Service engine soon light keeps coming on

Maintenance/Repairs
1

I have a 98 GMC Sierra 4x4 with a 5.7 Vortec engine and 145,000 miles on it. My service engine soon light keeps coming on and the code is for a bad EGR valve. I have put 4 on in the past year. The local GM dealer didn’t seem to excited about it. Has anyone else had this problem. Thanks

2

Those codes never tell you that a specific part is bad. They point to problems somewhere in the system, so they are starting points for diagnosis. Of course, one way to diagnose is to start replacing parts - but as you now know that is the expensive way. But consider one part done - you can now be pretty darned sure that your EGR valve itself wasn’t the problem - so that the problem must lie elsewhere in the EGR system. There is usually a sensor & a solenoid in this system in addition to it being a system of pipes that get clogged. (when you replaces the EGR did you happen to clean out the passage to the intake?)

There are lots of codes for the EGR system - do you have the actual code(s) that came up? If so, post it/them and folks might be better able to help.

I don’t know the specifics of the EGR system on this vehicle and so can’t give you anything specific on the best way to troubleshoot it (maybe someone else can), but you can have a look at this as it may help:
http://www.aa1car.com/library/egr.htm

3

If the EGR valve keeps “going bad” then you have one of two problems.

1- EGR regulator is bad
2- intake pipe to EGR valve is clogged with soot.

Experience says #2 is usually the culprit.

4

I have the same truck and when my code said EGR my mechanic just replaced the screen (or cleaned it, I can`t remember) and everything’s been fine for the last 25,000 miles.

5

Thanks for the swift responses. I forgot to mention that the light goes out on occasion and then comes back on. No rhyme or reason to it. Once I drove over the edge of the curb and it went out only to come back the next time I started the engine. Thanks denny64