P0120 Throttle/pedal position sensor A circuit
What P0120 means
The engine computer has a problem with the signal from throttle position sensor A, which reports how far the throttle is open (or, on some cars, how far the accelerator pedal is pressed). On electronic throttles the computer usually limits engine power to keep the car safe.
P0120 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 60–500 €
- Workshop time
- 0.5–1.5 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Limp mode with reduced throttle response
- Hesitation, surging or jerky acceleration
- Idle speed too high or too low
Common causes
- Worn sensor track in the electronic throttle body
- Damaged wiring or loose connector to the throttle body or pedal
- Failed accelerator pedal position sensor
- Problem in the 5 V reference circuit from the engine computer
Can I keep driving with P0120?
Get it checked within a day or two. The car will often run in limp mode with very little acceleration, which can be dangerous when joining traffic or overtaking.
What to check first
- Check the throttle body and pedal connectors for corrosion, bent pins and damaged wiring.
- Read the live throttle position signals while slowly opening the throttle; they should change smoothly without dropouts.
- Measure the 5 V reference and ground at the sensor connector.
- Replace the throttle body or pedal assembly (the sensor is usually integrated) and run the throttle adaptation procedure.
Related codes
- P0121 Throttle/pedal position sensor A range/performance
- P0122 Throttle/pedal position sensor A circuit low
- P0123 Throttle/pedal position sensor A circuit high
- P0125 Insufficient coolant temperature for closed-loop fuel control
- P0128 Coolant thermostat: coolant temperature below regulating temperature
- P0118 Engine coolant temperature sensor 1 circuit high
- P0117 Engine coolant temperature sensor 1 circuit low
- P0116 Engine coolant temperature sensor 1 range/performance
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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