How to Troubleshoot DD15 DTC 4374 FMI 0 Under Pressurized Def System

[@grantbenjamin3981]

fkin awesome, please more ways to troubleshoot issues by charting the systems/issues that can be charted, in any software, thank you again

[@zerotimetrucks2253]

Most definitely will, I can put a dd15 video together. I have the info but I didn’t get a video while working on it but if you work on dd15 it could help. It was a high pressure fuel pump issue along with a bad delete and no engine codes. If your interested let me know and I’ll work on it

[@Daesha2u]

Awesome video. Thank you for helping me understand.

[@zerotimetrucks2253]

Thank you, happy it helped

[@Boyleheights213por-vida]

Thank you brother good video ...I appreciate your time and video I am now following.....keep making videos for us little guys...ty🙏🙏🙏

[@ejazahmed1947]

So accurate explanation for laymen to diagnostic scr

[@zerotimetrucks2253]

Great thank you

[@ericsanchez4641]

Thank you so much for sharing valuable knowledge, having the software makes a huge difference. Personal it worth spending the money on software if you own a dd13-16 . I’m still learning how to use the software there is so much information within.

[@zerotimetrucks2253]

Thanks for watching! We're glad you found the video helpful. We hope to have more DD content out for you soon. if you haven't already, subscribe so you don't miss it

[@keithneal1696]

Excellent instruction

[@zerotimetrucks2253]

Thank you much

[@georgeriley8024]

If it has an external leak that it's obvious why you don't have pressure. Just asking why you did not perform an scr ads self test first before you kick into an scr efficiency test? That will activate the def pump before you do an scr efficiency test

[@zerotimetrucks2253]

Yes you are correct and that should of been done . I was more about trying to diag the low pressure. This one was external and easy but when it’s internal such as a bad pump, bad pressure sensor, restriction etc. it’s not so easy. I was trying to show the use of the data log to help. Normally I use an oscilloscope to aid in the diagnostic. This software has a built in one that could be used. It’s not the best but It does work. Hope to get one in that’s a little more complicated so that I could possibly show the use of the oscilloscope. Thank you for your comment as it will help other technicians in their diagnostics and that is what I would hope to pass on.

[@georgetye4424]

Hello sir I appreciate the knowledge that you shared with this video. It definitely helps us shade treee mechanics understand a little better with what you taught us. I have these same codes on my Freightliner and noticed some Def residue on my def pump but I’m not sure if it’s bad or not? 5346 fmi 15, 4374 fmi 0, 3223 fmi 7 can you take a sec to help me out please? Ty for any info you can provide. Have a blessed day

[@zerotimetrucks2253]

Thank you for your comment , I don’t know what software you are using to check for diagnostic codes. I would check the 3223 code. I would check power and ground to the inlet nox sensor, back probing would be best to make sure you have battery voltage to the sensor. The way I do it is to back probe the ground and battery supply and check for battery voltage 12.6v. If I see let’s say 11v then I have a voltage drop which means I have a bad, dirty connection. If it is good battery voltage most probably the sensor is bad. And check the fuse for it. Correcting this code most probably correct the 5346 code. If not we need to check the def fluid for correct percentage 32.5% within in 5% should be ok. For def quality. 4374 pump speed, if you see a def leak external at the pump most probably the pump is bad but one way to test is to make a gauge you could install at the doser to see what the actual pressure the pump is putting out versus what you are seeing on the laptop. If the pump pressure that you see on your gauge is different from what your seeing on your laptop the the pressure sensor which is internal is bad and the pump needs replacement. Monitor your pump pressure , pump speed and duty cycle on your graph to hep you determine if your pump is bad, remember pressure has to go somewhere and we are trying to find where it’s going using the graphing chart. Either the pump just can’t build the pressure or we have a leak. We’ll see it on the graph. Does it build quickly when the pump is on and drops quickly when the pump is off? (Duty cycle is on and off) then we have a leak. If it is slow to build but holds even though it’s low when the pump is off then we have a weak pump . If it’s slow to build but gets close to the commanded pressure and holds then it’s a possibility that the filter is plugged. I hope that helps a little bit or at least give you a little bit more insight. Feel free to ask more questions , I’ll do my best to keep up with you. Again thank you , have a blessed and be safe day

[@515051506969]

Take off dozer clean really good and re gen truck good to go

[@zerotimetrucks2253]

Not sure what happened but I hope you got it figured out, any questions let me know I’ll try and help

[@515051506969]

@@zerotimetrucks2253 thank you

[@coler2040]

What if you have a Brand New Pump that runs continuous on the pump prime test but the pressure does not go over 15 psi.? I don’t have the diagnostic link. I have a more generic program called ETechnician. No visible crystallization or leaks. Vent line on the DEF tank is good. Not sure where to go next possibly the death header?

