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Duramax Fifth Generation: 2011-2016 (LML) Discuss the fifth generation (2011-2016) of the 6.6L Duramax diesel engine & associated components. Engine related discussion ONLY.

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Old 02-02-2014, 04:36 PM   #21 (permalink)
Ted White
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Thank you gmshopforeman and 01dmaxunit27 for indirectly pointing out the error in my post about P0420. All of my experience with P0420 is related to the use of Mexican diesel, where the higher sulfur diesel temporarily "poisons" the DOC, along with the SCR. Owners typically see DTC P20EE at the same time, and the problem usually clears itself after the next regeneration, when high exhaust gas temperatures burn the sulfur compounds out of the system. I have therefore always associated P0420 with out-of-spec NOX. This may be true while in Mexico, but is not necessarily true while in the USA or Canada.

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Old 03-25-2014, 10:52 AM   #22 (permalink)
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Originally Posted by gmshopforeman View Post
I've had a few trucks in with the P0420 (Catalyst System Low Efficiency) stored. Looking at the ECM Freeze Frame/Failure Records you can see that it will set when a DPF regen is enabled. Everyone in here for this code has been cause by poor or no fuel delivery from the Indirect Injector. With not enough fuel being delivered to the DOC it goes not light off properly, thus we don't get the heat required for a proper regen event. Have your Dealer perform the Indirect Injector Quantity Test in Service Information.

Well after a two day visit to the dealership a bad urea injector was replace and and the sensor for the cat. One month later all is still good?

Black 13 LML CC/SB

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Old 08-02-2017, 05:33 PM   #23 (permalink)
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Is this code covered under warranty? I just had my EFS sensor replaced short time later I receive a warning " continue driving exhaust filters are being cleaned"... two weeks later that message stops.. a month in a half goes by, know I am getting this message.

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Old 08-02-2017, 08:17 PM   #24 (permalink)
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Originally Posted by PutterT View Post
Is this code covered under warranty?
Do this so we can help you better.
Yes, you should have this some where.
Emission Control Systems Warranty
Emission Warranty Parts List
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Nasta Nerf Bars, Line-x, Rancho RS9000XL Shocks, Firestone air bags, Fold-a-cover,
Good/Year Wrangler S/A 265/75/16 E
Transgo Jr. PCV Reroute kit, Trans Line Repair Kit By Dirty Hooker Diesel,
Custom Perf/Tow Tune by Kennedy
2019 Arctic Fox 27-5L 10,500 dry weight
UAW Local 699 Retired Test Technician

Last edited by Ramblinrodney; 08-02-2017 at 08:36 PM.
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