You have ridiculed every answer…every piece of advice. Why should anyone tell you how to check for causes of lean air/fuel conditions? It’s covered in any repair manual.
Wrong again, let me see, I have used prior advice.
“I used a standard code reader. i don’t remember the actual code, but VAGCOM seems to be what I need to look for in a mechanic. To answer the other questions, Very shortly after getting the radio installed the check engine light came on, 1st it was for the water pump (or that’s what VW service center told me), then about 3 weeks later the light came on again and that is where I am now.” Where is the ridicule?
For the radio: Each speaker has an amplifier attached. I tried to get a set of infinity speakers installed and couldn’t. No subwoofer. I have never tried with the radio off but the volume all the way down. The only difference is the flickering with the beat. Where is the ridicule?
The only thing after market on this car is the radio. Where is the ridicule?
AGAIN
I ASKED "“What should I look at next to avoid changing the EGR and or the MAF sensor?”
You answered with “Now, the EGR valve and MAF sensor are on your suspect list. Why? If you suspect them, or any component, test and check them. The instructions are in any repair manual (Haynes, Chilton’s, etc.).
Are you a dedicated parts changer, or, are you willing to do some troubleshooting? Which way will fix your car?”"
Now thank you Hellokit for making me waist my time and not trusting anyone on this site. A bit of advice before you bash someone about answers. Maybe you should read what the question is so you can answer it correctly and avoid looking REDICULOUS.