SES light just comes on and then goes off

[birddogenu]

I have an 87 350TBI. SES light will just come on after driving a while, and stay on then sometimes just go off, then come back on sometimes soon and sometimes it takes a while . I'm cornfused Any ideas of where to start ?

 

[CSFJ]

O2 sensor possibly? I've got an '88 silverado that does the same thing right now. The codes I keep getting are for the O2 sensor. replaced it once, still happens. A previous owner ran true dual exhaust on it and eliminated the catalyst. Can't see why it would matter though. The early injected motors ran the O2 sensor in the exhaust manifold ahead of the cat.

 

[birddogenu]

Thanks a lot. That's kinda what I was thinkin too. I appreciate your reply !

 

[Rusty Nail]

GM C3 emission computer only turns the light in while a fault is ACTIVE. Meaning your problem is intermittent. However, the associated trouble code(s) ARE STORED in computer memory. While intermittent problems can be a PITA, retrieving the associated code(s) will produce a place to start from.

Given lack of information, I still guess TCC, EGR solenoid, OR EVAP related.

 

[chengny]

Some detail on the SES light:

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