2022 Yukon Denali Diesel fuel injector failure

[Jay P Wy]

The 6.6's were the LB7's and it was the injectors, and the 2011 to 2017's with the CP4's. The LLY, LBZ, LMM, and LML saw very few failures from injectors or pumps.

LMLs had the CP4 and saw lots of pump failures. I have had all but one gen of the 6.6l (LLY). The LLY, LBZ & LMM had issues with running hot when towing at or near towing limits because GM didn’t put a big enough radiator in (fixed starting with LML). Ford still uses the CP4 and Ram recalled all the Cummins that had the CP4 and replaced it with a modified CP3. FYI the Denso pump is a 2000 bar pump (29000 psi). The CP3 is a 1600 bar pump and the CP4 is up to a 2000 bar pump per Bosch. I know GM, Ford and Cummins all operated the CP4 above that.
I agree that the LBZ was a good (if not best 6.6l due to the lack of emissions). The one I had was sold a 390k with no engine/trans issues.

 

[StephenPT]

Just an FYI - LM2/LZ0 use the Denso HP5 (2500 bar) with Denso G3.5S injectors.

 

[Morbo]

My 2022 Yukon Denali Duramax is in the shop now for a new injector for cylinder 5. It went out with about 25,000 miles on the odometer and did the same thing your's did with all the bells and whistles going off. Will post details when I have the paperwork on all of the work they performed.

Got my Yukon back today. It was not the injector that failed, but was the wiring harness that was the cause. Specifically the codes that were thrown were P0205 and P0300. The techs find bulletin 21-NA-149 that explained the wiring harness could be compromised if routed incorrectly (I'm paraphrasing my service order, not the bulletin). They found the wiring harness was "stretched and pinched" on the alternator bracket. They repositioned the harness, checked the connections and said it was good to go.

Runs fine now, but we will see.

 

[Geotrash]

Got my Yukon back today. It was not the injector that failed, but was the wiring harness that was the cause. Specifically the codes that were thrown were P0205 and P0300. The techs find bulletin 21-NA-149 that explained the wiring harness could be compromised if routed incorrectly (I'm paraphrasing my service order, not the bulletin). They found the wiring harness was "stretched and pinched" on the alternator bracket. They repositioned the harness, checked the connections and said it was good to go.

Runs fine now, but we will see.

Thanks for following up. Fingers crossed!

 

[steiny93]

They found the wiring harness was "stretched and pinched" on the alternator bracket. They repositioned the harness, checked the connections and said it was good to go.

So a quality of build issue, unfortunate

 

[Morbo]

The "repair" did not last one month (see posts 8 & 13). On Friday January 12, the dashboard did its bells and whistles thing and the engine began running rough. Took it in to the dealer today and a quick scan says bad injector. Hmmm, that was the initial diagnosis last time, but then they determined it was really the harness.

They have the Yukon now, but I'm not optimistic about their ability to find or fix the problem. Will update when I get it back.

 

[Morbo]

Got my Yukon back today, injector #5 was bad. That was the original diagnosis in November, but then they changed their minds and said it was the harness.

They replaced:
PART NUMBER
==============
injector 55506244
pipe 55514860
harness 40009103
gasket 55497083
seal 55496593
coolant 12346290

Ran perfectly on the drive home from the dealer. Will report back if any additional problems.

 

[steiny93]

I suppose it's possible that both the harness AND the injector have failed, at different times but on the same cylinder.