I had a similar problem with my E420 and it turned out to be the blue two prong temp switch part number
008-542-45-17

RKreutzer,
Were the fans running on high speed and was the A/C switched off? If so you have the same problem.
It is not normal operation.

Replacing the switch is a 5 min job.

See this thread: http://www.peachparts.com/shopforum/showthread.php?threadid=7301

Chris