If the battery is disconnected for a while, 30 minutes or so, the next restart will not have the CEL illuminated. Note that you will need the radio code and the station presets.

Then the computers wait until a certain set of driving things are done - certain miles and certain gears and speeds - to "re-set" the system. At that time it will "look for" problems and light the CEL if one is found.

Check hoses around the charcoal cannister and around the fuel filler tube area.

I understand that one hose from the charcoal canister is open to the atmosphere and can be a attractive place for an insect to nest. I've never found that open end, but the info source is credible. Note that the canister on the 1998 S-V/90 models can be under the front passenger's feet rather than below the windshield washer fluid reservoir.

Good Luck,

Bob

:>)