DEF system performance in Sub-Zero temps

[mbarber84]

Would be awesome.



These engines already make really low NOx emissions, I’m not concerned in the least.




Next time my DEF freezes I’ll monitor EGR use.

What I can’t figure out is the variation between the level reading on the iDash and my actual instrument cluster. I’m guessing that the instrument cluster retained its last previous reading and didn’t “update” when I started the truck because the system recognized the fluid was frozen and wasn’t able to provide an updated reading?

 

[H3LZSN1P3R]

In theory, even if the tank was “Full” (at its rated capacity), it should have room to expand because the tank’s actual physical volume is larger than its rated capacity. That being said, it’s very difficult to know when it’s actually “full” when filling unless you’re very closely and slowly monitoring the gauge on the dash. Where a lot of people get into trouble is when they’re filling the tank from a bulk tank and pump. It’s easy to overfill it in that case. Ram actually put out a TSB on this several years ago because they were seeing so many cold weather performance issues with the system.
DEF freezing solid inside the filler neck from overfilling was one of the points. I have stuck with the 1/4 to 3/4 practice since the day I took delivery of both my 2017 and now this 2022 and it has never failed me yet.

The fill pipe is about 3/4 the way up the tank so in theory when “Full” there is an air gap at the top of the tank

 

[AH64ID]

In theory, even if the tank was “Full” (at its rated capacity), it should have room to expand because the tank’s actual physical volume is larger than its rated capacity. That being said, it’s very difficult to know when it’s actually “full” when filling unless you’re very closely and slowly monitoring the gauge on the dash. Where a lot of people get into trouble is when they’re filling the tank from a bulk tank and pump. It’s easy to overfill it in that case. Ram actually put out a TSB on this several years ago because they were seeing so many cold weather performance issues with the system.
DEF freezing solid inside the filler neck from overfilling was one of the points. I have stuck with the 1/4 to 3/4 practice since the day I took delivery of both my 2017 and now this 2022 and it has never failed me yet.

I always fill the tank and I’ve had it freeze nearly full too. But I fill with a pump and I think that’s why there is room. Filling with a box makes it easier to overfill. I don’t recall reading about issues from overfilling with a pump, just a box.

What I can’t figure out is the variation between the level reading on the iDash and my actual instrument cluster. I’m guessing that the instrument cluster retained its last previous reading and didn’t “update” when I started the truck because the system recognized the fluid was frozen and wasn’t able to provide an updated reading?

I think that’s a PID issue, some of them just don’t report accurately. The level sensor also isn’t a traditional float so that may play into it too.

 

[mbarber84]

I always fill the tank and I’ve had it freeze nearly full too. But I fill with a pump and I think that’s why there is room. Filling with a box makes it easier to overfill. I don’t recall reading about issues from overfilling with a pump, just a box.



I think that’s a PID issue, some of them just don’t report accurately. The level sensor also isn’t a traditional float so that may play into it too.

Sorry I should have clarified:

“Topping off” with the pump is what I intended. Trying to force more fluid in after the automatic shutoff engaged by retracting the nozzle and filling further.

I’ve had this one on file for a long time, and have skimmed it many times but missed the statement:

“Once ambient temperatures reach approximately 12°F (-11°C), the DEF fluid in the tank will freeze. The P203E diagnostic will not run if the DEF tank, and ambient temperatures stay below 39°F (4°C).”

P203E being “reductant level sensor circuit intermittent/erratic”

 

[Deleted member 47449]

"Extreme Cold" has no real definition. Varies by region. At least the DEF is stated to freeze at 12F. From the service repair statement it appears that 39F is the "warm" temperature, whereas, below 39F is the "Extreme Cold"?

 

[AH64ID]

"Extreme Cold" has no real definition. Varies by region. At least the DEF is stated to freeze at 12F. From the service repair statement it appears that 39F is the "warm" temperature, whereas, below 39F is the "Extreme Cold"?View attachment 81660

In terms of DEF extreme cold would be temps where DEF would freeze, so below 12°F.

 

[AH64ID]

Alright, little update to what I’ve noticed. Temps got to -27°F two nights ago and -35°F last night. Don’t think we got above the mid-teens yesterday and truck wasn’t really driven. Pretty sure the DEF, 3/8 full, was either frozen solid or really close to it this morning.

