Civic VX Check Engine Light Off then On
 

I've got a 92 Civic VX that we just bought with 151K miles on it. It's in great condition and runs great, however, when we 1st crank it there's no check engine light on. Then after a few minutes of warming up, the light comes on. I can turn the car off, crank it back and the light will be off until a few minutes later or until I push the RPM's up to 2 or 3K.

Any ideas? I'm about ready to buy an O2 but the one on the car doesn't look that old.

Nice thing about OBD 1 is you don't need a code reader to check engine codes. I would not buy an O2 until you check the codes. I just copied the following from one of the Honda sites

Here is the information you need to read error codes on 92-95 Civic and Del Sol (CRX). Those cars are OBD-I, so the same info should be usable for any OBD-I car.
There is a 2-pin (most likely green in color) connector by the ECU or somewhere under the passenger's side dash. It's a Data Link Connector. Connect it's two pins with a piece of wire. Watch out not to get jolted while you're connecting the pins.

You will read error codes on the gauge cluster, on the Malfunction Indicator Lamp. Turn the key to position "II" and watch the lamp blink. Error codes are reported by a number of blinks.

There are short and long blinks. Long blinks mean 10, and short blinks mean 1. For example, if you get "long-long-short-short-short", it means error code 23. There is a short pause between each flash (long or short) and a long pause between 2 error codes. There will always be long flashes before short flashes. So you cannot expect number 23 to be reported as "short-long-short-long-short".

Take note of all error codes reported by ECM (Electronic Control Module). Find a list online that explains "OBD-I error codes honda" and you will find out what your problems are.

Do not forget to remove the wire from the 2-pin connector once you are done.

Thanks turbothrush. So do you think the codes will show up even though the light is not on when it first gets cranked?

Probably...most codes get stored in memory. Good luck

Sounds like your problem is the the CEL is not clicking on before the car is started. I would look into that problem before determing you have a code.

edit:

I reread your post. Clarify if the CEL comes on and off before turning over.