Engine sensors
P0123 — Throttle/Pedal Position Sensor/Switch A Circuit High
The throttle or pedal position sensor A signal is higher than the normal range. The ECU may think the throttle is wide open and react wrongly.
Common causes
- Faulty throttle position sensor
- Signal wire shorted to voltage
- Open ground in the sensor circuit
- Damaged connector
- Faulty throttle body
Symptoms
- Fast or unstable idle
- Surging
- Limp mode
- Check engine light
How to check
- Inspect the connector and harness for a short to voltage
- Check the ground and 5 V reference
- Compare the sensor signal at closed throttle (it should be low)
- Replace the sensor or throttle body if the signal stays high
Can you keep driving?
Not recommended: the car may idle high or lose power unexpectedly. Repair it before normal driving.
Related codes
Frequently asked questions
- What does P0123 mean?
- The sensor A voltage is above its normal range.
- Can an open ground cause P0123?
- Yes. A lost ground raises the signal voltage and can trigger this code.
General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.