Went for a drive to to snowshoeing today and temps were between -9°F and 3°F in the drive. DEF showed 12° (lowest I’ve seen report even when the truck hasn’t seen a temp that warm in days previously so I think part of the new programming is to not measure temp that cold). DEF concentrate showed 0.0 and DEF level showed 0% all day.

On the drive home we stayed below 0° for twenty or so minutes and then went from 0°F to 10°F in a matter of miles and next thing I saw DEF was at 18°F and being injected normally. Concentrate and level were still at 0%.

Parked at the store for 5 minutes, the DEF went from 19°F to 16°F in that time with 13° ambient temp.

Last think I’ll add is the DPF was in an active regen when we parked for the snowshoe and the DPF was still over 800°F. I wonder if that got the thawing motion started, but no way to know since I haven’t seen anything reported below 12°F. It was -9°F out when we parked.

So, DEF will warm below 12°F but I’m still not sure at what temp that started. There was no indication it was happening below 0°F.

Really could use some more detailed info.

 

[mbarber84]

Alright, little update to what I’ve noticed. Temps got to -27°F two nights ago and -35°F last night. Don’t think we got above the mid-teens yesterday and truck wasn’t really driven. Pretty sure the DEF, 3/8 full, was either frozen solid or really close to it this morning.

Went for a drive to to snowshoeing today and temps were between -9°F and 3°F in the drive. DEF showed 12° (lowest I’ve seen report even when the truck hasn’t seen a temp that warm in days previously so I think part of the new programming is to not measure temp that cold). DEF concentrate showed 0.0 and DEF level showed 0% all day.

On the drive home we stayed below 0° for twenty or so minutes and then went from 0°F to 10°F in a matter of miles and next thing I saw DEF was at 18°F and being injected normally. Concentrate and level were still at 0%.

Parked at the store for 5 minutes, the DEF went from 19°F to 16°F in that time with 13° ambient temp.

Last think I’ll add is the DPF was in an active regen when we parked for the snowshoe and the DPF was still over 800°F. I wonder if that got the thawing motion started, but no way to know since I haven’t seen anything reported below 12°F. It was -9°F out when we parked.

So, DEF will warm below 12°F but I’m still not sure at what temp that started. There was no indication it was happening below 0°F.

Really could use some more detailed info.

Glad to hear this. At least it parallels what I was seeing the other day. Thanks for the detailed response as always. I agree with you, having documentation to read would be helpful, and it’s something I am trying to obtain.

 

[Deleted member 47449]

Got this concerned text message (below) this morning from our family regarding our 2014 Ram 2500 4x4 Cummins near West Yellowstone, Wyoming. I was about ready to drive there with our 2024 Ram 3500 4x4 Cummins to help get it going. It just needed a longer warm up due to the engine block heater wasn't plugged in. Neither a fuel or DEF issue. West Yellowstone was -29F overnight.

I would like to see Ram documentation on both the DEF heater and at what temperatures to use the Cummins engine block heater. When it gets below 5F I usually plug ours in beforehand, but I've started it without at lower temperatures.

 

[mbarber84]

Got this concerned text message (below) this morning from our family regarding our 2014 Ram 2500 4x4 Cummins near West Yellowstone, Wyoming. I was about ready to drive up there with our 2024 Ram 3500 4x4 Cummins to help get it going. It just needed a longer warm up due to the engine block heater wasn't plugged in. Neither a fuel or DEF issue. West Yellowstone was -29F overnight.

I would like to see Ram documentation on both the DEF heater and at what temperatures to use the Cummins engine block heater. When it gets below 5F I usually plug ours in beforehand, but I've started it without at lower temperatures.

View attachment 81783

Mine gets plugged in anytime the overnight temps drop below 50°F. The block heater is cheap to operate, and is an excellent way to help the engine get to operating temp faster. The faster you can get the engine to operating temp the better, especially on a hydraulic lifter engine. Warm oil is better than cold oil. Using the block heater overnight also eliminates the need for the truck to fire up the grid heater the next morning. Soaking the block in heat raises the IAT above 66°F and thus the grid heater won’t need to activate.

Both the 2018 and older, and 2019+ trucks will automatically idle up to help warm the engine faster. Only difference is, the 2019+ automatically adjust the VGT to help load the engine and produce heat faster. The 2018 and older you had to turn the exhaust brake switch on.

