P2139 indicates the engine computer has detected a voltage mismatch between two or more throttle pedal position sensor circuits, typically the primary and secondary/backup signals. The system compares these redundant signals for safety, and when they do not track together within an expected range it sets this correlation fault. It usually points to the pedal position sensor or its wiring rather than the throttle body.
The pedal position sensor assembly contains redundant signal tracks; if one track wears or drifts, the two voltages no longer correlate and trigger the code.
Corroded, loose, chafed, or bent pins in the pedal sensor connector can alter one signal voltage while the other remains normal, causing a correlation error.
A sticking or electrically failing throttle body can indirectly cause pedal/throttle correlation faults because the PCM compares commanded pedal position against actual throttle plate movement.
A weak 5-volt reference or shared ground circuit can skew one of the redundant sensor signals without fully disabling it.
Rarely, an internal ADC or input circuit fault in the PCM can misread one of the pedal position channels; this should only be considered after all sensor and wiring checks pass.
Not exactly. P2139 is primarily about the throttle pedal position sensor signals not matching each other, though a failing throttle body can sometimes contribute to related correlation faults.
It may be unsafe. The vehicle often enters reduced-power or limp mode, and throttle response can be unpredictable. Have it diagnosed before extended driving.
Almost never. The PCM is the least likely cause. Most cases are a worn pedal position sensor or a wiring/connector issue, and replacing the computer without proving the sensor and harness are good usually does not fix it.
On most vehicles the pedal position sensor is plug-and-play and learns its range during the first key cycles, but some makes require a relearn or adaptation procedure with a scan tool.