Torque Management Feedback Signal B Low
The P2642 code means the vehicle's onboard diagnostic system has detected: Torque Management Feedback Signal B Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $100 - $800 (parts and labor)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Common Symptoms
- Torque signal B reads lower than expected
- Possible stability system issues
- Transmission shift quality degraded
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Ground fault in torque B signal path Very High
- ECM B output driver degraded High
- CAN bus termination issue Moderate
- TCM B input pulled low Low
Step-by-Step Diagnostic Procedure
-
Compare torque B signal to torque A signal values
-
Check CAN bus termination resistors
-
Test ECM B output circuit
-
Inspect wiring for ground faults
Frequently Asked Questions
What is CAN bus termination?
CAN bus requires termination resistors (typically 120 ohms) at each end of the network. Missing or incorrect termination can cause signal integrity issues.
Can P2642 exist without P2639?
Yes. Signal A and B may use different circuit paths. A fault in the B path does not necessarily affect the A signal.
How do I check CAN bus termination?
With the ignition off, measure resistance between CAN high and CAN low at the diagnostic port. You should read approximately 60 ohms with two 120-ohm terminations in parallel.
Sources
This page is built from documented references. Verify against your own service info before repair work.
Explore More
Was this helpful?
Share carcodefinder.com with a friend who needs to decode their check engine light.