 

[H3LZSN1P3R]

Got this concerned text message (below) this morning from our family regarding our 2014 Ram 2500 4x4 Cummins near West Yellowstone, Wyoming. I was about ready to drive there with our 2024 Ram 3500 4x4 Cummins to help get it going. It just needed a longer warm up due to the engine block heater wasn't plugged in. Neither a fuel or DEF issue. West Yellowstone was -29F overnight.

I would like to see Ram documentation on both the DEF heater and at what temperatures to use the Cummins engine block heater. When it gets below 5F I usually plug ours in beforehand, but I've started it without at lower temperatures.

View attachment 81783

Thats fuel issue im sure as -29°F is not cold enough to cause any other issues with these trucks…

 

[mbarber84]

Thats fuel issue im sure as -29°F is not cold enough to cause any other issues with these trucks…

Yeah fuel gelling.
Have to let it idle and give the fuel heating elements in the filter housing a chance to warm the fuel up. Once some hot fuel gets circulating back to the tank it’ll get better.

 

[H3LZSN1P3R]

Mine gets plugged in anytime the overnight temps drop below 50°F. The block heater is cheap to operate, and is an excellent way to help the engine get to operating temp faster. The faster you can get the engine to operating temp the better, especially on a hydraulic lifter engine. Warm oil is better than cold oil. Using the block heater overnight also eliminates the need for the truck to fire up the grid heater the next morning. Soaking the block in heat raises the IAT above 66°F and thus the grid heater won’t need to activate.

Depends on the outside temps but my grid does kick on some days even when plugged in. I usually only plug in at -15°C which is your 5°F

 

[mbarber84]

Depends on the outside temps but my grid does kick on some days even when plugged in. I usually only plug in at -15°C which is your 5°F

Outside temp and amount of time it’s plugged in.
Like I said, mine get plugged in at 10pm and unplugged at 5am after it’s been started. We had some -8°F nights here last week and it was plugged in. No grid heater in the mornings. But we don’t see much past -10°F here and sub-zero days are few and far between. Normally it’s low double digits

 

[H3LZSN1P3R]

Outside temp and amount of time it’s plugged in.
Like I said, mine get plugged in at 10pm and unplugged at 5am after it’s been started. We had some -8°F nights here last week and it was plugged in. No grid heater in the mornings. But we don’t see much past -10°F here and sub-zero days are few and far between. Normally it’s low double digits

I am on a timer but block heater get to full temp in 3hrs before I leave for work but I am also surrounded by feilds so the wind can be quite strong which makes the IAT drop

 

[AH64ID]

Got this concerned text message (below) this morning from our family regarding our 2014 Ram 2500 4x4 Cummins near West Yellowstone, Wyoming. I was about ready to drive there with our 2024 Ram 3500 4x4 Cummins to help get it going. It just needed a longer warm up due to the engine block heater wasn't plugged in. Neither a fuel or DEF issue. West Yellowstone was -29F overnight.

I would like to see Ram documentation on both the DEF heater and at what temperatures to use the Cummins engine block heater. When it gets below 5F I usually plug ours in beforehand, but I've started it without at lower temperatures.

View attachment 81783

Sounds like a fuel issue, definitely not a DEF issue as DEF won’t immobilize a truck without a warning.

From the owners manual on the block heater. Nothing in there about the DEF heater because it’s passive to the operator when it freezes.



It was colder than -29°F in West Yellowstone last night, we saw -35°F.

I’ve started multiple times without a block heater below -20°F, even once without a grid heater, but they aren’t super happy.

Depends on the outside temps but my grid does kick on some days even when plugged in. I usually only plug in at -15°C which is your 5°F

When I DD’d my truck it was plugged in every night on a timer for 90 minutes (which I found got temps to 90% of being plugged in overnight). Generally the grids never fired.

I found a huge difference with a winter front installed vs not having one installed.

I was plugged in overnight the last two nights at -27°F and -35°F and had a WTS both mornings. No wind, but also no winter front. ECT was low 60’s after starting.

 

[Deleted member 47449]

We don't own a 2015 Nissan diesel (Cummins), but a 2024 Ram 3500 Cummins and a 2014 Ram 2500 Cummins. In any case DEF is DEF between all truck brands with it freezing at 12F. The heating state of it and the thaw time may be similar too this Nissan technical data.

