P0123
Throttle/Pedal Position Sensor A Circuit High Input
The engine computer is getting a voltage signal from the throttle or accelerator pedal sensor that is higher than expected. This usually means the sensor, wiring, or connector has a problem. It can cause poor throttle response, rough running, or reduced engine power.
- SEV
- 3/5
- DRIVE
- CAUTION
- DIY
- $20–$150
- SHOP
- $120–$450
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Faulty throttle position sensor or accelerator pedal position sensor
- Damaged, loose, or corroded wiring/connectors in the sensor circuit
- Short to voltage in the signal wire or harness
Typical repair cost
DIY usually runs $20–$150. Typical shop repair lands around $120–$450, depending on the root cause.
01 / Definition
P0123 means the PCM has detected a high input condition on throttle position sensor or accelerator pedal position sensor circuit A. This usually indicates the signal voltage is above the expected range, often because of a faulty sensor, damaged wiring, poor connector contact, or a short to voltage. The vehicle may enter limp mode to protect the engine and transmission.
02 / Drive status
With caution. You may be able to drive short distances, but throttle response can be unpredictable and the engine may go into reduced-power mode. Avoid highway driving and get the problem checked soon.
03 / Symptoms
- Check engine light on
- Poor throttle response
- Hesitation or surging
- Reduced engine power or limp mode
- High idle or unstable idle
- Harsh shifting on vehicles with electronic throttle control
- Stalling or stumbling in some cases
04 / Causes
| 1 | Faulty throttle position sensor or accelerator pedal position sensor | high |
|---|---|---|
| 2 | Damaged, loose, or corroded wiring/connectors in the sensor circuit | high |
| 3 | Short to voltage in the signal wire or harness | medium |
| 4 | Throttle body contamination or mechanical binding affecting sensor reading | medium |
| 5 | Low-quality aftermarket sensor or incorrect replacement part | medium |
| 6 | PCM/ECM issue or damaged reference voltage circuit | low |
05 / Diagnostic sequence
- 01Scan for related codes and freeze frame data, especially throttle, pedal, reference voltage, and correlation codes.
- 02Inspect the throttle body, accelerator pedal sensor, wiring harness, and connectors for damage, corrosion, moisture, or loose pins.
- 03Check the live data for throttle/pedal position readings with key on and engine off. Look for a reading stuck high or jumping unexpectedly.
- 04Measure the sensor reference voltage, ground, and signal voltage with a multimeter according to the service manual.
- 05Perform a wiggle test on the harness and connector while watching live data for spikes or drops.
- 06If the wiring checks out, test the sensor itself and verify throttle body operation if equipped with electronic throttle control.
- 07Clear the code and road test after repair to confirm the problem is fixed.
06 / Repairs
| 1 | Clean and reseat the throttle body or accelerator pedal sensor connector; repair minor corrosion or loose pins. | $0–$50 |
|---|---|---|
| 2 | Repair damaged wiring, shorts, or connector terminals in the sensor circuit. | $50–$200 |
| 3 | Replace the throttle position sensor, accelerator pedal position sensor, or electronic throttle body assembly as needed. | $60–$300 |
| 4 | Perform throttle relearn or pedal position relearn if required by the vehicle. | $0–$100 |
| 5 | Diagnose and repair PCM/ECM or reference voltage faults if all other components test good. | $150–$600 |
07 / Related codes
08 / FAQ
Can a bad throttle position sensor cause P0123?
Yes. A failed throttle position sensor or pedal position sensor is one of the most common causes of P0123.
Will P0123 put the car in limp mode?
It can. Many vehicles reduce engine power when the throttle signal is too high or unreliable.
Can I just clear P0123 and keep driving?
You can clear it, but if the fault is still present the code will return. Driving with this code can leave you with poor throttle response or reduced power.
Does P0123 mean I need a new throttle body?
Not always. Wiring, connectors, and the pedal sensor should be checked before replacing the throttle body.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.