P0121: Throttle or pedal position sensor A circuit range or performance

The throttle position signal does not match what the computer expects. The driver may notice hesitation, unstable idle or limited power.

Likely causes, most common first

  • Worn throttle position sensor
  • Dirty throttle body
  • Wiring or connector fault
  • Faulty throttle body assembly

Parts usually involved

  • Throttle position sensor
  • Throttle body
  • Sensor connector

Test before you replace

Watch the position signal for smooth change while moving the throttle and inspect the throttle body.

General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.

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