Exhaust System Regeneration

21980 Views 3 Replies 3 Participants Last post by Accused, Oct 24, 2014

staceyseeger

Discussion Starter · Oct 24, 2014

As I was driving yesterday this message showed up. I first called my "old school" diesel loving husband, who was at awe on what this meant.
So I called the dealer, but my translation back to my husband didn't make sense. They told me that the DEF fluid was being used to clean out the exhaust filter, which was full...but isn't this the purpose of the DEF fluid?
Can anyone explain to me exactly what was happening?
Thanks in advance!

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ED_Lover

· #2 · Oct 24, 2014

There's two emissions systems on these trucks. One is called the Diesel Particulate Filter (DPF) and the other is a catalytic converter. The DPF traps unburnt fuel in the form of small particles. Normally the exhaust temperatures should get hot enough to burn off anything caught in the DPF. However if it hasn't seen any hard driving or high RPMs there is the potential that it will get clogged. Basically the system checks the air pressure drop across the DPF and if that drop gets too high it goes into a mode called regeneration. What the system does is spray extra fuel into the cylinder during the exhaust stroke which will burn out the particles caught in the filter. In order for this to work you need to be driving at highway speeds (some load on the engine).

DEF is used as a catalyst to convert NOx into nitrogen, water, and CO2.

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staceyseeger

Discussion Starter · #3 · Oct 24, 2014

ED_Lover said:
There's two emissions systems on these trucks. One is called the Diesel Particulate Filter (DPF) and the other is a catalytic converter. The DPF traps unburnt fuel in the form of small particles. Normally the exhaust temperatures should get hot enough to burn off anything caught in the DPF. However if it hasn't seen any hard driving or high RPMs there is the potential that it will get clogged. Basically the system checks the air pressure drop across the DPF and if that drop gets too high it goes into a mode called regeneration. What the system does is spray extra fuel into the cylinder during the exhaust stroke which will burn out the particles caught in the filter. In order for this to work you need to be driving at highway speeds (some load on the engine).

DEF is used as a catalyst to convert NOx into nitrogen, water, and CO2.

Thanks for the insight! My husband will understand (and appreciate) this more than I will, I'm sure.
Yes, the message came on while I was on surface streets, but once I got on the highway at 65mph+, the % started dropping. It finally cleared itself after about 30 miles.

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