P2123 indicates the engine control module detects a voltage signal from the throttle or accelerator pedal position sensor circuit D that is higher than the expected range. This triggers a fail-safe mode to prevent unintended acceleration and limits engine performance. The vehicle will remain in this protective state until the electrical fault is diagnosed and repaired.
Internal failure within the sensor unit often causes erratic or high voltage signals on circuit D.
Damaged insulation allowing the signal wire to contact a voltage source will trigger a high input code.
Corrosion or loose pins at the sensor connector can disrupt signal integrity and cause high readings.
Spills or debris inside the pedal assembly may interfere with the sensor track resistance.
Issues with the 5-volt reference circuit from the control module can skew sensor readings.
Internal control module failure is possible but statistically rare compared to sensor or wiring faults.
Not necessarily; P2123 often refers to the accelerator pedal sensor, not the throttle body itself.
It is unsafe; the vehicle may enter limp mode or stall unexpectedly, limiting control.
No, PCM failure is extremely rare for this code; focus on the sensor and wiring first.
No, the underlying electrical fault must be repaired to prevent the code from returning.