OBD-II Generic Error Code P0123: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
P0123
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code P0123 means the engine control module (ECM) is detecting an abnormally high voltage from the throttle position sensor (TPS) A. This sensor tells your car's computer how far the gas pedal is pressed. A faulty TPS or wiring issue can cause poor acceleration, stalling, or a check engine light.
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Tools You'll Need

How to Fix Error Code P0123

  1. Safety First – Park and Disconnect Battery

    Always disconnect the battery when working on electrical components. Wait at least 5 minutes for the system to discharge.

  2. Locate the Throttle Position Sensor (TPS)

  3. Inspect Wiring and Connector

    Do not use harsh chemicals that may damage the plastic.

  4. Test TPS Voltage with Multimeter

    Be careful not to short pins. Avoid touching moving parts.

  5. Replace TPS if Faulty

    Do not overtighten screws; they can break or warp the sensor.

  6. Reconnect Battery and Clear Codes

  7. If Code Returns – Check ECM or Throttle Body

    Throttle body cleaner can be flammable. Work in a well-ventilated area.

Parts You May Need

Throttle Position Sensor (TPS)
Check Price on Amazon
Throttle Position Sensor (TPS)
Check Price on Amazon
Throttle Position Sensor (TPS)
Check Price on Amazon
Throttle Position Sensor (TPS)
Check Price on Amazon
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When to Call a Professional

If you are not comfortable working with electrical systems, or if the error code returns after replacing the TPS, a mechanic should diagnose potential ECM or wiring harness issues.

Frequently Asked Questions

Can I drive my car with the P0123 code?
It is not recommended. The TPS issue can cause stalling, reduced power, or unintended acceleration. Have it repaired as soon as possible.
How much does it cost to fix error P0123?
A DIY TPS replacement costs about $30-$80 for the part. Professional repair can cost $100-$250 depending on labor rates.
What other codes are related to P0123?
Related codes include P0120 (TPS circuit malfunction), P0121 (TPS range/performance), P0122 (TPS low input), and P0124 (TPS intermittent).
Can a bad TPS cause transmission problems?
Yes, a faulty TPS can cause erratic shifting or delayed gear changes because the ECM uses TPS data to control transmission behavior.
Will clearing the code fix P0123 permanently?
No, clearing the code only turns off the check engine light temporarily. The underlying issue must be repaired to prevent the code from returning.

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