2009 6.6 HD losing power while towing

[jmill91]

When towing truck goes into limp mode.  This usually happens when pulling hills with 1/2 tank of fuel or less.  I can pull over and the engine is back to normal in approx. 10 minutes.  Check engine light comes on however clears itself within a day.  I have already replaced filter with a dual filter and direct flow pump.  Truck has approx. 108000 miles.  Any suggestions?

[Jglew82]

Hard to say given the info, but it sounds like it may be an emissions component or high EGT's. Have you had the codes scanned? You should still be able to pull history DTC's even though the check engine light isn't currently lit.