What does P0120 mean?
The throttle position sensor (TPS) tells the computer how far the throttle is open. On electronic throttle systems there are two TPS signals that must agree with each other and with the accelerator pedal sensors.
The computer has detected an electrical fault in the sensor circuit.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Reduced power or limp mode
- Hesitation or surging
- Erratic idle
- Shifting problems on automatics
Common causes
- Open or shorted wiring
- Corroded or loose connector
- Failed sensor
- Blown fuse or reference voltage issue shared with other sensors
How to diagnose P0120
- Look for other codes that share the same 5 V reference circuit.
- Inspect the connector and wiring, then check reference, ground and signal voltages.
- Replace the sensor only after the wiring tests good.
- Watch TPS voltage in live data while slowly pressing the pedal (key on, engine off). It should move smoothly with no dropouts.
- Check the throttle body for carbon buildup.
How to fix it
- Clean the throttle body (then do the idle relearn if needed)
- Repair wiring
- Replace the TPS or throttle body
Estimated repair cost
Likely repairs for P0120 run from about $100 to $900, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Throttle position sensor | $100 - $300 |
| Electronic throttle body replacement | $300 - $900 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0120?
High severity
Limp mode can limit speed, so plan to fix it soon. Sudden loss of power in traffic is a safety risk.
P0120 FAQ
What does P0120 mean?
P0120 stands for "Throttle/Pedal Position Sensor/Switch "A" Circuit". The throttle position sensor (TPS) tells the computer how far the throttle is open.
Can I drive with a P0120 code?
Limp mode can limit speed, so plan to fix it soon. Sudden loss of power in traffic is a safety risk.
How much does it cost to fix P0120?
It depends on the cause. The likely repairs for P0120 range from about $100 to $900 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0120?
The most common causes are: open or shorted wiring; corroded or loose connector; failed sensor.