No code for DEF?

 

That’s correct… only those EGT sensor codes.

I spoke to a couple diesel techs today and one just said, “sounds about right, the truck won’t be able to regulate the EGTs is the DEF system isn’t working properly.” Not exactly how I thought it worked but whatever.

I jumped in the truck this morning. For the first 5 mile drive, the message didn’t come on or subtract any miles. The next start up it came back on with 148 miles to go. I did another 60-70 miles today and it stayed on and counted down to 80 miles now.

I did some towing and a lot of highway driving and the temps seemed okay. Not sure what normal is anymore but none seemed way out of wack.

I was able to test the resistance at the back of the DEF injector plug and it was 14 ohms. 11-13 is ideal. Doesn’t seem catastrophic but I really thought that I’d been getting one of those “flow” CEL codes if it was the pump or injector. Any thoughts?

I really wanted to pull the injector off to clean it but the bolts are completely rusted. 🤯

 

@TCDiesel recommends adding distilled water to DEF. I believe he said you can mix 2 parts water to 1 part DEF for your year. It might help remove DEF crystals if that’s the issue. My year can do 2.5 gallons DEF to 1 gallon water which I’m trying and works fine.

 

Hope you are accepting guesses. I think one of the inputs to the algorithm that determines DEF dosing is EGT(not sure which one or ones). Guessing that if an EGT sensor is providing bad data that the computer doesn’t know how much DEF to dose and you get the warning.

In your original post, #4 does seem high but I don’t know if this was while you were running with everything stabilized, cooling down or whether or not you were in an active regen. I only look at #1 and #3 on my truck and they are usually close after everything is warmed up but diverge during cool down or active regen.

 

I'll definitely accept guesses...Thank you.

I should have elaborated on those original temps. That was while the truck was off and parked in the driveway about three hours after I got home so it had plenty of time to cool. I read another article about a guy seeing temp differences when the truck was off and cold and it helped troubleshoot the sensors.

As for temp sensors, I've read that there are five of them and I'm pretty sure that I've counted five of them under there. But my code reader shows the readings for sensors 1-4. Seems kind of weird.

 

How are you reading the codes?

 

Unfortunately the DEF tank is full now. I added another 2.5 gallons to fill it up with hopes that it'd help. The codes, that were very sporadic last month, went off for a few weeks when I added DEF last time.

As for reading the codes, I'm using a cheap reader from Amazon but it does a pretty good job. It also reads the live data streams. That's how I'm able to see the EGT temps. I also have AlfaOBD but I haven't tried it yet. I'm not sure that it would show anything different but I might try it later tonight.

P2482 is showing as the current code
P2482 & P2483 are showing as the permanent codes

 

Yeah I thought there were only four as well but looking around in the internet it looks like there are 5:

1. Post Turbo
2. Rear of DOC
3. Rear of DPF
4. Center SCR
5. Rear of SCR

WARNING that information is from unverified internet research. I think both of your codes are for #5. I think it’s plausible that the computer needs good info from #5 to dose DEF.

Also, maybe I’m confused or we are talking about two different things but all those EGT numbers are really high for 3 hours after shutdown. I don’t even shut my truck down until EGT #1 is 400 or less. Maybe a decimal point is missing or I’m just confused as usual. I would expect to see numbers near ambient 3 hours after shutdown.

 

Yeah I thought there were only four as well but looking around in the internet it looks like there are 5:

1. Post Turbo
2. Rear of DOC
3. Rear of DPF
4. Center SCR
5. Rear of SCR

WARNING that information is from unverified internet research. I think both of your codes are for #5. I think it’s plausible that the computer needs good info from #5 to dose DEF.

Also, maybe I’m confused or we are talking about two different things but all those EGT numbers are really high for 3 hours after shutdown. I don’t even shut my truck down until EGT #1 is 400 or less. Maybe a decimal point is missing or I’m just confused as usual. I would expect to see numbers near ambient 3 hours after shutdown.

I was definitely wrong In those temps from post #1. I just plugged in AlfaOBD and my laptop and drove around and the temps were way lower and right at what I see for normal EGTs. All below 500°.

I think my cheap scan tool uses voltage differential or something and I assume it was reading Fahrenheit. I feel pretty dumb. I’ll try to edit that post so it doesn’t mess with anyone else.

In regards to those EGT sensor locations … I’ve seen the same list online and it seems legit but AlfaOBD allowed me to monitor EGT sensors 1-8. Only 1-4 actually read and displayed anything so maybe there are only 4.

