Accelerator Pedals & Sensors

What Are the Accelerator Pedal and Position Sensor and Where Are They Located?

In older vehicles, the workings of the throttle were pretty simple.  The accelerator pedal (also known as the gas pedal, the throttle pedal, or the loud pedal), was connected to the throttle by a wire cable.  When you mashed on the loud pedal, it pulled the cable, and opened the throttle valve, letting more air into the engine.  That brought in more gas and led to the production of power and glorious engine noises. 

This system was simple enough, but it had one major flaw.  If the cable snapped, the throttle would be stuck, and you wouldn't be able to drive the car. 

So, modern car designers came up with more sophisticated electronic throttle control, sometimes called drive-by wire.  This system relies on an electronic sensor called the accelerator pedal position (APP) sensor.  The accelerator pedal position sensor is attached to the accelerator pedal and can sense what position the pedal is in.  A change in the position of the pedal leads the sensor to change the electric voltage it supplies.  That voltage is carried to the Engine Control Module (ECM), or the car's onboard computer.  The ECM then sends a signal to the throttle body motor to tell it how far to open the throttle valve.  There may actually be more than one sensor inside the sensor assembly so that there is a backup if one fails. 

How do I Know if my Accelerator Pedal or Position Sensor Needs to be Replaced?

Like any electronic part, the APP sensor can develop problems with its internal wiring or circuitry over time.  If the accelerator position sensor stops working then the ECM won't have correct information about what kind of pressure you are putting on the gas pedal. This might make acceleration difficult or may lead to stalling. 

If there are multiple sensors and they don't agree, then the ECM will recognize that one of the accelerator sensors has failed and will usually put the engine into a failsafe, "limp home," mode. You will also see the check engine light illuminate at this point. A diagnostic scan tool will show codes between P0220 and P0229 for accelerator sensor problems, as shown below.

Related OBDII codes

P0220 Throttle/Petal Position Sensor/Switch B Circuit Malfunction
P0221 Throttle/Petal Position Sensor/Switch B Circuit Range/Performance Problem
P0222 Throttle/Petal Position Sensor/Switch B Circuit Low Input
P0223 Throttle/Petal Position Sensor/Switch B Circuit High Input
P0224 Throttle/Petal Position Sensor/Switch B Circuit Intermittent
P0225 Throttle/Petal Position Sensor/Switch C Circuit Malfunction
P0226 Throttle/Petal Position Sensor/Switch C Circuit Range/Performance Problem
P0227 Throttle/Petal Position Sensor/Switch C Circuit Low Input
P0228 Throttle/Petal Position Sensor/Switch C Circuit High Input
P0229 Throttle/Petal Position Sensor/Switch C Circuit Intermittent

It is possible to check an APP sensor with a digital voltmeter. You will have to remove the accelerator pedal assembly from the vehicle, hook it up to the voltmeter and try working the pedal. The voltmeter will show smooth voltage changes if the accelerator sensor is working correctly.

Can I Replace the  Accelerator Pedal or Position Sensor Myself?

At this point you may be thinking that this part is highly complicated, and in some ways it is, but it shouldn't be too difficult to replace. In some cases, you may be able to buy an entire new accelerator pedal assembly. In that case, you will have to disconnect the wiring harness, unbolt the old pedal assembly and install the new one. Otherwise, the process will be similar, except that you will have to remove the old sensor from the pedal assembly and swap in the new one. 

Need a Replacement Accelerator Pedal Position Sensor?

Your vehicle’s APP sensor ultimately controls fuel flow in your car or truck. If it is malfunctioning, your vehicle may experience problems such as poor acceleration and reduced vehicle speed. Don’t let these problems happen to you – shop at 1A Auto for a high quality replacement! We carry aftermarket accelerator pedal sensors for many makes and models, and at great prices.

At 1A Auto, we make shopping for a replacement accelerator pedal position sensor for your car, truck, SUV or van easy - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our sensors, warranty, compatibility or to purchase, or you can buy online.