OBD-II Error Code P0123 - Throttle Position Sensor A Circuit High Input

OBD-II Standard OBD-II Major Fuel and Air Metering

Model: SAE J2012 Standard | Code: P0123

Applicable Systems
OBD-II

Symptoms

Check engine light is on. The engine may run rich, have high idle, or exhibit reduced power. The TPS signal voltage exceeds the maximum acceptable threshold.

Possible Causes

  • TPS signal wire shorted to 5V reference
  • Faulty TPS with high output voltage
  • Corroded TPS connector causing high resistance
  • TPS 5V reference wire shorted to signal wire
  • Aftermarket TPS with incorrect calibration

Troubleshooting Steps

  1. Step 1: Connect an OBD-II scan tool and read all stored DTCs and freeze frame data
    All DTCs and freeze frame data are retrieved
  2. Step 2: Inspect the related sensor or actuator wiring for damage, corrosion, or loose connections
    Wiring and connectors are in good condition
  3. Step 3: Use a digital multimeter to check sensor voltage, resistance, and reference signals per manufacturer specifications
    Values are within specified range
  4. Step 4: Perform component-level testing of the suspected sensor or actuator
    Component passes or fails definitively
  5. Step 5: Clear codes and road test to verify repair
    Code does not return and system operates normally

How to Reset

To reset code P0123: 1) Repair the underlying fault. 2) Use an OBD-II scan tool to clear the DTC. 3) Perform a drive cycle to verify the monitor completes. 4) If the code returns, further diagnosis is needed. Caution: Do not clear codes without fixing the root cause.

Frequently Asked Questions

  • Q: What does OBD-II code P0123 mean?

    Code P0123 indicates: Throttle Position Sensor A Circuit High Input. This is a SAE J2012 standard diagnostic trouble code related to Fuel and Air Metering.

  • Q: Is code P0123 serious?

    Severity: Major. Immediate attention is recommended to prevent further damage.

  • Q: Can I drive with code P0123?

    It is not recommended to drive with this code active as it may cause further damage or safety issues.

  • Q: How do I fix code P0123?

    Diagnose the Fuel and Air Metering system, check wiring and connectors, test the related sensor or actuator, and replace faulty components as needed.

Related OBD-II Standard Fault Codes

Source: SAE J2012 Standard - Powertrain Diagnostic Trouble Codes

Category: OBD-II