It was a bit of a surprise when the warning indicator for failed rear fog light illuminated last week. I have rear fogs but never use them, so I was pretty sure the bulbs were fine. They are. Both lights work exactly as they are supposed to, but I still get the warning every time I start the car.

It's a 2010 MCS. Does anyone know how to address this?

 

It could be the bulb/connection for your plate marker, in the rear hatch lift handle.

 

There is a secret way to see what lamp is out using the stalk button. Check this out

://www.northamericanmotoring.com/forums/r55-clubman-talk-2008/240462-lamp-out-lamp-on.html

 

Thanks for the tip on interrogating the OBD.

My problem resolved itself. No more failure indication when the car is started. It's almost as if the act of turning on the fog lights (the first time in years, literally) was sufficient to fix the issue. It couldn't be a some kind of corrosion issue on the bulb contacts that was burned away by the flowing current, could it?

 

Follow-up: Shortly after my last post the problem returned. Eventually I pulled the bulbs, cleaned the contacts with a pencil eraser (crude, but effective) lubed them with a little bulb grease and reinstalled. The problem has not returned for months.