SCR Performance low, engine will derate IN..

so this kind of fault code scr efficiency is the most general fault you can think of anything from dpf being ready to clean and bake to the engine putting in to much smoke or not using enough egr will cause this kind of fault even bad injectors will, that being said this is not something that constantly gets monitored so all they are doing is reseting it and then you go 1000 miles and same issue until all the systems get monitored by the truck and it decides that something is wrong this code is a ##### to fix, it is very possible that having a plugged egr cooler could cause this fault but also if you do have a plugged egr cooler you should have a code for egr mechanical system or egr low flow, could be that the ports on the venturi tube are plugged happened a lot of times before, or even egr being stuck, this is all part of the diagnostic. have you changed you nox sensors if not this is the first step before you start spending thousands in egr and cooler. also if you need to clean EGR cooler i would highly suggest you just replace it they have one from DEX truck part same like OEM MK here in chicago sells it the kit is about 1100 if i'm not mistaking. i've had this code a #### load of times i've spent days trying to figure this out then change nox sensors and no more issues this is after replacing egr cooler cuz it looked plugged replacing egr valve cuz it had to much flow and replacing two injectors that were causing starting issues, and at the end two sensors not even 1k and it took care of the problem, One of my customers ended up going to volvo cuz i was busy he spent around 14K just to find out it was a bad NOX sensor.

 

you would be suprised how many issues these DPF and SCR have just from excessive idling, all my customers now i'm suggesting that they buy truks with APU not one major issue i think i have had one def line that was plugged that was about it, No APU nothing but headaches specially for the guys that go over the road and will idle a truck 10 to 12 hrs at a time, Just not made for this or you can say extra money for them in an APU system which with these new trucks is becoming more and more neccessary each day.

 

make sure it's egr and not egr cooler just make sure they diagnose it properly

 

Ok. Probably plugged from idling. Cooler exhaust contamination building up that clogs them.

 

That might be the only suggestion that he has had so far that I agree with. Better to change them in pairs.