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Accelerator Pedal Position Sensor: Understanding the Overview, Symptoms, Diagnosis, and Costs

Published on December 26th, 2023

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The Accelerator Pedal Position (APP) sensor is a critical component for the proper operation of a modern motor vehicle. The APP the movement of the accelerator pedal into electrical signals that help control engine operation.

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Accelerator Pedal Position (APP) sensor

Overview of the Accelerator Pedal Position Sensor

Modern vehicles no longer use mechanical cables between the accelerator pedal and throttle body. Instead, they now employ electronic systems to monitor accelerator pedal position. The APP sensor is typically located near the accelerator pedal. There are various types of sensors, including potentiometers and Hall effect sensors. Regardless of the sensor type, its function is consistent: it provides the Engine Control Module (ECM) with precise information about the driver's throttle input. This information is essential for the ECM to determine how much air and fuel to deliver to the engine, ensuring the vehicle accelerates smoothly and efficiently.

Symptoms of a Faulty APP Sensor

1. Rough Idling: A faulty APP sensor may result in inconsistent idling, impacting fuel delivery and engine stability.

2. Limited Acceleration: If a vehicle has difficulty achieving higher speeds, it indicates the APP sensor isn't sending accurate throttle signals, resulting in poor engine performance.

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Limited Acceleration

3. Inefficient Engine: A faulty APP sensor affects fuel efficiency by failing to maintain consistent throttle control and proper fuel pressure.

4. Inconsistent Acceleration: With a faulty APP sensor, a vehicle may respond sluggishly when the accelerator pedal is operated, compromising driver control and safety.

5. Transmission Issues: A faulty APP sensor can affect automatic transmission shifting, causing jerky movements and delayed signals to the transmission control module.

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Transmission Issues

6. Malfunction Indicator Light (MIL): When the APP sensor malfunctions, it triggers the Malfunction Indicator Lamp (MIL), often indicating a P2135 Diagnostic Trouble Code (DTC). This issue should be diagnosed and corrected by a certified mechanic.

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Malfunction Indicator Light (MIL) ON

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Diagnostic Tips

If a faulty APP sensor suspected, use the following procedure to confirm the issue:

  • Use a diagnostic tool called an OBD2 Scan Tool to check for DTCs related to the sensor.
  • Inspect the wires and connectors connected to the sensor to ensure they are not loose or damaged.
  • Use a multimeter or an oscilloscope to test the sensor's electrical signals.
  • Refer to the vehicle’sService Manual for instructions on how to diagnose and correct the problem.
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Use INNOVA Scan Tool to check DTC

Cost of APP sensor Replacement

Removal and replacement of the APP sensor is best left to a professional mechanic.

The cost of replacing an APP sensor can cost from $100 to $300, including parts and labor. However, cost may vary depending on the vehicle's make and model, the sensor's location, and the labor charges.


The APP sensor is a small, simple component,, but it's function is critical to a vehicle’s performance. Ignoring problems with the sensor can affect driving speed, and result in road safety issues. If signs of a faulty APP sensor are present, have the vehicle inspected and serviced by a professional mechanic. Proper maintenance of the APP sensor will ensure smooth engine operation and ensure a safer, more enjoyable driving experience.

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