Common DEF problem, how to clear SCR closed loop control at maximum limit fault code

How to clear the SCR closed loop at maximum limit SPN 520372 FMI 16 fault code. If this fault code is ignored long enough it will trigger
DEF inducement DEF lamp active SPN 521049 FMI 31
DEF inducement CEL lamp active SPN 521052 FMI 31
Then eventually the truck will derate.
To clear the fault codes, simply hitting the clear fault codes will NOT work. You have to check all the fault codes and fix them accordingly. Then you will need to check the following:
1. DEF quantity check
2. DEF ADS self check and look at the RPM speed
3. Check the delta pressure sensor, diesel doser injector and signs of blockage,
4. Perform a successful parked regen, if all goes well and passes
5. Perform an SCR efficiency test immediately after and monitor the LARMF compensation. The number must be at 0.91 or higher. This is pass or fail and must run completely without any interruptions.

[@johnenyinna1203]

The problem is not all mechanics know all these things you've explained. They end up creating more problems than solving

[@njaBriggs91]

Thats why you shouldnt let everyone do certain jobs

[@lucasreyes8883]

Muchas gracias Carlos sin duda tienes muy buena información que nos está ayudando a los que estamos empezando a conocer este tipo de situaciones gracias y los videos están excelentes siempre termino de mirar los completitos

[@JacobDybvig]

When i work on a frtlnr there are 2 things that need to be checked and cleaned every 6-12mo. Delta P ports for blockage, if blocked it will throw off the whole emissions system. 2nd the tube on the right side of 1-box, check to see if pipe is plugged or if the silicon hose is cracked. On a dd13 carefully unscrew the 7th injector and put a long screw driver in to clear soot build-up.

[@richardboffo]

this was a great video! I work on newer freightliners also and appreciate you breaking it down

[@douglaney1177]

Great job by Detroit to ensure we are spending plenty of time & $$$ in the shop.

[@CarlosDieselElectric]

Sad but true

[@SFMARK69]

@@CarlosDieselElectric I need help Carlos! I’ve been chasing these codes (SPN 520371, SPN 520372) on my 2019 Cascadia for months now! Freightliner changed my def pump, installed a new engine wire harness after saying something about a low voltage code that kept popping up and was kicking it out of regen. So almost $10,000 and 8 days later they give me my truck back saying it was fixed but a month later they came back!

[@SFMARK69]

@@CarlosDieselElectricthe second time they came back I had my EGR cooler replaced and had my engine cleaned out with this “diesel force” complete engine cleaning to clear out all the gunk throughout the engine, mechanic did scr efficiency test and it passed and I was sent on my way.

[@SFMARK69]

@@CarlosDieselElectriccodes came back a few weeks later and this time I bit the bullet and had my whole one box cleaned including dpf filters, I changed after treatment harness, and I replaced pretty much everything on the one box with the exception of the metering valve or def doser and the DOC temperature sensor.

[@思诚衷]

@@SFMARK69 Did you solve the problem？

[@bundylovess]

Awesome video mate thanks for sharing big thumbs up mate

[@OfficialSandfreak1]

My truck completely the regen successfully and right after the scr ran for about 2 hours and passed. No other codes active but Selective Catalyst Reduction Closed Loop Control at Maximum Limit is still active. Do I need to run the scr test multiple times? All numbers looked perfect during regen and scr. Thanks

[@CarlosDieselElectric]

@@OfficialSandfreak1 you may have to run it again. Any other codes?

[@DanielBlack-g8u]

So everything you showed us in the video . What’s the total about $ to get it done in your shop ?

[@ericmendez5815]

Bro! Put a donate button. All you owner ops need to support with MONEY. This info can save you youre business!

[@nodirjonzakirjonov3172]

or just post zelle acct info so we can send money for the time and knowledge you are sharing with us. thank you

[@GurdeepMarahar-j9p]

Hi on my 2018 freightliner cascadia I have a fault code 520372. We did all tests like nox sensor, def dozer,quantity test and scr efficiency .all good. But code shows up again after running around 200 miles. But now code is gone but engine light is still on. Please advise. Thanks

[@CarlosDieselElectric]

@@GurdeepMarahar-j9p what is the FMI code?

