Duramax L5P V2

[@nickayivor8432]

SUBSTANTIAL Joediagnostics Thanks 👍 amazing great tutorial ,take care and have a great day Joediagnostics From Nick Ayivor from London England UK 🇬🇧

[@joediagnostics]

Thanks Nick

[@gcmd5852]

We’re seeing L5p’s ( low mileage ) with P20ee’s on a regular basis lately. Being they’re all under warranty we’re having to make it a long and drawn out Diagnostic process. After drying out the SCR with a regen they clean right up. Must be saturated SCR.

[@joediagnostics]

Thanks for the comment, George, and the diagnostic tip. That explains the previous repair attempt on this one. It also explains why GM lists multiple regens as part of their SCR diagnostics. One thing I recently learned is how much ammonia an SCR can hold. I was driving it with the DEF injector unplugged and still seeing reduction of NOx rolling down the road. Kinda cool. I didn't think they would hold more than a few second worth, but they sure do.,

[@gcmd5852]

@@joediagnostics Yea one of the tests is running it with the injector unplugged. You can also run a regen then unplug it, drive it and if you see a reduction in Nox that would indicate a leaking injector ( might only leak when hot ). Some of the L5P’s will disable the reductant pump if it sees an open in that circuit so I’d make sure you have pump pressure. If the ecm disables the pump you can either plug in an old injector or simulate the 1 amp load. Another thing is replacing the reductant injector gasket ( one time use ) after performing a quantity test unless the injector gets replaced ( new injector comes with a new gasket ). According to GM engineering “if that gasket gets re used it can leak and cause the P20ee”. Great videos btw.

[@jflester5863]

Great video. Do you have a video or pictures of the failed scr, or removing scr. I'm going through this issue now on a 2018. New NOX2 and def injector and get 0 reduction. Most of the time nox2 is double what nox 1 reads. Thanks

[@joediagnostics]

Sorry. No video of the repair. When outlet NOx is double the inlet NOx, either the front NOx sensor is bad, and reading low, or the SCR is failed.