OBD-II Generic Error Code P2123: How to Fix It

Medium 1-2 hours Medium Severity Verified June 2026
Summarize with ChatGPTSummarize with ClaudeSummarize with Perplexity Add as Preferred Source on Google
Error Code
P2123
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
1-2 hours
Error code P2123 indicates that the engine control module (ECM) has detected a high voltage signal from the accelerator pedal position sensor 'D'. This can cause reduced engine power, poor throttle response, or the vehicle entering limp mode. The issue is often related to a faulty sensor, wiring problems, or a malfunctioning throttle pedal assembly.
Ad

Tools You'll Need

How to Fix Error Code P2123

  1. Safety Precautions

    Always disconnect the battery when working on electrical systems and avoid shorting terminals.

  2. Inspect the Accelerator Pedal Assembly and Wiring

  3. Check Sensor Voltage Using Multimeter

    Use back-probing pins carefully to avoid damaging connectors. Do not short pins.

  4. Test Throttle Pedal Position Sensor D Resistance

    Ensure ignition is OFF before disconnecting the sensor.

  5. Inspect ECM Connections and Grounds

    Handle ECM connectors carefully to avoid static discharge damage.

  6. Replace the Accelerator Pedal Position Sensor or Assembly

    After replacement, clear the code using an OBD2 scanner and test drive to confirm repair.

Parts You May Need

Accelerator Pedal Position Sensor or Pedal Assembly
Check Price on Amazon
Accelerator Pedal Position Sensor or Pedal Assembly
Check Price on Amazon
Accelerator Pedal Position Sensor or Pedal Assembly
Check Price on Amazon
Accelerator Pedal Position Sensor or Pedal Assembly
Check Price on Amazon
Ad

When to Call a Professional

If you have cleared the code and it returns, or if you are uncomfortable testing electrical circuits, consult a professional mechanic. Also, if the vehicle exhibits dangerous throttle behavior (unintended acceleration), seek immediate professional help.

Frequently Asked Questions

Can I drive with error code P2123?
It is not recommended. The vehicle may enter limp mode with reduced power, and throttle response may be unpredictable. Driving could be dangerous.
Will cleaning the accelerator pedal sensor fix P2123?
Cleaning is rarely effective because the sensor is sealed. The error is usually due to electronic failure or wiring issues, not dirt. Replacement is typically required.
How much does it cost to fix P2123?
Cost varies by vehicle. A new accelerator pedal assembly ranges from $50 to $200 for parts, plus labor (1-2 hours at shop rates $75-$150/hour). DIY reduces cost to parts only.
What are the symptoms of code P2123?
Common symptoms include check engine light, reduced engine power, poor acceleration, hesitation, and the vehicle entering limp mode.
Can a bad battery cause P2123?
A weak battery can cause erratic sensor readings, but it is unlikely to directly cause P2123. However, low voltage can affect ECM performance, so ensure the battery is fully charged and connections are clean.

Related Error Codes