How to take care of your diesel particulate filter

Your diesel particulate filter (DPF) takes care of the environment, but do you know how to take care of it?

Diesel cars are well known for their great mileage, but to make them more environmentally friendly, they have a diesel particulate filter (DPF) fitted.

Since 2009, these have been found in exhausts to meet strict European emissions laws and targets. 

The DPF works like a catalytic converter and traps the solid particles produced by the diesel engine in a honeycomb matrix, stopping the soot from passing into the atmosphere.

But there's a catch.

To enjoy the benefits of a frugal diesel, the soot caught in the filter has to be burnt off regularly to keep the DPF working. When the levels in the filter reach a certain point, the DPF has to go through a regeneration process. 

As long as the DPF periodically cycles through this process of trapping particles and then burning them off, you'll likely have no issues with it.

What is DPF Regeneration?

The best way to kickstart this regeneration process is to regularly floor your car down the motorway. A good 30-50 minute blast at a constant speed will allow the DPF to heat up enough that the regeneration can take place.

Your car's Engine Control Unit (ECU) often aids in this process through 'active regeneration', and injects extra fuel into the engine to raise temperatures further.

How to tell when Regeneration is happening

You'll know when the regeneration process has started when you notice:

• A slight change in the engine noise
• Cooling fans have kicked in
• An increase in idle speed
• A hot smell from the exhaust

The regeneration can take anywhere from 10-30 minutes, and you shouldn't turn off the engine while it's taking place.

Why short journeys are the enemy

The DPF and the regeneration process isn't something you need to worry about on a daily basis, but you do need to watch out if your driving habits have changed.

Short runs are the mortal enemy of the DPF. The engine doesn't heat up enough for the regeneration to kick in, and the soot particles can build up to a level where only a garage can get it sorted.

How to keep your DPF happy

To prevent problems:

• Don't only nip to the shops or drive short distances to work
• Take your car on regular long drives at good speeds
• A good long drive regularly will sort the DPF right out and keep your motor ticking along smoothly

What happens if you ignore the warning signs

If the regeneration process doesn't happen when it needs to, a light will illuminate on the dashboard to let you know. As soon as this DPF light shows up, it's time to take the car for a good, long spin.

If you don't act:

• The regeneration process won't happen
• An engine warning light will appear
• You'll have to take the car to the garage for a Service Regeneration
• Your car might enter a 'fail-safe' mode and limit the engine speed to ensure the DPF and engine aren't damaged

The bottom line

If you're regularly taking your car on long journeys at a good speed, there's no need to worry, and your DPF will take care of itself.