Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Accelerator pedal (AP) position sensor
The function of the accelerator pedal (AP) position sensor is to provide the engine control module (ECM) and central electronic module (CEM) with information about the position of the accelerator pedal. This data is used by the engine control module (ECM) to deploy the shutter in the throttle unit to the correct angle.
The accelerator pedal (AP) position sensor consists of a plastic housing with two potentiometers, and an Analog/Digital converter. The potentiometers are connected to a common shaft which is affected by the position of the accelerator pedal (AP).
The accelerator pedal (AP) position sensor transmits an analog and a pulse width modulated (PWM signal to the engine control module (ECM). These signals indicate the position of the accelerator pedal (AP). The digital signal is generated by the sensors Analog/Digital converter.
The analog and digital signals are used at the same time by the engine control module (ECM) to regulate the throttle shutter angle.
The power supply to the two potentiometers is different. The analog potentiometer is supplied with 5 V via the engine control module (ECM). The digital potentiometer is supplied with 12 V via the system relay and is grounded in the car body.
The digital signal is also used in conjunction with the analog signal for accelerator pedal (AP) position sensor diagnostics.
Signals from the accelerator pedal position sensor can be read out using VIDA.
A diagnostic trouble code (DTC) is stored if the engine control module (ECM) detects a difference between the analog and digital signals. The engine control module (ECM) then uses a minimal value to ensure the function (limp home).
The accelerator pedal (AP) position sensor is located on the accelerator pedal bracket.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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