Yours will probably be the same as mine was. Although the lamp is working fine it will throw up an warning when it does the check. You'll find the lamp holder is corroded like mine was. If you look under the bottom of the fog light behind the bumper you'll see a large circular cover. That is the access to the lamp holder, you'll probably find it's corroded by water getting into to it (maybe if like mine, you have a cracked lens). The system test the lamps by sending a low level electrical charge through the wiring to test the lamp. If it gets a certain resistance then I assume it flags it up thinking the lamp has failed whereas it actually works.