The Check Engine Light may come on with codes in engine computer memory for P0401, P0402, P0404, and P1335. In addition white or black smoke will be emitted from the tailpipe and the engine will feel down on power. This is most commonly caused by build up of black sludge and other solid deposits in the Exhaust Gas Recirculation (EGR) System (EGR Valve, EGR Cooler, Exhaust Back Pressure (EBP) Sensor, and EBP tube), intake manifold, turbocharger and the EGR throttle plate. Regularly adding a cetane booster to the fuel will aid in a more complete combustion and the engine oil should be replaced at the proper intervals to avoid sludge build up. Installing an EGR baffle kit also helps to prevent future EGR valve contamination.