Particulate filter not working

Jim Dunham · September 12, 2019

I have a 2018 GMC Sierra Duramax with 18000 miles. I do not remember The particulate filter regenerating itself since about it had about 7,000 miles. Is this a problem? Most of my driving in long distance pulling a trailer.

CamGTP · September 13, 2019

So it's not using any DEF fluid at all?

The 6.7 cummins work truck I drive will regen while I'm driving and I won't even notice it because I'm just cruising at freeway speeds.

redwngr · September 14, 2019

On 9/12/2019 at 9:29 PM, CamGTP said:

So it's not using any DEF fluid at all?

The 6.7 cummins work truck I drive will regen while I'm driving and I won't even notice it because I'm just cruising at freeway speeds.

On 9/12/2019 at 12:13 PM, Jim Dunham said:

I have a 2018 GMC Sierra Duramax with 18000 miles. I do not remember The particulate filter regenerating itself since about it had about 7,000 miles. Is this a problem? Most of my driving in long distance pulling a trailer.

DEF usage and DPR regeneration are separate discussions.

(LMM dmax 7.5 -'10, had a DPF and did regenerations, but did not have/use DEF)

DPF is to the soot particles.

DEF is to help in reduction of NOx in the exhaust. Reduction in permissible NOx has lead to use of DEF in these pickups, but also in ag engines, commercial truck engines. etc.

DEF is used whenever the engine is running -- the amount used is in ratio to the amount of fuel used. Some where between 1.5 and 2 gallons of DEF per 100 gallons of fuel.

Jim, you truck has definitely being regenerating. There is not message when this occurs. There is a fuel economy reduction during the regen. It will give a 'keep driving' message if it has not been able to reduce the soot load enough after several attempts.

It will give a 'keep driving' message if it has not been able to reduce the soot load enough after several attempts.

newdude · September 14, 2019

On ‎9‎/‎12‎/‎2019 at 12:13 PM, Jim Dunham said:

I have a 2018 GMC Sierra Duramax with 18000 miles. I do not remember The particulate filter regenerating itself since about it had about 7,000 miles. Is this a problem? Most of my driving in long distance pulling a trailer.

It's definitely been doing regens this whole time. If you don't have any warning or service messages, its working. Typically its one regen per tank of fuel. Highway unloaded driving would lower the frequency of 1 regen/xxx miles, loaded with a trailer would increase the frequency of 1 regen/xxx miles.

Edited September 14, 2019 by newdude

Jim Dunham · September 15, 2019

Thanks for your input. That answers my question and my concern. I had not seen the "keep driving while regen" for a long time so I wasn't sure that it was happening.

Regards

Jim D

Colossus · September 15, 2019

Good advice above.

redwngr · September 16, 2019

On 9/14/2019 at 8:16 AM, newdude said:

It's definitely been doing regens this whole time. If you don't have any warning or service messages, its working. Typically its one regen per tank of fuel. Highway unloaded driving would lower the frequency of 1 regen/xxx miles, loaded with a trailer would increase the frequency of 1 regen/xxx miles.

I believe the 700 mile number was for the LML's, but that the L5P regens more often than the LML's did.

(and also that the regens are shorter duration on L5P than on LML.)

Cowpie · September 21, 2019

On 9/12/2019 at 8:29 PM, CamGTP said:

So it's not using any DEF fluid at all?

The 6.7 cummins work truck I drive will regen while I'm driving and I won't even notice it because I'm just cruising at freeway speeds.

DEF (diesel exhaust fluid) goes to the SCR (Selective Catalytic Reduction) unit. The DPF (diesel particulate filter) is downstream from that. Isn't it sad that we have to deal with all this nonsense thanks to the guys who ran diesels who smoked all over the place and caused the bunny huggers to embrace making our lives miserable.

Edited September 21, 2019 by Cowpie