suburban

99 sub w/75k miles
This light comes on intermittently.
Specifically when climbing grades @ high RPM
this has been doing is on & off for approx 20K miles
It would go off within a day off it's occurrence and I figured it was poor spark at high speed.
Had to get it smogged (CA thing). It passed all output parameters with the exception that the test picked up an OBD fault. Chk Engine Light.

Had to take it to the dealer to be diagnosed. They indicated that the problem lies in the 5th piston misfire at high speed under stress.

the fix .... hone valve guides $2000.00

I have performed meticulous maintenance and always changes oil between 3 to 5K
I can’t believe this is the cause.
secondly- is there a way to reset the light/history so I can get the smog cert? dealer say's must fix prior to resetting.
My position is it doesn’t effect normal smog requirements-
I need more time to look into the alternatives but need the smog cert now.

Any suggestions?

right before you have it smog checked, you could disconect the battery cable for about a minute. That should wipe out the codes, but it's also gonna take out presets in the radio, and a few other things

Perhaps you could be more specific with the subject line ... this is in the Suburban threads ... far more likely to get responses, I think.