1995 Z28-A4: SES light comes on when car is almost warmed up in neutral (fans also come on so I know the car perceives something's wrong.) Put car on gear and after 4-5 seconds it goes off. Put back in neutral and after another 4-5 seconds it comes on again. Car runs fine, plenty of power, no apparent miss. I don't currently have a scanner (working on that). Car has cai with descreened maf. I originally thought having the screen out was causing the problem, but it happens in the same manner with the maf screen either installed or removed. Any Ideas? Thanks!

 

you camt really guess to whats wrong when the SES light comes on, you are correct something serious is wrong since the fans are coming on

 

O2 sensor.