Ok guys I no nothing bout a cummins. Never had one before. And I hate it. Lol I'm a firm believer a Pete ain't a Pete unless its got a CAT in it. Would be like buying a classic 69 camero and you open the hood and there's a lil pissy sm block 289 ford in it. What a disappointment. Lol anyway bk to my question. This thing just randomly throws a ck engine light and derates the engine. No codes. And if you just hit the dyno switch it resets. Bk to normal till next time. Any ideas??