What it means
Torque management feedback signal A is not performing as expected. The code does not identify a particular source module or establish that a shift request was missed.
At a glance
- Usually lights the check-engine light
How it works
Torque management feedback signal A carries information used by engine or transmission controls to coordinate torque requests between modules. The receiving module monitors whether the required network message arrives on time or whether the source module reports an internal fault; either condition can set P2637.
Common causes
Most likely first.
- Required CAN message not received in time
- Source module reports an internal fault
Symptoms
- Check-engine light
- Reduced engine power or altered shifting, depending on the vehicle
How to diagnose it
- Record freeze-frame data and scan all modules for related communication or source-module faults, since P2637 does not identify which module failed to provide feedback signal A.
- Check whether reduced power or altered shifting began at the same time as the code, and note any other network or module warnings.
- Inspect accessible network wiring and connectors for damage, loose pins, corrosion, or poor connections that could interrupt the required message.
- Use a scan tool to confirm whether the relevant feedback message is present and updating, if the vehicle provides that data.
- Diagnose any codes reported by the module that supplies signal A using the vehicle's wiring information and manufacturer procedures.
Common fixes
- Repair a loose, damaged, or corroded network connector.
- Repair damaged network wiring causing intermittent communication.
- Address the source module's reported internal fault after confirming it is the sender of signal A.
- Replace a faulty module only after its power, grounds, wiring, and communication have been checked.
Can I keep driving?
If the engine runs and shifts normally, a short trip to diagnose the fault may be reasonable, but avoid towing, hard acceleration, or relying on predictable shifting. Stop if power drops sharply or shifting becomes unsafe.
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.