P0123 — Throttle Position Sensor/Switch A Circuit High Input
Drive with caution — fix soon.
What P0123 means
This code means the computer is reading an abnormally high voltage signal from throttle position sensor A, the part that reports how far the throttle is open. It's typically caused by a failing throttle position sensor, a wiring short to power, or a bad connection in the circuit. Repairs usually involve fixing wiring or replacing the sensor, and it's a common, fixable issue.
Common symptoms
- Check engine light is on
- Engine surges or revs unexpectedly
- Hesitation or poor acceleration
- Reduced engine power or limp mode
- Rough or unstable idle
Common causes
- Faulty throttle position sensor
- Wiring shorted to voltage or power
- Open or broken signal wire
- Corroded or loose connector
- Failing throttle body assembly
Typical repair cost
$100 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0123 code?
Short trips are usually okay, but it's not ideal. The car may surge or lose power unexpectedly, so avoid highway driving and get it checked promptly to stay safe.
How much does it cost to fix a P0123?
Expect roughly $100 to $400. Repairing wiring or a connector is cheaper, while replacing the throttle position sensor or throttle body raises the cost depending on the vehicle.
Is a P0123 code serious?
It's moderately serious. It rarely leaves you stranded immediately, but unpredictable throttle behavior and possible limp mode mean it should be repaired soon for safe, smooth driving.
What causes a high signal in P0123?
Usually a sensor wire shorted to power, a failing throttle position sensor, or a bad connector that pushes the voltage reading too high. A mechanic can test the circuit to pinpoint which one it is.