... thank you

Terry Halder typically air comes out when the key is off. This is to purge the system of DEF, this is very normal. Now air should be present when you are doing a regen. You will need the software to perform a check of the system. I usually replace both the DEF metering unit and the PLM when I have this fault code. What other codes are present?

@@CarlosDieselElectric that is the only code present.

Air dryer, the air dryer cartridge will be the likely first thing to change. The air dryer should catch all the contaminates like water and oil. Also, if the air compressor is letting oil through . But first check the air dryer cartridge.

Thank you for the help, I am going to order a cartridge today.

Check the metering unit on the side of the One Box. The sensor or sensors might be bad. They tend to go out also.

@@CarlosDieselElectric ok cool thanks for replying

@Pedro Fuentes ok so I did a successful regen and the engine lights have not turned back on, but now I've noticed that I'm consuming very little def. I filled up Sunday night and it still shows full. I run as a team so the truck runs day and night.

You can run a DEF quantity test. The amount during the procedure should be around 135 ml.

@Pedro Fuentes ok ill try that. if that is my issue shouldn't I have my engine light on and an active fault code?

What have you done so far to clear the code?

Thank you. I purchased my software from DiagnosticLink.Nexiq.com

@@CarlosDieselElectric What if it's not your pressure limiting valve ,could it be wiring issue ,what did you do to diagnose it

@@nukenridge4921 Depends on what fault code or codes you are getting.

I have tried to complete or start a parked regen? What are the DEF pressures?

I tried to look up the fault code 4335 FMI 16 but I can’t find FMI 16. Can you double check

@@CarlosDieselElectric I was thinking on a punctured filter or something like that. On that thought, i searched for problems on the air line. nothing there; the air was ok at least on the metering unit. so, I cleaned the diesel-water separator and the air filter (for the mere fact that i thought they were dirty). the air filter very dirty... after that, the MIL went of by itself. i will change every filter this week to be sure. thank you for your time! have a nice day

@@BluQuark very nice. Glad it worked out.

Cali Greens just in time spent your looking at 2-3 hours (max). I charge $80 per hour. What have tried having done to clear the code?

Carlos Diesel Electric I actually changed this part. The PLV and my codes have cleared on their own(for now). I will see if they come back in a few days. Haven't been driving my rig past few days.

Cali Greens it sounds like your in the right track. Normally when I change this part I use the DDDL Software to check the DEF pressure and DEF air pressure and do a Parked Regen and confirm the code is clear but sounds like your already there. Congrats.

Carlos Diesel Electric how do you use the software to check the pressures and how do you know which par shoals be at what pressure you have a chart?????? PLEASE REPLY THANKS

@@CarlosDieselElectric I'd pay for this to be fixed. Same problem

4355 looks like it is related to DEF heater line. There are two of them that come off of the DEF tank. They are wrapped in a blue. What is the rest of the code? 4355 is just part of the code.

Carlos Diesel Electric no that’s actually all the code says spn 4355 So what are you advise me Should I clean those lines or replace them

Replace them. The fault code has nothing to do with the line being clogged or blocked. It has to do with the heater part of the line. There is something that has failed and that is most likely generating the fault code. You might need the software to clear once the lines have been replaced. But try replacing first.

Carlos Diesel Electric OK I will do that then I really think you so much 4 your help sir

Hey I finally found the problem the problem was not the DEF LIne heater but it’s was DEF harness wires And I found it by myself before I replace the DEF lines heaters I Find big damage to the wires and I just fix them and everything disappear

Need a little more information, what is the FMI part of the code? For example, you have SPN 4334 and SPN 4335 but I need the FMI part, that will help narrow it down.

I dont know how to find that🤷‍♂️

Ron Bravo not all Cascadia’s will have it. I believe 2013-2014 there was a change in the way the DEF was delivered. EPA10 and there is GHG14. You should go by your VIN. But if you do have it, it should be located behind and above the transmission.

What do I need to find there behind and above the transmission?

Ron Bravo how were you able to pull up the codes? Usually right after you see the SPN code. There should be two digits that follow. Depends on the Cascadia. Some have a different set up

You don’t need the software, just perform a parked regen and the code should clear

@@CarlosDieselElectric thqnk you 😊

@@CarlosDieselElectric how you doing I tried today to do a hard regen but won't let me do it. I can't clear that check light ... replace the limiting valve. Clean the metering unit out try to regen but qo t let me me. ??

@@CarlosDieselElectric You're not going to believe this I replaced that limiting pressure valve I remove the metering unit I clean it up clean the filters put it back together I was trying to do a reggen but it wouldn't let meThat was on Friday Today is Sunday I'm driving towards Virginia I stop a couple of times and the check engine light went off. By it self 🙏🙏🙏

@@rigobertohernandez2524 👍🏼 I started to replace both at the same time because they tend to go hand in hand. Glad it worked nicely done.

This code can be a pain to troubleshoot. I always start with this valve because it is fairly quick and inexpensive place to start. Hope they were able to get you back on the road.

The valve actually did fix the issue, it just needed a forced regen to clear the code.

@@loyfrye6664 what valve did they change?

They didn't, just forced a regen and that fixed it.

Did you fix it

Yes, once you install the PLV. Use your software to test. You might need to run a parked regen in order to clear the fault code.

@@huitusinevarez2788 yeah no longer code for DEF PRESSURE SENSOR. but it broke down last week for DPF FILTER code , I am going to delete it tomorrow Spent 6-7k fixing it already

I hear you, the after treatment can get expensive and frustrating especially after spending that much money.

@@CarlosDieselElectric whAt do you think about DELETES?

Tahar B : do you live in California or travel to California ? , I know someone that sale those laptops

@@martinmartinez1572 am not from us am in Canada

Tahar B : if you’re still looking for the software ; I have the guy cell number in case you want to contact him , I am sure that he can send it if like the price 🤗

@@martinmartinez1572 you can send it to me i will call nom thanks

Tahar B : 650 464 5642 ; Is gonna be better if you text him

You may need to perform a Parked Regen in order to clear the fault code. When I have this code I usually replace the PLV and the DEF Metering Unit. The two work together. But try doing a parked regen, you may need to use the diagnostic link software.

I did a regen and the code cleared and I’ve drove 1000 miles and hasn’t went back thanks brother

I have another code that comes on and off is Sys25 spn 1548 fail 5 would you happen to know what it means or maybe you’ve come across this issue before

That it is. These trucks get expensive fast. Don’t even compare to the old trucks as far as simplicity goes.

Conrad Woodbury when you say you can’t find it, do you mean on the truck? Or at the dealership?

@@CarlosDieselElectric on the truck it's a day cab

Conrad Woodbury usually right behind the cab. Near the cab air bags

Spent a hour under the Damn thing looked almost everywhere took off DEF meter box checked rechecked near cab air bags I can't figure out what I'm not seeing

Conrad Woodbury what is the last 6 of the VIN. I can ask my buddy at the dealer but I won’t be able get ahold of him until Monday