What Does the Engine Code P2122 Mean?

If your car is showing the P2122 engine code, you likely have a low voltage in the throttle position sensor.
Written by Talullah Blanco
Reviewed by Melanie Reiff
If your car is showing the P2122 engine code, your car’s throttle position sensor has low voltage. You’ll want to promptly take your car to a mechanic before you have no throttle pedal response. 
Your car’s computer system stores diagnostic trouble codes (DTC) when something goes wrong to help you identify the problem and find the solution. Owning an On-Board Diagnostic (OBD) reader will allow you to run DTC reports and monitor the health of your car, but it’s important to
understand what those car OBD codes mean
to protect your vehicle. 
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What does the engine code P2122 mean?

Definition: Throttle/pedal position sensor/switch ‘D’ circuit low
Engine code P2122 indicates your vehicle’s onboard computer system has detected low voltage in your throttle position sensor. 
The throttle position sensor is used to measure how open the throttle valve is and how much fuel is demanded by your engine. 

How much will it cost to fix?

If you need to repair or
replace your throttle position sensor
, the final price will depend on the cost of labor per hour, which can vary depending on the
make and model
of your vehicle. Most
car repair
shops charge $75 to $100 to repair your throttle position sensor. 

What can cause the P2122 engine code?

Your car could be showing the P2122 for a number of reasons—from a faulty accelerator pedal position sensor to a faulty powertrain control module.
If the cause is a faulty accelerator pedal position sensor, then it is most likely open, shorted, or has a poor electrical circuit connection. The accelerator pedal sensor transmits the position of the accelerator pedal to the engine control unit, so you can drive immediately. 
The powertrain control module is your vehicle’s brain. It manages the engine, transmission, and other systems based on the information it receives from sensors located around the vehicle. If the PCM is causing the P2122 engine code, you’ll want to bring your car to a trusted mechanic sooner rather than later.  

Common symptoms of the P2122 engine code

Other than your check engine light or service engine soon warning light being on, symptoms of a P2122 include: 
  • Rough or low idle
  • Car engine stalling, surging, or misfiring
  • Little to no acceleration

How serious is the P2122 engine code? 

If your car is experiencing symptoms from the P2122 engine code, the throttle position sensor is likely not working. 
The throttle position sensor controls the shifting of the gears in your car. If the sensor stops working, the car’s computer cannot calculate how much fuel should be injected into the system, and your car may not even start. 
You should check the throttle position sensor, and if necessary, repair or replace it immediately. 
Key takeaway: Take your car to a trusted mechanic if your car is having driveability issues.

Can I fix the P2122 engine code myself?

Before you try to fix the P2122 engine code at home, it’s important to properly diagnose the problem. To find out what’s causing your car to display the P2122 engine code, it’s recommended that you check the throttle position sensor for:
  • Visually inspect the related wiring harness and connectors 
  • Check for damaged components
  • Look for broken, bent, pushed out, or corroded connectors’ pins
Your throttle position sensor is an important component of your car. If you’re not sure how to repair your car, bring it to a mechanic for a thorough inspection, repairs, or replacement. 

Replacing the throttle position sensor

If you choose to replace your throttle position sensor after inspection, your mechanic will likely follow these steps:
  • Scan the computer system for diagnostic trouble codes
  • Test the throttle position sensor and its related wiring
  • Remove and replace the faulty throttle position sensor
  • Clean the built-up carbon from the throttle body
  • Re-install the throttle body and reset minimum idle to factory settings
  • Clear trouble codes 
  • Test drive the vehicle to see if it is operating properly
If you notice your gears not changing properly or your check engine light is on, get your throttle sensor inspected by a trusted mechanic.

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