[@zerotimetrucks2253]

Hello, I am assuming you have the same def system that is in my video. It’s very possible that the def dosing unit is the problem. The pressure sensor is housed within this unit. The jumper harness to the def doser could be bad or the def doser could be bad. I would inspect the harness for wear. Inspect the connector for dirty pins or loose pins. I’m not familiar with your scan tool but it’s possible that you could connect your scan tool and disconnect the connector at the def doser. If you see code changes on your scan tool then I would assume the harness is ok. If so I would replace the def doser.

[@coler2040]

@@zerotimetrucks2253 thank you sir! Also your video is very helpful

[@zerotimetrucks2253]

@@coler2040 yes sir anytime, hope that helped you a bit. Don’t hesitate to get with me if you need anything. Thank you

[@TaskForce860]

Where can I get this computer, I got issues this issue and costed me a lot I just got it and can’t go over 5 MPH ? I do have the OTR device for regular regeneration but I need to do SCR regeneration I replaced DPF, DEF pump and filter but still get this issue again after a week drive 😢

[@zerotimetrucks2253]

Sorry to hear that, DDDL8 you can find it on the internet pretty easily.

[@omarahmed-ibrahim7883]

I have problem with this code can you help me please check engine light on all so def level on and plinking eec spn 520342 fmi 17

[@702trucker]

Where are you located? I need my system checked out!

[@zerotimetrucks2253]

We’re located at 4264 Fm 395 crystal city Tx. Shop # 8303744422

[@Travel-with-Elbek]

Can I drive 45 mile again in this situation?

[@zerotimetrucks2253]

I didn’t fully understand. Do you need to drive 45 miles to get somewhere? Or the truck only runs 45mph. If your not derated to 5mph yet, you can drive somewhere. Once you park and set your tractor brake you will be derated. If you are hooked to a trailer set your trailer brake NOT the tractor brake that will keep you out of 5mph derate. You will be derated in horsepower and maybe even down to 55mph but you could still drive to get somewhere.

[@woods457]

I have this fault code being triggered on a Stage 5 Mercedes/MTU OM470 engine, i'm not sure what the Detroit Diesel equivalent is but i think its the DD13.. In my case i didn't have any external leaks, the DEF tank and sender unit were clear and the pipes from the sender to the pump and then the injector and back are clear.. I have Mercedes "Xentry" software but it won't run the quantity metering test or the system leak tests, the MTU dealer is telling me that even though their present in the software they don't work on Stage 5 engines (does anyone know if that's true???).... OK so i ended up installing the pump, i tried to run the "Initial pump start up" procedure but that failed to initial, because the code kept coming back i relented and installed the injector, on installing i ran the "Learning" test for the injector which it did pass.. However the code still keeps coming back, i had the MTU dealer attend and they encountered all the same problems i did... Does anyone out there have any thoughts as to what it could be ????

[@zerotimetrucks2253]

Hello, I’ll be quite honest and say I have not worked on this type before. If you can get me the code and description of the fault I may be able to help you in the diagnoses. I’ll admit that it may be a slow process because I am blind to the system configuration and the software your using, but with that being said at the end of the day the theory of operation is the same.

[@woods457]

@@zerotimetrucks2253 Hi, Thanks for taking the time to reply...Fortunately not long after i posted my comment i was able to resolve the problem, it transpired that the feed pipe on the DEF sender unit in the tank was drawing air which in turn was causing the pump speed to be too high, and a lack of DEF pressure when the demand was needed...Once again thanks for offering to help...