[@GurdeepMarahar-j9p]

@CarlosDieselElectric 16

[@CarlosDieselElectric]

@@GurdeepMarahar-j9p what was the NOx efficiency during the regen and SCR efficiency test?

[@noesnaula8863]

❤THNK YOU GRACIAS POR TU TIME KEEP UP ❤

[@nodirjonzakirjonov3172]

bro you are my problem solver.😊 thank you

[@DanielBlack-g8u]

How long can you keep driving with these codes ?

[@trex7944]

Thank you Pedro!

[@goodfella000001]

Pedro For a 2018 Freightliner Cascadia what is the typical scr inlet and outlet temperature range ..?

[@WanderingRobotStudio]

Subbed

[@timstanford3443]

What did you figure out with the drifting fault? The last one that was active?

[@johnavalos6010]

Pedro, good information. However, I'm experiencing scr efficiency test stops after 5 or so minutes of active test. I have to run MANY test to reach the maximum value before light goes off. Do you experience same as I do?

[@CarlosDieselElectric]

Yes, to reach the LARMF it can take an awhile. Is the truck surging when the fan clutch kicks in? In other words, then the fan clutch turns on at 220, do you see the EGR valve go to 100 and the psi jump around?

[@johnavalos6010]

@@CarlosDieselElectric I'll have to look at that next time. But haven't heard the truck surge when fan clutch kicks in..if that happens what does that mean. Also, I never thought to check doser valve. I'll check that next time a truck comes in for this issue. It's happening on dd5 and dd15. Thanks

[@seabourne17]

Hi,nice video,i got a same code scr closed loop,i did reign,no check engine light,but during scr test,check engine light came with same code,did def quantity test,125 ml,good quantity,def quality good of 32.5 urea,but not outlet is 89 ppm and above,what could be the issue,inlet box to scr is 520ppm approx,i want to know,why not outlet ppm not coming down

[@CarlosDieselElectric]

Look inside for any signs of soot. Could have a compromised One Box. Possibly a bad sensor. We have even put the outlet sensor on the outside to bring the efficiency up towards 100%.

[@mauricioquintanilla1802]

What r the step to do the SCR test I didn’t see the step where should I go routine check then where scr n press test or how should I do it thanks bro

[@CarlosDieselElectric]

Step 1, parked regen. If it completes and passes NOx efficiency Step 2, go to the SCR tab, bottom left choose the drop down menu for NOX efficiency test. This can run 1-3 hours depending on how low the LARMF is. This has to increase above .092 The higher the better. It will complete on its own even after reaching 0.92. Just let it do its thing.

[@fredybaron9117]

Este video lo tienes en español pedro?

[@moonbounce]

I wonder how people are going to get the things they need after all of this government crap finally kills the trucking industry for good? Truck used to be reliable, and are now just headaches (and wallet drainers) waiting to happen.

[@JasonCollette-eb8mw]

Can the def pump be rebuilt? I know about the filter and screens. but is there rebuild options?

[@CarlosDieselElectric]

Not sure if there are any rebuild options. I would go new. The part number usually starts with EA. They are more reliable. RA means rebuilt

[@serggla924]

My pump rpm jumping around very quickly from 1000,1200,1400,1200,1000,1400 ect Not staying as stable as yours. Failing pump? My codes went away during the scr efficiency test, nox efficiency good, ect

[@CarlosDieselElectric]

Start with a DEF quantity test and confirm the amount.

[@andrezgomez2492]

Where’s your shop located?

[@eduardocalderon7498]

Does the scr nox conversion efficiency low detection by moving avg go away when it passes?

[@CarlosDieselElectric]

You will have to look at other fault codes to better help you. Also, inspection the tail pipe for soot. Run a regen and see what the temperatures and pressures are. This will help. But if it successful is should clear.

[@gilsot123able]

Have tried 2 def pumps and ADS def pressure 2 is at 14.5 psi and ads pump speed is over 2000 please help thanks!

[@CarlosDieselElectric]

Check for restrictions in the DEF system. Speed should be 900-1300 RPM. What codes are you getting?

