Throttle/Pedal Position Sensor/Switch C Circuit Low

What it means

The engine computer has detected that the C signal voltage in the throttle or accelerator pedal sensor system is below its minimum. The usual cause is an open in the reference or signal wire or a short to ground, and the engine usually enters limp mode.

Related codes: P0225P0228P2127P2138P0651

Symptoms4

• Check engine light on with a reduced power message.
• Very weak acceleration or limited pedal response.
• High or fixed idle speed on some vehicles.
• Codes for other sensors sharing the reference voltage may appear.

Possible causes6

• Unplugged or corroded sensor connector.
• Open in the reference voltage wire or the C signal wire.
• Signal wire shorted to ground.
• A shorted sensor sharing the same reference voltage.
• Internal sensor failure.
• Reference voltage circuit fault inside the engine computer (rare).

How to diagnose5

1. Use the service information to identify which sensor carries the C signal and which reference voltage circuit feeds it.
2. Watch the C signal voltage on a scan tool; a reading near zero means an open or short to ground.
3. Measure the reference voltage at the connector and compare it with the specification.
4. If the reference voltage is low, unplug the sensors sharing it one at a time to find the cause.
5. Check continuity of the signal wire and its isolation from ground.

How to fix5

1. Reseat, clean or replace the connector.
2. Repair the reference or signal wire that is open or touching ground.
3. Replace another sensor proven to be pulling down the reference voltage.
4. Replace the pedal sensor or throttle body assembly depending on where the fault is, then perform the relearn.
5. Clear the codes, then road test and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a connector or wire repair, rises for a pedal sensor, and reaches the upper end when the electronic throttle body assembly is replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions