P2122 Throttle/pedal position sensor: signal or voltage too low ("D")

By: Diagno editorial team · Updated: 2026-10-15

P2122 means: Throttle/pedal position sensor: signal or voltage too low ("D"). There are usually two throttle or accelerator pedal position sensors and they must agree. Drive gently and have the car checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model.

What it means

There are usually two throttle or accelerator pedal position sensors and they must agree. The computer found a wrong signal or the two don't match. The signal voltage is too low. Usually a wire is broken, a connector is loose or a wire is shorted to ground.

What you may notice

• Engine light on
• Limp mode with no power
• Throttle response is delayed
• Idle hunts

What could be wrong

1. 1Connector loose, damp or corroded · Wiring or connector repair €45–90
2. 2Wire broken or shorted to ground · Wiring or connector repair €45–90
3. 3Faulty sensor or throttle body · Throttle body clean or replace €90–180
4. 4Engine computer fault (rare) · Control unit check and software €150–300

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Check the throttle body and pedal connectors. Cleaning the throttle body often helps. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the sensor or throttle body

Standard SAE description: Throttle/Pedal Position Sensor/Switch "D" Circuit Low