[@zerotimetrucks2253]

@@woods457 That is great, happy to hear you got it going. That does make perfect sense as to why the pump speed would be high…

[@mimoreliamichoacan9422]

Can I run my truck with this code 4374?

[@zerotimetrucks2253]

Unfortunately It will engine derate 25% and it will derate more due to other regen issues caused by this code.

[@mimoreliamichoacan9422]

@Zero Time Trucks so is an emergency or can I drive it to my mechanic 300 miles away

[@zerotimetrucks2253]

@@mimoreliamichoacan9422 I am assuming the truck is running well enough to attempt to drive it. If so you can drive it to your mechanic. Hopefully you have a trailer. The truck will not derate more until you stop and set your tractor brakes. Once you set the tractor brakes the truck can go into more derate as far as speed goes. If have a trailer and you stop such as to get fuel do not set the tractor brakes only set the trailer brakes and you will make it to your destination. Once you set the tractor brakes the truck assumes your in a safe area and now it can derate. It will not do it while driving because it could cause an accident. Hopefully I got my point across.

[@kamizee7]

Did you make it 300 miles? ​@@mimoreliamichoacan9422

[@fishinwithcee3294]

I have that code but with fmi 6 high current

[@zerotimetrucks2253]

This is an electrical problem, open in a wire. I would check power and grounds to the pump and depending on the unit you have the injector metering valve or doser unit located at the on the back side of the one box. The injector metering valve has a pressure sensor you could test. The newer trucks have a doser unit (box) the pressure sensor is located inside of that box and it is not serviceable. You would need to replace the doser unit

[@fishinwithcee3294]

@@zerotimetrucks2253 thanks but it turns out it was code 4375 not 4374

[@zerotimetrucks2253]

@@fishinwithcee3294 Ok, that is most probable the pump. The pump has a short but check the power to the pump make sure the problem is not in the harness

[@fishinwithcee3294]

@@zerotimetrucks2253 another shop changed the harness I just do service at a farm shop but that was my itch to change it has the original pump since 2012 I checked air pressure and the truck did loose 25 % derate all wires look good it has all new heater lines so I’ve come down to the conclusion of def pump and thanks again for you time and info you got a new subsciber 👍🏽

[@triciapattiram6042]

Clean your one box there is a way of cleaning it.

[@zerotimetrucks2253]

We did get with the customer on that and made the repair.

[@derrickkilpatrick9244]

can anyone buy the software?

[@zerotimetrucks2253]

Yes anyone can buy this software. You can look it up on line. It is a little pricey though for the pro. It will allow you to program ECM and other modules. If don’t know how to do that then I wouldn’t purchase it. The standard version will allow you to do most everything other then programming. Hope that helps.

[@traviscole7069]

​@@zerotimetrucks2253 could you tell me the name of the software ( standard one) and what adopter to use to hook it up to the truck? Thanks

[@zerotimetrucks2253]

@@traviscole7069 yes it’s diagnostic link 8

[@traviscole7069]

@@zerotimetrucks2253 thanks for replying, I'm having same issue and broke on the road. Do you know what adopter connects the laptop to the truck? Sorry for asking again.

[@zerotimetrucks2253]

@@traviscole7069 I used nexiq 1 or nexiq 2, i preferably use the usb . I don’t like the wireless

[@515051506969]

Well I was wrong

[@zerotimetrucks2253]

That's ok! It's part of the process. We're glad you're on the right track. Thanks for watching!

[@fozman845]

Doesnt help any driver on the road unless you have the computer. So wtf

[@zerotimetrucks2253]

On this one a simple check would of been enough, repair the leak and you would probably be good to go. Unfortunately yes at times you will need a laptop to help you figure out where the problem or problems are at. I hope what you may have taken from this video is information. Information is a powerful tool. If your a DIY kind of person trying to make your own repair then this video would of helped you go through the process if your looking to outsource your repair well then you have some knowledge that will allow you to ask questions so that hopefully you find the right tech for the job.

[@fozman845]

@@zerotimetrucks2253 what are you talking about. You want subs truckers want "out of the box ideas". That means tricks of the trade. Videos of common problems can save a driver time and money. Ask yourself I am a driver in the middle of nowhere what can I do to fix this problem with no tools or experience to get me back on the road. MacGyver the sht out of it.