- A Chevy P0121 Code Silverado is a “Throttle Position (TP) Sensor 1 Performance.”
- Common causes include a faulty throttle body, bad throttle position sensor, and wiring.
- Symptoms include the engine running badly, rapid RPM changes, and possibly limp mode.
If you have a Chevy Silverado and get a P0121 error code, there is a problem with the throttle body.
An OBDII scan tool will give the error as “Throttle Position (TP) Sensor 1 Performance.”
Some scan tools will give the error as “Throttle Pedal Position Sensor Switch (TPS) A Circuit Range Performance Problem.”
What is a P0121 OBDII Error Code?
A P0121 error code is “Throttle Position (TP) Sensor 1 Performance.”
The computer (ECM/PCM) is not receiving data on the location of the throttle body.
This information is needed for the computer to calculate the air and gas ratio mixture.
Symptoms can vary but rapid RPM changes are common, and possibly limp mode.
3 Causes and Fixes P0121 Chevy Silverado
- Dirty or Bad Throttle Body
- Bad Throttle Position Sensor
- Wiring Harness Has Open or Short
When a Silverado has a P0121 code, the usual cause is the throttle body.
Most often, it is dirty and simply needs to be cleaned but can also have damaged components.
The first thing to do is to clean the debris and gunk out of the throttle body to see if the code will clear.
The inside can get a build-up of black gunk that can cause an issue.
After cleaning the unit, If the error will not clear or comes back, there is likely another problem.
Throttle body cleaner can be bought at an auto part store or online that, along with a clean rag, can be used to clean the unit.
A bad throttle position sensor will also cause a P0121 error code.
The computer (ECM/PCM) receives data from the position sensor.
When the sensor goes bad, the ECM will think there is an issue since the sensor is sending bad data.
The position sensor is located on the throttle body and is held in place with clips.
It is replaced by removing the harness and clips.
Replacing the throttle position sensor is a DIY task, but if in doubt, be sure to take your vehicle to a professional.
If the throttle body is cleaned, the sensor replaced, and the error still comes back, there may be an issue with the wiring.
While rare, a bad pin on the harness or a cut wire can cause problems.
Examine the harness and the pins going in as well the wires for any bad connection or a cut on a wire.
Summary
A Chevy Silverado with a P0121 OBDII error code has a dirty throttle body, bad sensor, or a wiring problem.
The official definition is “P0121: Throttle pedal position sensor A circuit range performance”.
Each component will need to be gone through to see which is the problem.
The first component to check is the throttle body which is usually dirty and needs to be cleaned.
A dirty throttle body is the most common problem, with the error usually clearing after a good cleaning.
If the error does not clear, the throttle position sensor can also cause issues and should be replaced.
If all the above does not work, there may be a wiring problem with a shorted or open wire causing problems.
Have you had problems with a Chevy Silverado and P0121 OBDII error code? Let us know your thoughts below.
I have fixed this same problem 14 times, and am on number 15. No one can figure out how to fix the problem. Every time truck gets wet the throttle sensor goes bad and sometimes not even when it rains. I keep truck in garage and since 2011 purchase have not driven much, because it’s always on low power mode. Anyone know how to fix this?
Hi how’s it? I have a 2011 Chevy Silverado and I am having this error code. So I cleaned the throttle body. It was filthy. I replaced the TPS with a AC Delco TPS. Now when I start the truck the idle speed goes up to 3000 and won’t slow down. I disconnected the battery for a couple of minutes and it is still doing the same thing.
What did you do? I have the sam issues
How did you fix this issue?
I have a 2007 ltz code p0121 comes up only when i start it