P0123 – Throttle/Pedal Position Sensor/Switch A Circuit High Input

Meaning:

The P0123 code is triggered when the voltage the TPS has recorded is too high
When the PCM reports that the TPS has recorded a voltage that is too high, P0123 happens

The PCM is reporting that the TPS has recorded a voltage that is higher than the normal maximum limit, usually around 5 volts.

Main Symptoms:

Possible Causes:

  • Defective TPS
  • Open or short in TPS circuit
  • Improper mounting of TPS after replacement
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Visually inspect all wiring to TPS for loose, open or short connections
  • Check that TPS is tightly in position, especially if you recently replaced it

Read More: Signs Of A Bad Starter