eli5: what is DPF Regeneration in cars?


Today I came across my car showing the message “DPF regeneration in progress”

when it pops up the engine isn’t idle and engine noise increases.

What causes it? What you should do when the message pops up?

In: 9

There’s a thing in a diesel exhaust system called a Diesel Particulate Filter (DPF). When the truck is working at low RPM a lot (like when you’re stuck in traffic), the filter accumulates some soot from the burning fuel. If you drive at high RPM, the soot will burn off and you don’t have to worry about it. But if you’re stuck in traffic or something, the engine needs to take measures to burn that soot off by running at higher RPMs for a while.

Some trucks will have a way for the driver to start it manually, but it will usually happen automatically. Letting that filter breathe freely keeps the engine running smoothly and efficiently.

DPF is a filter that removes soot particles from the exhaust, when you do a lot of slow driving it clogs up and the engine runs a special regeneration program that revs the engine and add extra fuel to heat the filter and burn off the soot. You don’t need to do anything

That’s when your diesel car let out all the toxic, carcinogenic particles from its exhaust system to the enviroment.

DPF = Diesel Particulate Filter

The note changes because it is delaying the burn of the diesel, so it leaves the cylinder head still burning.
Normally it would be injecting earlier, so it can do as much burning and expansion in the cylinder, but the regens will delay that or add a little diesel after the main squirt.
The diesel burning through the exhaust increases the exhaust gas temperatures, and will get the DPF to 800degC / 1500F which should be hot enough to burn the soot.
That’s also why the sound of the exhaust changes too.

When it does happen, carry on driving as normal, or if you get the chance, cruise at a steady speed and it’ll stop after maybe 5-10 mins and the DPF soot filter in the exhaust should be cleaner.

If you have a Volkswagen from the Dieselgate scandal time frame, it causes a lot of issues. If your car isn’t under warranty, you should just have a mechanic remove it.