Top Check Engine Trouble Codes 2007-14 GMC Sierra 3500 Truck

In this video, we're going over some of the top reasons why your check-engine light might come on, on this 2007 to 2014 GMC Sierra 3500 HD.

The first code is the P0121, which is related to the throttle body, located right here. What the throttle body does is it allows more air or less air to enter into the engine. And, when you step on the accelerator, it opens a flap and closes the flap based on what the input is from you and the computer system. The reasons why these might fail is because of carbon build-up on the back of the flap or the back of the butterfly. And, that will cause not as much airflow to go into the engine when the vehicle is idling, and the computer notices what's going on. The other thing is, something to do with the sensor, which is on the side of it. If there's a problem with the sensor, there may be a different code. In some instances, if you get the P0121, you may be able to clean the throttle body and that'll take care of it, otherwise, you've got to replace the whole throttle body.

Now, we're gonna talk about the P0171 and P0174, which is related to the mass airflow sensor located right here. What the mass airflow sensor does, it actually monitors how much air is going into the engine versus the throttle body where it allows more air into, this just monitors how much is going in. If you see that any of these clamps are loose, right here or right here, and there's air flow getting into the engine without going by the sensor, that's gonna cause some issues, make sure you have a nice, clean air filter. When you have the airbox up, take a look at the mass airflow sensor and make sure there's no leaves or debris on the mass airflow sensor. That could cause an issue. If all those check out, more likely than not, you need a mass airflow sensor.

The last code we're gonna talk about is the P0325, and that's related to the knock sensors. On this engine, the knock sensors are located right here, and there's also one on the complete opposite side next to the starter. Whenever you get these codes, it's a good idea to check out the wiring harness, make sure there's nothing broken, make sure there's nothing loose. But then, most likely, you need a new knock sensor. They're not that hard to replace. Disconnect the connector, take that bolt out. When you put the new one in, it's important to torque these to the proper spec.

So those are the top codes that are gonna turn your check engine light on, on this GMC Sierra 3500 HD. If you enjoyed this video or it helped you out, make sure you subscribe to our channel. Ring the bell, turn on all notifications so you don't miss any of our videos.