Service DEF System message - See Dealer - P1C54 code

[PaulHubbard]

I had 1/2 tank of DEF, added 2.5 gallons of Walmart DEF (used it before without issues), but after 100 miles I got the DEF System message and said it would be reduced to 5MPH in 150 miles. The next moring there was no more DEF System messages but the Check Engine light remained. The code was P1C54, 'bad NOX sensor' (or something like that?).. I cleared the code and have not had any further issues. But I'm concerned since we're towing a 34' travel trailer and don't want to get stranded. Could a 'touch' of bad DEF from Walmart be the culprit?

 

[2003F350]

Difficult to say without diagnostics. NOx sensor could be on its way out. Could be you had some older DEF that was starting to go bad. Could be your DEF injector clogging possibly.

In my experience towing either highlights emissions issues, OR cleans your emissions out quite a bit. It can highlight emissions issues because your engine is working harder, and something that normally isn't a problem shows up. OR things are starting to build up in your emissions systems, and working the engine harder/hotter tends to burn these build-ups off.

 

[nlambert182]

Agree with the above. It's difficult to tell what the culprit is at this point.

However, if it's the NOx sensor(s), you have to replace both nox sensors and modules as a set. They are calibrated to each other and are not interchangeable. There's one on the turbo downpipe (module is on the hot side of the engine block) and another behind the SCR catalyst with the module mounted to the passenger frame rail.

That code means a few things:
Degraded or diluted DEF
clogged DEF injector
malfunctioning DEF dosing system (could be either pump or injector)
Malfunctioning SCR catalyst

It might not hurt to remove the DEF injector and inspect it for crystalization to see if it is clogged. If the DEF that is/was currently in the tank has been in there for >6 mos or so, there's a good chance it has started to go bad. You may get away with cleaning the injector. I'd start there anyhow. It's free to do.

You may also want to remove the DEF pump from the bottom of the tank and clean the tank really well. You can disconnect the fittings to the tank and insert a small pump with some hose to get as much out as possible. Then refill with DEF that has a fresher date (or... get some from a big truck stop... theirs is typically always pretty fresh).

 

[PaulHubbard]

Agree with the above. It's difficult to tell what the culprit is at this point.

However, if it's the NOx sensor(s), you have to replace both nox sensors and modules as a set. They are calibrated to each other and are not interchangeable. There's one on the turbo downpipe (module is on the hot side of the engine block) and another behind the SCR catalyst with the module mounted to the passenger frame rail.

That code means a few things:
Degraded or diluted DEF
clogged DEF injector
malfunctioning DEF dosing system (could be either pump or injector)
Malfunctioning SCR catalyst

It might not hurt to remove the DEF injector and inspect it for crystalization to see if it is clogged. If the DEF that is/was currently in the tank has been in there for >6 mos or so, there's a good chance it has started to go bad. You may get away with cleaning the injector. I'd start there anyhow. It's free to do.

You may also want to remove the DEF pump from the bottom of the tank and clean the tank really well. You can disconnect the fittings to the tank and insert a small pump with some hose to get as much out as possible. Then refill with DEF that has a fresher date (or... get some from a big truck stop... theirs is typically always pretty fresh).

Thanks for the info... So far (500+miles) and the Check Engine light has not returned, nor any messages. Hopefully it's all good.

 

[Gary276]

2019 Ram 2500, 73k miles. Last Tuesday July 1st, I got the Sevice DEF - See Dealer message with associated check engine light. I did some research and found out if you had the VB6 recall done the emissions system is covered by a warranty. Took the truck to the nearest Ram dealer. He said $209 for a diagnostic, I agreed to the diagnostic but told him not to proceed further without calling me first. I even left him a copy of the VB6 recall warranty paperwork. He called and said I needed a new injector and the total was just over $1000. I reminded him of the warranty and he said "oh yeah" and put me on hold. A few minutes later came back and confirmed the warranty covered the diagnostic and repair. Cost me $0. The point is, if I hadn't found out about the VB6 recall and mentioned it to the dealer I would be out $1000.