How much does it cost to fix P2128?

DIY repair typically costs $50–$200 for parts. Professional repair runs $150–$550 including parts and labor.

P2128

Powertrain

Moderate

Throttle/Pedal Position Sensor/Switch "E" Circuit High

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Code P2128 means the engine computer has detected that the voltage from the 'E' circuit of the throttle or accelerator pedal position sensor is higher than expected. This is essentially the opposite of P2127 — instead of the signal being too low, it's too high. The computer interprets a high voltage as indicating the pedal is being pressed more than it actually is, which creates a potential unintended acceleration risk.

Because of this safety concern, the vehicle will typically enter limp mode immediately. You might notice the engine revving higher than normal at idle, the car surging forward, or the throttle not returning to idle when you release the gas pedal. In some cases the PCM will severely limit engine power as a precaution, making the vehicle barely drivable.

This is a code you should address promptly due to the potential for unintended acceleration. Start by inspecting the wiring harness and connector at the gas pedal for any signs of damage, corrosion, or shorts. If the wiring is clean, the pedal position sensor assembly is the most common replacement. The repair is straightforward — the pedal assembly is accessible in the footwell and typically requires only basic hand tools to replace.

Severity

Moderate — Address SoonThis Week

Symptoms

•Engine enters limp mode with very restricted power
•Unintended acceleration or high idle speed
•Throttle does not return to idle properly
•Check Engine Light illuminated
•Vehicle may surge or lurch unexpectedly

Likely Causes

Faulty accelerator pedal position sensor40%

Internal failure of the E circuit sensor can cause it to output voltage above the maximum expected threshold, making the PCM believe the pedal is being pressed further than it actually is.

Short to voltage in the E circuit wiring25%

A wire shorted to battery voltage or the 5V reference line can artificially raise the E circuit signal, creating an abnormally high reading at the PCM.

Corroded or contaminated connector20%

Moisture or corrosion bridging pins in the pedal sensor connector can create a short between the signal wire and the reference voltage wire, pulling the signal voltage high.

Throttle body sensor fault15%

On some vehicles, the E circuit includes a throttle body position sensor. A failing TPS that reads high can set this code, especially if the sensor's resistance track is worn at specific positions.