I tell everyone thaat runs a 2007 -up Cummins to "use it or lose it". Even if you are not towing just exercise the exhaust brake frequently. It helps to keep the soot build up from getting it sticky or flat out stuck. Once it doesn't work anymore you'll have to go into the dealer and have them clean it out (I'm sure costing $100s). Besides it sounds cool to use and helps on the brakes lasting longer anyway!