Accelerator Pedal Position Sensor

• The accelerator pedal position sensor regulates the fuel that goes to the engine based on how hard you step on the pedal. It tracks the position of the accelerator pedal and sends it to the engine control unit. In comparison, the nearby throttle position sensor checks the position of the throttle valve.
• Symptoms of a bad accelerator pedal position sensor include illuminated Check Engine Light, faster engine idling speed, no response to stepping on the accelerator pedal, and the vehicle entering safe mode.
• Common accelerator pedal position sensor problems include damaged or loose cables and connectors, insufficient voltage and ground supply, and faulty electronic evaluation unit.
• On CarParts.com, an accelerator pedal position sensor can go for anywhere between $3 and $724. You can buy the component on its own or as an assembly.
• When selecting a replacement accelerator pedal position sensor, consider its compatibility with your car and its warranty. Buy a complete assembly whenever you can afford it

The accelerator pedal position sensor regulates the fuel that goes to the engine based on how hard you step on the pedal. Thanks to the accurate positional data from this electronic device, your car’s engine control unit (ECU) releases the correct amount of fuel into the combustion chamber.

A bad or failing accelerator pedal position sensor can lead to engine jerking, stalling, and uncontrolled acceleration. You, therefore, want the best replacement part for it.

This guide will discuss the basics of the acceleration pedal position sensor, including how it runs and the symptoms if it ever goes bad. It will also help you distinguish this sensor from the throttle position sensor.

This sensor is part of the electronic throttle control system with intelligence (ETCSi). Found on the throttle body, it tracks the position of the accelerator pedal and sends the data back to the engine control unit.

When you want to speed up your car, you step on the accelerator pedal. The sensor checks the pedal’s new position, converts it into an electronic signal, and transmits it to the engine computer. Upon getting the signal, the computer opens the throttle body to increase the flow of fuel to the engine.

Once the need for increased engine load diminishes, you lighten the pressure applied by your foot on the pedal. As the accelerator pedal moves back, the sensor updates the engine computer on the pedal’s new position. The computer closes the throttle body, reducing the fuel flow.

The accelerator pedal position sensor sits on the floorboard. Its position puts it right next to the car’s firewall. The heat produced by a running engine can eventually affect or damage the sensor.

The accelerator pedal position sensor shares its throttle body home with a similar device. Called the throttle position sensor (TPS), it checks the position of the throttle valve and the rate at which the valve opens.

Both sensors contain the same number of components and contribute to the engine’s performance. However, they cover distinct parts.

Stepping on the accelerator pedal opens the butterfly valve that covers the throttle. The throttle position sensor measures the angle of the open valve and sends the information back to the powertrain control module.

While the accelerator pedal position sensor regulates fuel flow to the engine, the throttle position sensor controls airflow. The engine control unit uses data sent by the TPS to check if the throttle valve is open or closed. It adjusts the amount of air going to the engine to achieve the most efficient fuel-to-air mixture.

Some symptoms of a bad or failing accelerator pedal position sensor are:

• The Check Engine Light on the dashboard lights up.
• The engine idles at a faster speed than normal.
• Stepping on the accelerator pedal doesn’t produce a response from the engine.
• The vehicle enters a safe mode to ensure it can make it back home.

The accelerator pedal position sensor can come to grief in several ways. The likeliest reasons for its failure include:

• The sensor’s cables or connectors got damaged or loosened, affecting its connection to the engine computer.
• Insufficient voltage and ground supply to run properly, leading to reduced performance.
• Its electronic evaluation unit developed an issue and sent the wrong data to the engine computer.

When you encounter any of the symptoms of a faulty accelerator pedal position sensor, bring your affected car to the nearest, trustworthy auto repair shop. Drivers with plenty of experience in DIY car repair can try to troubleshoot their vehicles. 

Anytime the Check Engine Light activates, plug the OBD-II scanner into the connector port. Check the diagnostic trouble code logged by the engine’s computer module.

OBD-II codes associated with the accelerator pedal position sensor include:

• P2135 (Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation)
• P0220 (Throttle/Pedal Position Sensor/Switch Circuit "B" Malfunction)

Examine the accelerator pedal sensor, its electrical connections, and cables. Look for any visible sign of damage to the sensor or its wiring.

If you have an oscilloscope and multimeter, you can test the sensor for internal flaws. This job requires at least two people.

The price tag of a new sensor depends on factors like the year, make, and model of your car, the device’s brand, and the number of parts included.

On CarParts.com, an accelerator pedal position sensor can go for anywhere between $3 and $724. You can buy the component on its own or as an assembly.

Having trouble picking an accelerator pedal position sensor from the various offerings found at any car parts store? Just keep the following tips in mind.

Compatibility

Make sure the replacement part enjoys compatibility with your car. You don’t want to spend a significant sum on a replacement accelerator pedal position sensor, only to find out that it won’t fit in your vehicle.

Online auto parts shops like CarParts.com have a filter bar to help you quickly find replacement parts guaranteed to fit your car. Just enter your vehicle’s year, make, and model into the bar.

Individual parts versus complete assembly

An accelerator pedal position sensor contains a stator and a rotor. The stator itself uses an excitation coil, receiver coils, and an electronic evaluation unit.

If your budget can handle it, buy a complete assembly. Replacing the entire sensor costs more but reduces the risk of complications caused by incompatible parts.

An accelerator pedal position sensor displays high sensitivity to voltage. Individual parts that don’t work together correctly can cause electrical shorts and wear out the sensor faster.

The parts of a complete assembly got designed and assembled by the same manufacturer. This assures parts compatibility and performance.

Further, not all accelerator pedal position sensors work in the same way. It’s risky to use a part for one sensor model to repair a different model since the slightest difference in voltage can lead to a short.

Warranties

Always get a replacement part with a warranty. An accelerator pedal position sensor is a complex device with many electrical parts. It’s vulnerable to breaking down and difficult to repair, so a warranty will help ease your mind and wallet.

Standard warranties for these sensors last for three years of 36,000 miles. Read the fine print thoroughly and look for technicalities that can disqualify the coverage.