How to Spot & Fix a Faulty Accelerator Position Sensor

symptoms of a bad accelerator position sensor

A modern car consists of many sensors and electronic systems. In the earlier car models, the accelerator pedal and throttle system were connected via wiring. However, modern vehicles have accelerator pedals connected to the throttle with sensors.

The accelerator pedal position sensor (APPS) sends the speed, position and pressure to the electronic control unit (ECU). It is also called a drive-by-wire system. However, what happens when it fails? A driver may detect signs and symptoms of the bad accelerator position sensor.

Let’s learn about the malfunctioning accelerator pedal position sensor symptoms and how to reset and replace it.


different signs of a failed acceleration position sensor
If you feel sluggish acceleration or not enough power when accelerating the vehicle, it may be due to a failing accelerator position sensor

The accelerator position sensor transmits the speed and position information of the accelerator pedal to the car computers. The ECU transfers the load requested by the driver’s foot on the pedal. However, you may see symptoms of a bad accelerator position sensor when it malfunctions. 

A failing accelerator position sensor can be the cause of the check engine light on or uneven acceleration. Let’s learn more about the signs of a bad accelerator position sensor.

Uneven Engine Idling Speed

Engine speed should be 600 to 700 revolutions per minute at idle. However, a symptom of a bad accelerator position sensor is causing the engine to stall at idle. 

A failing accelerator pedal position sensor will not send accurate information to the ECU. It results in uneven fuel delivery causing uneven engine idling speed. Additionally, a malfunctioning APPS can be a reason behind inaccurate signals to the throttle position sensor, resulting in RPM fluctuations while driving.

Car Hesitates When Accelerator Pedal Is Pressed

car hesitates when accelerating the car
A failed accelerator position sensor can cause hesitation while accelerating the car

A car driver can instantly identify when the car hesitates when pressing the accelerator pedal. It is one of the common signs of a bad accelerator position sensor when it doesn’t send the correct signals. Incorrect fuel delivery can be a cause of sluggish car acceleration.

If the acceleration feels sluggish, one must drive to the mechanic and get the car inspected. Moreover, the car driver can accelerate up to a certain speed when the APPS fails. This symptom of a bad accelerator position sensor doesn’t send the correct pedal position to the ECU, causing the car to not speed beyond even when the pedal is fully pressed.

Check Engine Light

Any sensor malfunction causes the check engine warning light. When it comes on, you must check the car using an onboard diagnostic (OBD) scanner. It will show the code related to the malfunctioned sensor. In case of sluggish acceleration, it may be a sign of a bad throttle position sensor or APPS.

Car Limp-Home Mode Comes On

Limp mode is a car security feature that turns on when the sensors or transmission fail or the fluid level is low. Similarly, it comes on when there is an accelerator position sensor issue. It results in a check engine or other warning lights on the car dashboard to alert the drivers and take precautionary measures instantly to avoid mishaps.

Gear Shifting Problems

Gear shifting failure due to accelerator position sensor
One may face gear-shifting problems due to APPS malfunction

While insufficient transmission fluid or clutch failure can cause problems in changing gears, it can also be due to accelerator position sensor problems.

Replacement Cost of the Accelerator Pedal Position Sensor

When the driver detects any symptom of a bad accelerator position sensor, they must replace it. The replacement cost of the accelerator position sensor may vary depending on the vehicle model. Generally, APPS replacement will cost between AED 500 to 1500.


resetting APPS problem in car
You can test and reset the APPS if you detect any symptom

What Causes Acceleration Pedal Position Sensors to Fail?

Since the accelerator pedal is the most pressed component, its wiring or sensors can get disturbed. The main causes of accelerator pedal position sensor failure are damaged cables or connections, missing voltage and ground supply or faulty electronic evaluation unit in the sensor. In either case, you must diagnose the problem and get it repaired sooner for efficient car performance.

How to Reset the Accelerator Position Sensor?

You must disconnect the car battery and connect it after a few minutes. After that, turn on the car ignition system and press the accelerator pedal. Then, release the accelerator and turn off the engine. Recalibrate the accelerator pedal position sensor and find out if it solved the problem.

How Do I Test the Accelerator Pedal Position Sensor?

Firstly, check the accelerator pedal position sensor voltage using an ammeter. Press the accelerator pedal and check the voltage. If the voltage values don’t match the manufacturer’s recommendations, perform car diagnostic tests and scan for the codes.

Is Accelerator Position Sensor Same as the Throttle Position Sensor?

No. Both have different functions. A throttle body position sensor monitors the amount of fuel required by the vehicle, whereas the APPS gives signals to the ECU about the position and pressure of the accelerator pedal to speed up or down the car.

That wraps around the symptoms of a bad accelerator position sensor. If you buy a used car in the UAE, you must get the vehicle inspected before deciding. Moreover, always set a car maintenance schedule to avoid the causes of common car problems in the future.

Keep reading the leading autos blog by dubizzle, where you find car problems and the solutions to fix them.


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