RFQT wonít pass - Chevy and GMC Duramax Diesel Forum
11-16 LML Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

 
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post #1 of 9 (permalink) Old 11-19-2017, 02:08 PM Thread Starter
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RFQT wonít pass

The warranty has timed out and the problems are getting costly, had the truck intothe dealer for ďservice emission systemĒ flashing on the DIC, and the check engine light on and now in limp mode, the code was P2202 nox sensor #1, the dealer changed it out and ran a regenthen areductantfluid test RFQT and it wouldnít pass, so the tech changed nox sensor #2, did another RFQT and it still didnít pass, then did a second regen, so now they want to replace theDPF because they say itís plugged, my question to the tech was, why didnít tech2 show that on the first diagnosis, he said he couldnít because there was no fault code for that, so, Iím thinking they are just pushing parts on me, or are they correct when they say they couldníttell the DPF is plugged? The truck ran fine lots of power asusual, 125000km on it 2/3 of that is highway driving, so the regens were happening, as the tech2 showed there was one done about 300km beforeI took it in, they also changed out the DEF fluid to be sure it wasnít expired, but I had put 20 litres in before the last trip. Iím not convinced itís a plugged filter, anyone know what else could be keeping the RFQT from passing? Thanks.
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post #2 of 9 (permalink) Old 11-27-2017, 07:11 AM
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GM warranty on the NOX sensors is 10 years 120,000 miles in the US. Should be the same in Canada.

The US clean air act mandates catalytic converter warranty for 8 years 80,000 miles (DPF is considered a CAT and falls under this warranty)

You may want to check the Canadian emissions regs and see if they have the same type of catalytic converter warranty.
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post #3 of 9 (permalink) Old 11-27-2017, 07:44 AM Thread Starter
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GM warranty on the NOX sensors is 10 years 120,000 miles in the US. Should be the same in Canada.

The US clean air act mandates catalytic converter warranty for 8 years 80,000 miles (DPF is considered a CAT and falls under this warranty)

You may want to check the Canadian emissions regs and see if they have the same type of catalytic converter warranty.
I called GM and they said the warranty on the sensors for my 2012 truck was not on the warranty extension coverage, but, after the sensors failed at 125525 km or about 77900 miles the mileage was still under the limit but it timed out on years, the sensors are definitely within the date range of the faulty sensors on the warranty extension coverage , I asked them why I never received a notice that the sensors on my truck were faulty, they kept repeating the same answer, my truck is not in the warranty extension coverage. Total BS as the sensors are clearly the defective ones in the notice, but Iím guessing they decided to play the wait game on faulty sensors installed after the notice was issued for other vehicles not on the warranty extension.
Link to notice, https://gm.oemdtc.com/1150/13386-nit...-chevrolet-gmc
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post #4 of 9 (permalink) Old 11-27-2017, 07:14 PM
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Whats the failure message when the RFQT finishes? The TECH2 will display that if it ends early on a failure.

Eric
'13 Denali 2500HD - Deleted, PPEI DSP/Tranny Tune, Jamo 4" w/ muffler, PPE downpipe, 2" Up pipes
'95 Tahoe 6.5TD - long gone
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post #5 of 9 (permalink) Old 11-28-2017, 04:21 AM
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There were updated calibrations for the NOx sensors that should have been done that specifically deal with the issue you are having. That is usually the culprit here, that or you actually have bad DEF (which is unlikely). Another possibility is that your DEF injector is somehow plugged and is no longer working.

There are 2 parts the DOC (Diesel oxidation Catalyst) and the DPF. If the dpf was plugged then the amount of soot in the dpf would be high. Your truck can monitor how much soot in the DPF by the DPDPF or differential pressure DPF sensor. Its the sensor on the passenger rear of the truck by the leaf spring that has the 2 rubber hoses to it. They can know the soot level in the truck by that sensor. At 43ish grams of soot your truck will start a regen. If your truck was not regening properly or too frequently there are codes for that, but your soot level in this case would be higher than 43g of soot.
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post #6 of 9 (permalink) Old 11-28-2017, 06:05 AM Thread Starter
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Whats the failure message when the RFQT finishes? The TECH2 will display that if it ends early on a failure.
All the Mechanic told me was it timed out, then he said it could be the air mixture ratio for the def and diesel, so he installed a new air breather filter, but didnít say there was any other message, he then went on to change the #2 nox and still couldnít get the rfqt to pass, so he did another regen. Two days later they called and said my truck was fixed and ready to go, but, when I started it up right away it went into limp mode, so, they added def fluid and said it need to be run for awhile at highway speeds, I told them to take for that run and left, Next day they told me I needed a new DPF.
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post #7 of 9 (permalink) Old 11-28-2017, 06:26 AM Thread Starter
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Originally Posted by SuperBlackTruck View Post
There were updated calibrations for the NOx sensors that should have been done that specifically deal with the issue you are having. That is usually the culprit here, that or you actually have bad DEF (which is unlikely). Another possibility is that your DEF injector is somehow plugged and is no longer working.

There are 2 parts the DOC (Diesel oxidation Catalyst) and the DPF. If the dpf was plugged then the amount of soot in the dpf would be high. Your truck can monitor how much soot in the DPF by the DPDPF or differential pressure DPF sensor. Its the sensor on the passenger rear of the truck by the leaf spring that has the 2 rubber hoses to it. They can know the soot level in the truck by that sensor. At 43ish grams of soot your truck will start a regen. If your truck was not regening properly or too frequently there are codes for that, but your soot level in this case would be higher than 43g of soot.
The mechanic showed me the def in a test tube device, he confirmed the injector was working correctly it was flowing at 47ml spec is 40-55 ml so that was working to spec. He did say on the road test the #2 nox was reading to high then it started to read normal, but he still changed it out, they knew these were the faulty sensors but didnít tell me, I have them now and the dates on them are 11-12-11, he also told me the truck did a regen 300km before it went in the shop and he said itís the nox sensors. But still the rfqt wonít pass.
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post #8 of 9 (permalink) Old 11-30-2017, 10:49 AM Thread Starter
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The mechanic showed me the def in a test tube device, he confirmed the injector was working correctly it was flowing at 47ml spec is 40-55 ml so that was working to spec. He did say on the road test the #2 nox was reading to high then it started to read normal, but he still changed it out, they knew these were the faulty sensors but didnít tell me, I have them now and the dates on them are 11-12-11, he also told me the truck did a regen 300km before it went in the shop and he said itís the nox sensors. But still the rfqt wonít pass.
Well I pulled the DPF off the truck today, and Iím 100% sure itís not plugged, I took a picture on the inlet side, can anyone tell me if this is a normal looking filter after regeneration? The exit end looked just the same, no build up of soot.
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post #9 of 9 (permalink) Old 01-08-2018, 01:44 PM
 
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hello, can you please provide specific reference where the Nox warranty is 10 years or 120,000 miles? I just got off the phone with the dealer, and then GM, and it is far less than that. can you help?

thanks.

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