 

The two 'stored' codes are for temperature issue with the SCR. I believe that they get stored to create a permanent un-removable record of the incident (high temp).

I would remove the DEF injector very soon, clean & inspect both sides (don't forget a new gasket) and re-install. Test for DEF delivery before re-installing. You may also want to consider some kind of fuel additive designed to address the DPF performance.

I have heard of recc's to add distilled water to the DEF tank, I feel that's an attempt to clean out the DEF injector (and related components) and ultimately restore normal SCR functioning. I say remove it, clean it, test it & re-install. Yep, it's a PITA but it really doesn't take that long. Spray those bolts with some penetrant and crawl under there.

Good luck!

 

The two 'stored' codes are for temperature issue with the SCR. I believe that they get stored to create a permanent un-removable record of the incident (high temp).

I would remove the DEF injector very soon, clean & inspect both sides (don't forget a new gasket) and re-install. Test for DEF delivery before re-installing. You may also want to consider some kind of fuel additive designed to address the DPF performance.

I have heard of recc's to add distilled water to the DEF tank, I feel that's an attempt to clean out the DEF injector (and related components) and ultimately restore normal SCR functioning. I say remove it, clean it, test it & re-install. Yep, it's a PITA but it really doesn't take that long. Spray those bolts with some penetrant and crawl under there.

Good luck!

Thanks, that was the plan last night. I spent a solid hour under the truck working on those little 10mm bolts. They’re completely toast. Before I did anything I soaked them in PB Blaster and walked away for 15 minutes. I would say there is nearly zero rust under the truck expect for all of the exhaust fasteners. The heads on both of those injector bolts just crumbled to chunks from rubbing them with my fingers. I considered dropping the whole SCR canister muffler looking thing next just to get the DEF nozzle up on a work bench. Then I could cut the bolts, drill them out and get a couple new stainless ones.

I have 2 EGT sensors on order so we’ll see if they does anything.

 

If you are interested there is a YouTube video where the person removes a DEF injector from a SCR while off the truck. His video seems oriented at how to loosen/remove severely rusted bolts/nuts. I would have new nuts on-hand, ready to install, if I was going to attempt to remove them.

 

I believe that I saw it, or a video just like it the other day. The guy used a torch to heat it up and worked them loose pretty slowly. My bolts are completely trash though, they crumbled just from rubbing them with my finger and they don't even resemble the shape of a hexagon anymore. I tried to take some pics but they're way out of focus.

 

I'm still waiting on the new EGTs sensors to come and they should be here tomorrow. Today I had to drive the truck about 40 miles today to pick up my camper and I noticed something. The check engine light for P2482 came one right as I started the truck but the "5 MPH Max Speed in XXX mi Service DEF System See Dealer" message did not come on at all during the first 15 mile drive. BUT right when I parked the truck and started it again the message popped back up with 80 miles to go and stayed on (counting down) the rest of the day.

This is the same thing that happened when it first showed up on Tuesday and again Wednesday. Hopefully I'm making sense but the countdown message does seem to appear during the first drive cycle of the day but after you turn the truck off and restart it, it comes on.

I'd like to think that it has to do with the EGT sensors and hopefully they'll be the fix. Let me know if it sounds like another reason.

 

The codes you mentioned have to do with SCR temp (too high). The 'countdown message' is designed to induce owners to take their vehicles to a dealer (hence the see dealer message) so the SCR won't be damaged by a continuous out-of-normal condition. I feel that ensuring that DEF delivery is occurring properly is one step in getting past this situation. If you run your 'countdown' all the way down you risk engaging limp mode, which will require a dealer visit.

I encountered a 'see dealer' message due to a failed (electrically, not blockage-related) DEF injector. My injector was not fouled or crusty at all, but was 'dead' electrically. The replacement unit (from Geno's) came with an attached gasket and measured approx 20 ohms resistance when checked before installation. I know the norm for these is 11-13 ohms, I just figured that Stellantis raised the resistance to make the unit more failure resistant. My attachment nuts were rusty but good enough to re-use. The see dealer message eventually disappeared on it's own after a number of cold starts (don't actually remember how many starts, but more than I anticipated) which was a huge relief. My only concern now is that the message went away with around 20 miles left in the countdown; if it comes back for another failure, will it start at 150 miles or go back to 20??!!

