P0123 serious

Throttle/Pedal Position Sensor A Circuit High Input

What does P0123 mean?

The P0123 code means the vehicle's onboard diagnostic system has detected: Throttle/Pedal Position Sensor A Circuit High Input. This is a serious severity code.

Common Symptoms

  • Check Engine Light on
  • High idle speed
  • Possible uncontrolled acceleration
  • Engine limp mode
  • Throttle sluggish

Probable Causes (Ranked by Likelihood)

  • TPS signal voltage above maximum threshold Very High
  • Short to 5V reference or 12V in signal wire High
  • Failed TPS with stuck-high output High
  • PCM input circuit fault Low

Step-by-Step Diagnostic Procedure

  1. Check TPS signal voltage at idle. Above 4.8V at rest indicates a high signal fault.

  2. Disconnect TPS connector. Voltage should drop to 0V if the signal wire is not shorted.

  3. Inspect wiring for contact with 5V reference or other voltage sources.

  4. Replace TPS if signal voltage does not drop when sensor is disconnected.

Frequently Asked Questions

Is a high TPS reading dangerous?

It can be. A stuck-high TPS signal tells the ECU the throttle is wide open at all times. The ECU may richly fuel the engine or enter limp mode. Have this diagnosed promptly.

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