Engine Locators

 

[AH64ID]

Some more observations today.

18°F seems to be an important temperature.

Only got to -20°F last night, but the trans was at 0°F so the DEF was likely colder since the trans was at operating temp when shutdown and the DEF was only at 18°F.

Started driving at around 5°F, but quickly went subzero again for a while. DEF showed 12°F at startup, still the lowest I’ve seen, but within 15 minutes was showing 14°F. At 25 minutes it was at 16°F and then at 35 minutes it was at 18°F. Up until this point the DEF pressure was 1.7psi, which is as low as I ever see it. The DEF commanded % would vary between 0 and 100%, which I think is trying to purge the frozen line. At 36 minutes the pressure rose to the normal injection pressure of 12.2 psi. The commanded % briefly, very very briefly, rose to 98% and dropped to 4% which it held for a few minutes and then it went to normal operation. The ambient temp at this point was around 10°F.

After 20 or so minutes the ambient temp rose to 21°F and DEF operation was normal, until the ambient temp dropped back to 10°F. DEF commanded % dropped to 4% and held it for a while. Eventually I saw the DEF tank rise a few degrees and injection started again.

Later in the drive the ambient temp rose above 18°F again and then fell back below it, which caused a repeat of the 4% commanded injection rate. Both times had a different length of time from 4% to normal injection rate, so I’m not sure what the ECM is looking for to resume normal injection.

So it seems that when the DEF tank is frozen the DEF temp required to begin injection is 18°F. I still am not positive when it begins heating the tank, though it doesn’t seem to always be heating. Maybe it’s above 0°F or maybe it’s always and it’s just really really slow?? Above 18°F ambient the DEF heater definitely doesn’t appear to be heating, but once the ambient temp drops below 18°F it’s working regardless of DEF temp.

All in all 18°F was a pretty important temp for both ambient and DEF.

 

[superjoe83]

Some more observations today.

18°F seems to be an important temperature.

Only got to -20°F last night, but the trans was at °F so the DEF was likely colder since the trans was at operating temp when shutdown and the DEF was only at 18°F.

Started driving at around 5°F, but quickly went subzero again for a while. DEF showed 12°F at startup, still the lowest I’ve seen, but within 15 minutes was showing 14°F. At 25 minutes it was at 16°F and then at 35 minutes it was at 18°F. Up until this point the DEF pressure was 1.7psi, which is as low as I ever see it. The DEF commanded % would vary between 0 and 100%, which I think is trying to purge the frozen line. At 36 minutes the pressure rose to the normal injection pressure of 12.2 psi. The commanded % briefly, very very briefly, rose to 98% and dropped to 4% which it held for a few minutes and then it went to normal operation. The ambient temp at this point was around 10°F.

After 20 or so minutes the ambient temp rose to 21°F and DEF operation was normal, until the ambient temp dropped back to 10°F. DEF commanded % dropped to 4% and held it for a while. Eventually I saw the DEF tank rise a few degrees and injection started again.

Later in the drive the ambient temp rose above 18°F again and then fell back below it, which caused a repeat of the 4% commanded injection rate. Both times had a different length of time from 4% to normal injection rate, so I’m not sure what the ECM is looking for to resume normal injection.

So it seems that when the DEF tank is frozen the DEF temp required to begin injection is 18°F. I still am not positive when it begins heating the tank, though it doesn’t seem to always be heating. Maybe it’s above 0°F or maybe it’s always and it’s just really really slow?? Above 18°F ambient the DEF heater definitely doesn’t appear to be heating, but once the ambient temp drops below 18°F it’s working regardless of DEF temp.

All in all 18°F was a pretty important temp for both ambient and DEF.

I haven't checked on my truck to see if they are functional, but Jscan shows various DEF heater pids in the data list for the PCM. If you have jscan it could be helpful to see when the heaters are actually commanded on. I don't think it's going to be cold enough here to check the function on mine to gather some data

 

[AH64ID]

I haven't checked on my truck to see if they are functional, but Jscan shows various DEF heater pids in the data list for the PCM. If you have jscan it could be helpful to see when the heaters are actually commanded on. I don't think it's going to be cold enough here to check the function on mine

I do have JScan so I’ll check it out. Not sure if I’ll be be below 0°F again anytime soon, but 18°F isn’t uncommon.