AVOID LIMP MODE! Pull that DEF injector and clean it. If you have access to a NICE code reader get to work with it. Mine allows me to read the performance of individual sensors in the exhaust system (real time with engine running). Check the sensors you suspect of mis-performing before replacing them, unless you already know that they are faulty.

P2482 code showing at startup makes me think that it is showing immediately b/c it's now a stored code. The countdown message shows up later b/c the PCM needs to verify the problem, it may require two (2) successive faulty readings to confirm a problem and then display the message. That message ain't goin' anywhere until the issue that brings it on has been properly rectified. AND, your time to fix it is limited!

Having been subjected to a countdown message I can feel your pain; the anxiety brought on by that message was overwhelming! My incredible truck was seemingly brought to it's knees by a shorted electrical part. For me getting to a dealer is a real PITFA (must remove installed slide-in camper) and I was not overly confident in the dealership's abilities to properly diagnose & repair the issue. Through research I learned that if your truck arrives at the dealer in limp mode they will have to use a special 'tool' to reset the countdown message before flashing the PCM to remove codes, etc. It sounded like a nightmare to me so I was thrilled when my message finally went away on it's own, which I attributed to a correct repair and a proper number of cold starts w/o any errors detected.

Good luck! Sorry to bore you with my war stories

 

The codes you mentioned have to do with SCR temp (too high). The 'countdown message' is designed to induce owners to take their vehicles to a dealer (hence the see dealer message) so the SCR won't be damaged by a continuous out-of-normal condition. I feel that ensuring that DEF delivery is occurring properly is one step in getting past this situation. If you run your 'countdown' all the way down you risk engaging limp mode, which will require a dealer visit.

I encountered a 'see dealer' message due to a failed (electrically, not blockage-related) DEF injector. My injector was not fouled or crusty at all, but was 'dead' electrically. The replacement unit (from Geno's) came with an attached gasket and measured approx 20 ohms resistance when checked before installation. I know the norm for these is 11-13 ohms, I just figured that Stellantis raised the resistance to make the unit more failure resistant. My attachment nuts were rusty but good enough to re-use. The see dealer message eventually disappeared on it's own after a number of cold starts (don't actually remember how many starts, but more than I anticipated) which was a huge relief. My only concern now is that the message went away with around 20 miles left in the countdown; if it comes back for another failure, will it start at 150 miles or go back to 20??!!

AVOID LIMP MODE! Pull that DEF injector and clean it. If you have access to a NICE code reader get to work with it. Mine allows me to read the performance of individual sensors in the exhaust system (real time with engine running). Check the sensors you suspect of mis-performing before replacing them, unless you already know that they are faulty.

P2482 code showing at startup makes me think that it is showing immediately b/c it's now a stored code. The countdown message shows up later b/c the PCM needs to verify the problem, it may require two (2) successive faulty readings to confirm a problem and then display the message. That message ain't goin' anywhere until the issue that brings it on has been properly rectified. AND, your time to fix it is limited!

Having been subjected to a countdown message I can feel your pain; the anxiety brought on by that message was overwhelming! My incredible truck was seemingly brought to it's knees by a shorted electrical part. For me getting to a dealer is a real PITFA (must remove installed slide-in camper) and I was not overly confident in the dealership's abilities to properly diagnose & repair the issue. Through research I learned that if your truck arrives at the dealer in limp mode they will have to use a special 'tool' to reset the countdown message before flashing the PCM to remove codes, etc. It sounded like a nightmare to me so I was thrilled when my message finally went away on it's own, which I attributed to a correct repair and a proper number of cold starts w/o any errors detected.

Good luck! Sorry to bore you with my war stories

No problem, thanks for sharing. I re-re soaked the DEF injector bolts again this morning with intentions of dropping the SCR tonight or tomorrow.

I should have a new EGT sensor this evening so we do how it goes.

As for the dead injector… How’d you determine that it was dead?

 

No resistance across the terminals (measured after it was completely removed from the SCR & wire harness).

 

Looks like EGT sensor #5 was the only issue. After installing the new sensor the CEL and P2482 immediately went away. It took a few days and about 3-4 drive cycles to get P2483 to come off as a permanent code.

All of the time waiting on parts definitely let me worry about the actual DEF system when it was just the one sensor. I’d say that my biggest takeaway is that the system does consider the EGTs for dosing DEF.

Thanks for all of the input and assistance. Hope this could help someone else in the future.