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  • Diagnostic Trouble Code (DTC) P0122 stands for “Throttle Position Sensor/Switch A Circuit Low Input.”
  • The powertrain control module (PCM) logs a P0122 code when the throttle position sensor “A” displays lower voltage than normal.
  • This fault can also indicate a problem with the electronic throttle pedal on newer vehicles.
  • The P0122 error code can cause issues like hard starting, hesitation, stalling, and surging.

When the Check Engine Light on your car’s dashboard lights up, it’s time to use a diagnostic scanner to determine what faults triggered the CEL. Typically, there are a variety of diagnostic trouble codes that could potentially be the culprit—and one of them is the P0122 code.

What Does the P0122 Code Mean?

Diagnostic Trouble Code (DTC) P0122 stands for “Throttle Position Sensor/Switch A Circuit Low Input.” The powertrain control module (PCM) logs a P0122 code when the throttle position sensor “A” displays lower voltage than normal.

As its name implies, the throttle position sensor keeps track of the throttle’s position. It is usually located on the throttle body, but this fault can also indicate a problem with the electronic throttle pedal on newer vehicles.

The signal from the throttle position sensor guides the computer in managing the ratio of air to fuel and the best time to trigger the spark plugs. The data also helps manage other parts of the emission system.

For an advanced, technical description of different configurations of throttle position sensors, read our discussion here.

To learn the possible causes of code P0122, read the next section.

What are the Possible Causes of the P0122 Code?

an automotive throttle body
The voltage of the throttle position sensor can drop below the expected range for several reasons.

The voltage of the throttle position sensor can drop below the expected range for several reasons, including the following:

  • A loosely-mounted throttle position sensor
  • Electrical short on the sensor circuit, either to the ground or to another wire
  • Faulty sensor
  • Faulty throttle position switch
  • Bad or corroded wiring or connections for the sensor
  • Issues with the PCM
See also  Bad Throttle Position Sensor Symptoms: What You Need to Know

What are the Common Symptoms of the P0122 Code?

As with any engine-related trouble code, the P0122 code will activate the Check Engine Light.

Other symptoms include:

How to Diagnose the P0122 Code

Figuring out exactly what triggered the P0122 code can be tricky. You can leave the job to your mechanic or you can try to do it yourself with the help of a detailed guide.

You can check out the video below to help you understand how to diagnose the code properly:

How to Fix the P0122 Code

The sheer number of possible causes that could trigger the P0122 code means there’s no single way to fix it. Most people leave the job to their mechanics, but you can fix it yourself if you’re confident enough in your automotive DIY skills.

If you’re a beginner, make sure to do your research—and there are plenty of online auto repair resources and guides to help you do that. We also suggest getting an ALLDATA single-vehicle subscription (which would be specific to your vehicle) for this and all future repairs your car may need. Also, do consult your owner’s manual before you begin working on your car.

As mentioned, you won’t find a definitive fix for any code. You’ll have to figure out the underlying cause, then do your research on what fixes have worked to clear the code. Keep in mind that some fixes may only work for certain makes and models, and not for others.

For example, replacing the PCM or VCM and repairing the throttle position sensor are some of the fixes that have been confirmed to work for various model-years of the Chevrolet Blazer. However, they may not work for other vehicles that are displaying the P0122 code.

Other Notes About P0122

Several OBD-II trouble codes also cover the performance of the throttle position sensor at the “A” position. They are:

See also  P0068 Code: MAP/MAF - Throttle Position Correlation

A Closer Look at Throttle Position Sensors

Throttle position sensors on older cars with cable-operated throttles are a single analog (not digital) unit mounted on the throttle plate shaft to provide throttle angle position to the ECM/PCM. Vehicles with an ECM (which controls only the engine) and TCM (which controls the transmission) rather than a PCM (which controls both engine and transmission) will usually (not always) have two TP sensors, one for the transmission control module and the other for the engine control module.

Early Asian and European vehicles sometimes have an analog TP sensor that includes an idle tracking switch (digital input) that closes or opens when the throttle is released to track when the vehicle should be idling. The ECM/PCM can use the idle tracking switch compared to TP sensor voltage to determine if there is an issue with the sensor – if the idle tracking switch indicates idle but the TP analog portion of the sensor indicates otherwise, a code is set.

This potentiometer type analog sensor has a moveable contact connected to the throttle valve that slides on a resistive strip, and the closer the slider moves toward the wide open throttle, the nearer it is to the 5-volt end of the strip,  the higher the voltage. Likewise, the lower the slider moves toward the signal return end of the strip, the lower the voltage. Voltage at idle is typically from .5 to 1 volt and at wide open throttle it will be 4.5-4.7 volts. This varies slightly between manufacturers.

With the advent of Electronic Throttle Control, which some will call “drive by wire,” putting the ECM/PCM in charge of throttle angle made it expedient to have redundant TP sensors; more than one sensor in each spot – usually with two or three TP sensors on the Accelerator Pedal assembly (called AP sensors) and two or three TP sensors on the throttle body.

Most throttle position sensors are potentiometers – a three- sensor with a reference voltage (5 volts), a signal return (ECM/PCMground), and a TP signal wire between those voltage and ground feeds that changes voltage with throttle position. On systems with redundant TP sensors, the two or three sensors don’t all produce the same voltage at the same time – some have the sensor voltages “mirrored,” if you watch them on a scope.

See also  P0123 Code: Throttle / Pedal Position Sensor "A" Circuit High

Other systems have the sensors reading various different voltages that are expected to follow certain parameters. Some sensors in a redundant array might top out at .75 volts while other sensors might top out at over 4 volts, with a third sensor topping out at 2.5 volts.

, P0122 Code: Throttle Position Sensor/Switch A Circuit Low Input

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Most vehicles still use potentiometers, but some, (like Toyota) are now using Hall Effect (non-contact) TP sensors, which uses more wires and a magnetic device within the sensor to make it less likely to wear out.

diagram of electronic throttle body and accelerator pedal with sensors colored
The accelerator pedal and throttle body in this illustration have only two redundant potentiometers, but there are many newer platforms with three potentiometers on one or both of these components. | Image Source: Richard McCuistian.
accelerator pedal sensor array on a 2006 ford explorer
An accelerator pedal sensor array on a 2006 Ford Explorer. Notice how the sensors have different voltage ranges and that one of the sensors mirrors the other two rather than simply following them. This array provides a reliable way of using the expected rationality between the redundant sensors to reveal a fault in just one sensor. | Image Source: Richard McCuistian.

How to Get a Quality Replacement Throttle Position Sensor to Fix the P0122 Code

A bad throttle position sensor can trigger diagnostic trouble codes like the P0122 code. If ignored, the bad sensor causes issues like idle surges, stalling, and hesitation while accelerating. Before the situation gets worse, order a quality replacement throttle position sensor here at

There’s no need to step out of the comfort of your home and wait in a long line to get a new throttle position sensor. Simply plug your vehicle’s year, make, and model in our website’s built-in vehicle selector to bring up quality products from brands trusted by drivers across the country. adds to the convenience by stocking its parts in strategically positioned warehouses, so you don’t have to wait long before your order arrives.

Don’t wait to replace a faulty throttle position sensor! Check out our wide selection of throttle position sensors and enjoy low prices on quality products!

Products Mentioned in this Guide

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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Ann Averill

I got code p0122 then p0123 than p0456 p1648 than it said done. 2001 dodge Caravan sport

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