[@gilsot123able]

@@CarlosDieselElectric 520342 17 and ads def pressure came up to 145psi but problem is def pump is at 2200

[@gilsot123able]

@@CarlosDieselElectric any suggestions?

[@CarlosDieselElectric]

@@gilsot123able check for any DEF restrictions in the system. Have you done a quantity test? If you have , how much are you getting?

[@gilsot123able]

@@CarlosDieselElectriccleared out the lines by blowing air in them and don’t have the def quantity numbers but was done codes went away and only mil light is on showing the def pressure too high and pump is still at 2200

[@DanielBlack-g8u]

How long can you drive with this fault code ?

[@CarlosDieselElectric]

Depends, it will start to derate the speed to about 55-65 mph How long has the light been on ?

[@DanielBlack-g8u]

@@CarlosDieselElectric about 4 days . I just keep resetting it for now . Someone said scr efficiency test helps but then this code keeps coming back and apparently there’s no fix . Sound like programming issue. I need to get to your shop in couple weeks to do the maintenance and check on these codes

[@CarlosDieselElectric]

@@DanielBlack-g8u go into the aftermarket tab and reset or put New One Box. Someone told me that works. I haven’t been able to confirm but it’s worth a try.

[@DanielBlack-g8u]

@@CarlosDieselElectric for now I only have this OTR performance app that I use on the road . Not too many options on here . Will see how long I can drive before it puts me in derate. Currently I’m on East Coast Need to invest in better equipment

[@AmanAndHisTruck123]

Where’s your shop located at boss?

[@CarlosDieselElectric]

We are at 659 S Maple Ave a Montebello, Ca

[@guillermobelloso2312]

Do you do this CumminsISX15?

[@CarlosDieselElectric]

Cummins has a different process for clearing codes. What fault codes are you having?

[@guillermobelloso2312]

@CarlosDieselElectric don't have any codes but it seems that I'm going through a lot of diesel exhaust fluid. I burn around 7 gallons a week with around 110 gallons of diesel. I changed my DEF doser and it's the same.

[@CarlosDieselElectric]

@guillermobelloso2312 there should be procedure to check DEF quantity. Also, software, might need an update. Check your EGR system , SCR system might have an issue. How many miles are on the truck?

[@guillermobelloso2312]

@CarlosDieselElectric 475K do you do those tests

[@govinlama2731]

❤❤❤❤❤

[@hlrtrucking6011]

first off i think its absolute bullcrap to say it took five hours or so to complete this task. after measuring the def dos and changing off some gaskets, immediate test should commence, not for you to say you were messing around with it the day before. this was a good video but a true confession of over charging the customer. procedures are procedures. should be followed in steps 3 hours max is sufficient.

[@CarlosDieselElectric]

I don’t believe 3 hours is enough time to complete everything. If the customer arrives later in the afternoon I can only do a regen to check the numbers. The following morning, I can check the DEF system (quantity and pump). Then I have to do a regen again and then right after go into the efficiency test. So this test can definitely take some time. I wish it wouldn’t. Trust me. Working on these units unfortunately just takes time.

[@serggla924]

Dude open up an online mechanic school and make a course.

[@CarlosDieselElectric]

Great idea.

[@pauliesev6]

Dont waste your money chasing all these aftertreatment problems. Delete it and be done with it.

[@jshin10491]

You can’t register truck in California if you don’t do the smoke check. We all know it’s simple just delete the filter. So don’t be stupid to drive around without the filter. A lot of truck drivers will be quitting driving trucks it’s shame 😢

[@m80thebrawler1]

This is a response from a moron

[@MrChevrolet94]

Just delete it

[@PrabhjotSandhu-tm9yu]

Not worth it if you go to California and resale value also go down

[@MrChevrolet94]

@@PrabhjotSandhu-tm9yu I’m in Atlanta Georgia, thank you very much

[@nospam3001]

@@MrChevrolet94 Dealership shops won't touch it if you delete it. Why don't you just fix it? It's not magic.

[@CarlosDieselElectric]

Deleting is always an option but there are many factors to consider when deleting. Especially in California will start to smog trucks two times per year.

[@MrChevrolet94]

@@nospam3001 bro, have you seen how fucking expensive that shit is to fix???!!!!