What is an EGR valve?

Hi,

EGR stands for exhaust gas recirculation. the EGR valve allows a specific amount of exhaust to re-enter the engine combustion chamber via the intake. The ultimate goal is to reducing NOx gasses from entering the atmosphere.

Based on your description, start by checking for engine vacuum leaks. This can cause the vehicle to idle poorly and shifting issues.

Here is a link that shows how to check for leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, you may want to consider having the can-bus system scanned. CAN stands for controller area network. This network connects all the modules/computers together via a few wires. By scanning the can-bus, it will identify codes from any of the modules.

Here is a video showing how it's done:

https://youtu.be/InIlnsjOVFA

In all honesty, that is where I would start.

Let me know what you find or if you have other questions.

Take care,
Joe

Well, I have OnStar on my car and I get a monthly diagnostic email to me and this is one of the things that they check every month to make sure it's running correctly and that was fine. so I am still kind of confused, but I will look at your links and I will take them into consideration. thank you so much.

Is that the same thing as a purge solenoid? that's what I think then after I shut my car off I hear clicking and like a little electric motor about 5 minutes later coming like behind the steering column.

Hi,

The purge solenoid is different. Although it is also part of the emissions system, it has a totally different job. A purge valve or solenoid allows gas fumes to enter the combustion chamber when the engine is running at specific conditions.

Gas vapors are produced by the fuel in your vehicle. The evaporative emission system (EVAP) is responsible for preventing fumes from entering the atmosphere. The fumes are stored in a charcoal canister. When conditions are right, the purge valve/solenoid opens and allows the fumes to be drawn into the engine and burned.

I hope that makes sense. LOL Let me know. Also, let me know if you have other questions. I attached a pic of the purge valve below.

Take care,

Joe

See pic below.