If you’ve ever experienced issues with your vehicle’s electronic throttle control, you know how frustrating it can be. The check engine light comes on, you take it in for a scan, and you’re hit with the P0121 throttle position sensor code. But fear not, because in this guide, we’ll show you how to replace a bad electronic throttle on your vehicle.
On this Silverado, the check engine light was on, and the code was P0121 throttle position sensor. While this code can theoretically be a few different things, on this vehicle, it’s a design flaw – the throttle bodies go bad all the time. So, we’re going to change it out.
The throttle body is pretty easy to get to. It’s at the top of the engine, and all you need to do is loosen the clamp, wiggle it a bit, and unbolt it. Then, you have to unplug the electrical connection. There’s a plastic tang that you’ll have to pry off first to loosen it, and then the whole thing pops off. Finally, unbolt the four bolts that hold the throttle on, and off slides the throttle assembly.
Once you have the old throttle assembly off, you can get the new one. Make sure you get a good one, and try to get a new one rather than a remanufactured one – they aren’t as good. Slide the throttle assembly over the new gasket and bolt it back on snug. Then, plug the electrical connector back in and snap the plastic piece in so it locks. Slide the air duct back on, and tighten the clamp so you don’t have any air leaks.
Now, here’s the part you’re not going to like. You can start the car up, but you’ll notice it idles way too fast. This is because it has to go through an idle relearn process. These vehicles are designed so that if you need to go to a mechanic, they can hook up a fancy scan tool and perform this idle relearn process so it runs right. It’s a rather involved process that tells you how to run the vehicle to reset it. Once it’s reset, start it up, check a few things off, and you’re good to go.
It’s a shame they got to make them this complicated, but that’s modern engineering for you. So, the next time your electronic throttle body goes bad, why not fix it yourself – at least most of the job. If you need a mechanic to reset it, that’s okay too. Just remember, if you have any car questions, visit the Scotty Kilmer Channel, and we’ll answer them as soon as possible.