P2642 means the powertrain control module (PCM) has detected that torque-management feedback signal B is outside its expected range or is behaving inconsistently. This feedback tells the PCM whether an requested engine-torque reduction—typically from cruise control, traction control, or a drive-by-wire throttle system—actually occurred. A range/performance fault usually points to the feedback circuit or the component producing the signal, not the PCM itself.
Open, short-to-power, short-to-ground, corroded pins, or poor pin fit in the harness between the PCM and the module or actuator that produces the feedback signal are the most common causes of a range/performance code.
The throttle actuator control module, cruise-control module, or other torque-management actuator can fail internally and send an out-of-range feedback signal to the PCM.
A weak battery, failing alternator, or corroded ground can cause signal voltage to drift or become noisy, leading the PCM to set P2642 even when the actuator is fine.
Outdated PCM or related-module software can misinterpret a valid feedback signal; manufacturers occasionally release updates to correct false or overly sensitive P2642 setting.
PCM failure is possible but uncommon for this code; it should be considered only after wiring, the source module/actuator, and software have been ruled out.
Short trips are usually safe, but the engine may enter reduced-power mode and features such as cruise or traction control may be disabled. It should be diagnosed promptly to avoid unexpected power loss.
Usually not. P2642 refers to the torque-management feedback signal, not the throttle-position sensor. However, problems in related drive-by-wire systems can produce similar symptoms.
Generally no. PCM failure is a rare cause of P2642; most cases are due to wiring, connectors, the module or actuator producing the feedback signal, or low system voltage. Replace the PCM only after proper circuit and component testing rules everything else out.
Yes. Low battery voltage or poor grounds can make feedback signals erratic and trigger this code, so the battery, charging system, and ground connections should be checked.