Is your BMW Engine Computer Suffering From Water Damage?

Pre-’96 vehicles can suffer from water damage to the ECU (engine computer) when taken through a car wash.  They have a single water drain on the passenger’s side that drains water from the windshield area. It has a short rubber tube leading down behind the engine.  Over time, the tube becomes brittle, and can become plugged with debris (tree leaves, etc.).  An automated car wash pours water onto the windshield faster than the plugged drain can handle and some of the overflow runs into the compartment where the ECU lives.  
 
The symptom is failure to start after passing through the car wash.  Repeated attempts to start it may damage the computer’s components.  Sometimes, the ECU can be saved by removal rom the vehicle, removing the cover and blowing it dry.