Error code

OBD2 P0123

OBD2P0123
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Throttle/Pedal Position Sensor/Switch 'A' Circuit High.

Severity

moderateCan drive, but performance issues may occur.

Summary

P0123 indicates that the throttle position sensor (TPS) or accelerator pedal position sensor 'A' is providing an abnormally high voltage signal to the engine control module (ECM). This can be due to a wiring issue, faulty sensor, or alternator problems.

Symptoms

  • Hesitation or stumbling upon acceleration
  • Unstable idle
  • Illuminated check engine light

Common Causes

  • Faulty throttle position sensor (TPS)
  • Short circuit in the TPS wiring
  • Defective alternator producing excessive voltage
  • PCM malfunction

Diagnosis

  1. Visually inspect the sensor and its wiring for damage or corrosion.
  2. Check throttle body assembly for binding or contamination.
  3. Test TPS using a multimeter to verify voltage readings at idle and wide open throttle (WOT).
  4. Inspect power supply and ground connections of the TPS circuit.

Fixes

  • Replace faulty throttle position sensor or accelerator pedal position sensor 'A'.

FAQ

What should I do if my car has P0123?

Start by visually inspecting the TPS and its wiring. If no issues are found, proceed to test the sensor's voltage readings using a multimeter.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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