2014 2500 no mods, 37000 miles. We are from OK and just got to Orlando, FL when the code appeared on my CTS.

Fuel mileage has been dropping but has leveled out. We are pulling a trailer and have been on road since 11 this morning.

Thoughts on how to proceed, how long can I go with code, etc....

Hoping to not ruin a vacation.

 

P20EE - SCR NOx Catalyst Efficiency Below Threshold Bank 1

Looks like all kinds of possibilities from degraded DEF ( who knew it can last as short as a few months in hot weather????? ) to Catalyst problem, to DEF Injector problem, to a possible reflash to eliminate wonky computer saying things are out of whack.

I didn't see anyone with anything really bad happen though.......

 

I would recommend finding a 24 hour Cummins Certified Truckshop that can run some diagnostics on your engine to isolate the problem. As Pat said, it could be a number of things with that code.

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John_P

 

Thanks guys. I am finally at our hotel so do some more investigation now. Just hate being so far from home and having issues. I will find a local shop down here. Stupid Def, should have just deleted it last month when I was kicking it around but didn't want to have problems while we were on our trip. Go figure.

 

PCM may need to be updated, if code returns after flash update then possible issue with SCR or DEF deposits on DEF injector and in tube.

 

Thanks guys. Going to dealership to have flash done.

Guess we can move this one out of the Help section.

 

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Glad you made out alright Randy.

I will move your thread into the regular forum area.

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John_P

 

I have a 2013 with 70000 and have had to have the exhaust filter replaced twice now and who knows how many reflashes.