I have a 1995Chevy Silverado 1500, 5.7 Automatic. Didnt pass smog. "Service Engine Soon" light comes on/off. Took it in for a diagnostics. Was told to change the O2 sensor, said it was running slow. Also to change EGR valve, did that. Just drove it, AND THE LIGHT CAME ON AGAIN!!! I cant smog it! Please help with suggestions......

 

Get a PO box in another state.

 

i second that

 

Stop running the cheap '87 octane in it......

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Scott - do you have anything aftermarket.....exhaust/filter.....Can they tell if your cats are bad?.....did you pass last year?

 

87 has a more complete burn than 93. It burns faster. 93 burns hotter and slower with the possibility of an incomplete burn and moretoxins to pass though the exhaust.

 

yeah if the code was about your 02 sensors i'd check the catalytic converters

 

cheap gas would not be the problem