My 2006 mini cooper goes haywire when it rains or goes through a carwash. I washed it 10 days ago and as I sat in the wash the service engine light and several other dashboard lights cam on. The Mini drove as if all the sensors in the engine were malfunctioning; rough, jerked, went in and out of gears. Once dry, the car is fine. It happened a second time when it sat in the rain. As soon as I started it, the same thing. I didn't move it. It dried and is OK. Any ideas on what to look for????

 

Water leak on the passenger side in front of the door. That's where the BCM lives. Could be a windshield, or if you have a sunroof, the drain tube. I'd get on it ASAP, electronics don't like water.

 

The problem was the ABS system. We isolated the problem to the passenger front side with a garden hose. Looked at the BCM but it was dry. Disconnected and cleaned all the ABS connections and the problem has disappeared.