As Hw says it could be a connector. check all teh under bonnet connects, disconnect them, check contacts & reconnect. Do 1 at a time. If you find one that is corroded, clean the contact with a little sand paper, Or 1 of your wife's/girlfriend/some bird you know, Emery boards cut in to small strips.
Disconnect the battery for 30 mins. This will reset the ECU.
Then start her up & see if the light comes on ? If it does get a dealer to check the car with the test equipement.
I've solved to engine lights with this method, hope it works for you
2x 145, 4x 75, 4x Sprints,a 156, 146 now a 155