I have a 2003 chevy impala i changed the egr valve and my check engine light is still coming on and a part store read my code and it said egr valve what else could be the problem

Clogged EGR valve<utube src="ZiAuEKWMyNM" ></utube> when I had that problem this is what it was

You use Google to look up the codes,
& solutions & don't use it until properly
diagnosed & resolved

P0171 and P0174 are lean codes. There is likely a large vacuum leak or the MAF is bad.

Try starting the car and wiggling the connector for the MAF sensor. Also try tapping the MAF sensor. If the idle changes or the car stalls replace the MAF sensor.

The second shop should recognize that these codes don't have anything to do with the ignition module.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Okay a few things to check first, with car off, turn key to on position but do not start, does the check engine light light up, failed bulb? run codes anyway, most chain auto stores will do for free, check transmission fluid it it dark, burnt smelling? how many miles ? when was transmission serviced if ever? did you check spark plugs are they worn out? fuel filter changed if over 50k miles could be blockage and resettles when sitting. lots of things could case this issue, i would check light and codes first.

Doesn't work that way

Diagnostic Codes, do not tell you
what is wrong or what to replace

You use the codes to find the system issues
first.

Check engine lights can mean a number fo different issues. I would recommend that you have the codes read from the computer and this will determine what causing the light to come. Most auto parts store take code reads for FREE!

first repair the egr valve. it will cause all sorts of problems

I suggest changing your egr valve. I have a 03 impala with the same problem and check engine light came on and through the code for the egr valve. they are 154 at autozone

there are a couple of things, first make sure there are not restriction in the exhaust, i know the dealer has had to replace converters under warranty because of this problem, then theres a reflesh program for the computer due to this problem, and lastly,run with egr off make sure it clean of carbon,carbon gets stuck in pintle sets check eng lightbut carbon then blows by so when you remove egr you see nothing, well start with these good luck.

Wow, I just went through the same problem and guess what it was a clogged converter and a bad oxyegen sensor. The garaged fixed it up for me by putting an eco converter on it and a new O2 sensor. I have a 2003 Chevy Impala,V6 3.8 engine. Good Luck!!!!