Peterbilt 386 DEF system problem

[Trucker386]

Hello, I drive a 2012 peterbilt 386 and I have been experiencing lower mpg than usual and the truck asks for the regeneration to be perform at shorter time periods. When I place the truck in relay the truck feels like it is accelerated similar to when performing a regeneration. Cummins has determined that all of the DPF filters sensors are working but they cannot determine the condition of the filter or catalytic converter. Any help with this issue is appreciated.

 

[r3gulator3]

Hello, I drive a 2012 peterbilt 386 and I have been experiencing lower mpg than usual and the truck asks for the regeneration to be perform at shorter time periods. When I place the truck in relay the truck feels like it is accelerated similar to when performing a regeneration. Cummins has determined that all of the DPF filters sensors are working but they cannot determine the condition of the filter or catalytic converter. Any help with this issue is appreciated.

They should run all the troubleshooting for a 3582 fault code to include a Nox Efficiency test. I am willing to believe you have a partially plugged DOC, Decomp Tube or a catalyst that isn’t performing anymore. Very very common on that era of Cummins engines regardless of size.

 

[ironpony]

Have you done an oil analysis recently, and when was the last time the overhead was done?

 

[r3gulator3]

Also the 9L engine was prone for horrible cylinder wear especially when idled a lot. I have rebuilt several.

 

[Dfourlane]

No#1 trust no one....learn the system yourself...30 years as a tech I can tell you there is few that know cause in effect!
If you take the time the system is quite simple... clean you own filter... use YouTube

 

[NathanR]

I agree with the gentleman above that you should clean it.