P2120: Throttle/Pedal Position Sensor/Switch D Circuit — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
Throttle/Pedal Position Sensor/Switch D Circuit. Basic catalogue definition; diagnostic details have not yet been reviewed.
Affected system: Powertrain
Symptoms
- A check-engine warning may appear, with uneven response to accelerator input.
- Some vehicles may hesitate, idle poorly or limit engine power.
Possible causes
- Damaged wiring, loose pins or corrosion in throttle/pedal position circuit D.
- An intermittent position-sensor signal; a sticking throttle mechanism warrants a separate check.
What to check
- Read P2120 together with any related pedal or throttle codes.
- Inspect the pedal/throttle connectors, wire routing and connector pins.
- Track sensor-D live data as the accelerator moves, after locating the circuit in the vehicle diagram.
- Test reference supply, ground and signal wiring to the vehicle specifications before replacing parts.
Also written as: P2120-00, P212000 (some scan tools add the fault-type byte, e.g. -00).