SPN 3363 FMI 18 DEF Heater High Temp Code

[tngengineer]

Hello,

Two years ago I got a DEF heater low temp code (not the code in the Title) in colder weather. Freightliner told me not to worry about it as I was headed south to Gaffney at the time. It cleared on the way and Gaffney could not find any issue. Then last fall got the same code in New England in October and took it to Freightliner in New Hampshire. $1000 later (did not touch the DEF heater itself) in replaced emissions parts, no further codes, but also no further cold weather driving - it went into winter heated storage.

I got the Title code in SD in September, called Freightliner 24/7 and they told me it was DEF heater high temp. It cleared itself, then next day came on again and cleared again. Third time it came on it stayed on.

After getting the high temp code for the third time in SD, I used a C-clamp to pinch off the engine coolant flow to the DEF heater in an effort to determine whether it was the temperature sensor or the coolant solenoid valve (stuck open). The code has not cleared since.

I had been led to believe the code is not a big deal for the engine so I decided to wait until I got somewhere where I would have a few weeks to get it looked at. I am now in TX in one place for a few weeks and will have Cummins look at it, being an emission issue (a Cummins issue) and because Freightliner hasn't had success.

Anyone else had similar codes and if so, how was it resolved?

[BMGM37]

This is the same code that I was getting on my Freightliner S2 chassis used on my Seneca Super C. Mine also went away the first 2 times after 3 key cycles but many were seeing this code and having the DEF Header replaced only to have the same problem pop up again. I contacted FCC and started questioning this and finally they said if you have had a 3363 code that the DEF Header sensors could have been damaged and the Header should be replaced. I also found out that the cause of all of this is that the coolant lines for the DEF heater were being installed in reverse at the factory and this would cause the DEF tank temp to get over 160 degrees which starts damaging the sensors. I was sent drawing of the coolant line routing and I checked mine and sure enough, they were reversed so I took mine in and got it replaced and FCC told the service center to check the coolant line but they said they were fine......checked them again when I got home and they were still wrong so I swapped them myself. I am always poking around on the DTNAconnect site and came across this bulletin, I am not sure what chassis is under you coach so you might see if it is listed on this Bulletin.