Hi everyone. I have 95 GMC Xcap Z71 5.7L with 162k Miles. The Service Engine cones On and Off when I drive. I have not figured out a pattern to it. It started 3K miles ago. I am guessing is the Oxigen sensor. But I am sure it can be other things. Any easy suggestions where should I start debuging?
Thanks in advance.
DavidmZ71

Have Zone hook it up and read the code. I don't know if your truck is OBD1 or 2. If it's OBD1 you can check the codes using a paper clip... Do a search.

I would first take it to auto zone and get them to read the codes. I would think its the oxygen sensor since you 160,000 miles on your truck.

95 is OBD1, so check your codes.

Thanks. I did not know that Auto Zone can check the codes (for free)? Do I need to take it when the light is on other wise the error code may not be read? thanks, again.
David M,

Yes its free at Auto Zone.

Thanks Guys. I went to AUTOZONE, and got the little clip to read codes for OBD1. I got a code that had to do with the EGR Valve or Solenoid. I took the old valve out and took my chances. I replaced it with an aftermarket EGR valve that they sold me at Autozone (they gave me a discount because it was open) paid $15 dollars. The check engine soon light NO longer comes on!!! However, I do notice sometimes a slight hesitation in the truck when taking off. I don't know if its the new valve (meaning should I have bought the Dealer's one for $92dollars), does it matter?
I already changed the Fuel filter and the PVC valve. What else can it be.

thanks.
DavidmZ71