P2639
Torque Management Feedback Signal A Low
Powertrain torque management
Generic OBD-II
Medium
What it means
P2639 means the torque-management feedback signal 'A' — used to coordinate engine torque with the transmission — read lower than expected. To protect the drivetrain, the vehicle may reduce power or shift the transmission into a limited mode. It's typically a wiring, connector, or ground problem in the feedback circuit, and occasionally a control-module fault.
Medium
Can I keep driving? Yes but reduced — the engine may cut power or the transmission may shift oddly or drop into limp mode; drive gently and repair soon.
Common symptoms
What you'll notice
- Reduced engine power or torque
- Harsh, delayed, or erratic shifts
- Transmission limp mode (fixed gear)
- Check-engine light on
Common causes
Most likely first
- Open, shorted, or low-voltage torque-feedback signal wiringLikely
- Poor connection or ground between the engine and transmission controllersCommon
- Corroded or loose module connectorCommon
- Faulty transmission or engine control moduleLess often
- Related low fluid or mechanical issue skewing torque feedbackLess often
How to diagnose & fix
Work through it in order
- Scan for companion codes that point to the failing side (engine vs. transmission).
- Inspect the torque-feedback signal wiring and grounds for opens, shorts, or corrosion.
- Check the module connectors for backed-out or loose pins.
- Back-probe and test the feedback signal voltage against spec.
- Repair wiring first; consider a control-module fault only after the circuit checks out.
FAQ
Quick answers
Is it safe to drive with P2639?+
Short-term, cautiously. The powertrain may reduce power or limp to protect itself. Drive gently and get it diagnosed before longer trips.
Can I just clear P2639?+
You can, but a wiring or module fault will set it again and the power-reduction behavior returns. Fix the circuit to clear it for good.
Related codes
Often seen with P2639
Read & clear P2639 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX