.
- Required CAN message not received in time
- Source module reports an internal fault
Symptoms
- Reduced engine power or torque
- Hesitation or sluggish acceleration
How to diagnose it
- Record freeze-frame data and check whether reduced torque or hesitation occurred when the code set.
- Scan all modules for communication and internal fault codes that could identify the source of feedback signal B.
- Check live data and module status to see whether the signal B message is present or missing.
- Inspect the network wiring and connectors between the powertrain module and the module that supplies signal B for damage, corrosion, or loose connections.
- If wiring and message delivery appear sound, follow the vehicle's diagnostic information to test the reporting module and its network connections.
Common fixes
- Repair a loose, damaged, or corroded CAN connector or wire.
- Repair a network fault preventing the signal B message from arriving on time.
- Address the internal fault reported by the source module.
- Replace or reprogram a faulty source module if testing confirms it is the cause.
Can I keep driving?
Drive gently only if the vehicle responds predictably; reduced torque or hesitation can make merging and overtaking unsafe. Avoid demanding acceleration and stop if power loss becomes severe.
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.