I had this same problem with my 2004 Phaeton 35RH, Cummins 300 ISB, when I was in CO this past Sept/Oct. I had it thoughly checked before we left AL, it turned out to be a cracked coolant reservoir and thermostat (don't understand about this one though). Both lights (Checked Eng/Shutdown Eng) came on, put the engine into a 'limp mode', then less than a minute later lights when out. Got repaired in Loveland, CO at Stan's Auto Service, they were really good in getting me in and making the repairs.