oh, OBD I...sorry can't help you there.

the CEL lights up during initial ECU boot up and some sort of system self-diagnostics...

but your description of during cold weather doesn't fit your IC/ECU theory that it's bad. some sensors/switch/relay may be getting moist on cold, rainy days thus the intermittent problem. capacitors are designed to tolerate temperatures. how about looking at places that get wet/moist on rainy days?