Check engine light on at startup

[Tim]

It's gotten into the teens out here, and in the morning when I go to start the car up, the check engine light comes on and it idles roughly for a few minutes. This only happens on really cold days. After that the light goes off, the idle smooths out, and runs awesome for the rest of the day.

Anything to worry about? I asked a friend and he thinks it might be the O2 sensor going bad.

Car is an '89 auto, mostly original.


Regards,

Tim

[FB71]

nope, not O2. Engine is still in open loop due to low coolant and exhaust temps. Could be a few different things. Pull the code set by the MIL, that should help.