Diesel particulate filter: follow these tips if you want to avoid breakdowns!

If you have a diesel car with a particulate filter and you do a lot of driving around town, you will almost certainly end up with problems. Here is how to avoid them.

Say no more. You have a diesel car, and at some point the workshop has probably told you that you should get out on the open road more. They may have mentioned the particulate filter, which they probably referred to as FAP or DPF, depending on the acronym used in English or French. But you still don’t quite understand it…

No wonder. In fact, here we told you 10 reasons why you may end up hating the particulate filter in your diesel. The main problem is that you probably only make short trips around the city. That makes you the typical user who would have needed a petrol car.

Firstly, because in those situations, and for this type of use, diesel loses many of its fuel-consumption advantages. On the one hand, you run into a real “blockage” in the exhaust when the filter is unable to regenerate (you will understand this better later on). On the other hand, these filters need additional fuel injections to attempt regeneration.

But that is no reason to change your car now…

What you need to know about how the particulate filter works

The workshop did not want to beat around the bush. When they tell you that you “need to get out on the open road more”, they have a technical basis for saying so, even if they may not have explained it in full. To make it easy to understand, the particulate filter is a component placed in the exhaust line, made up of a bundle of fine ceramic tubes through which the gases produced by combustion pass.

The gaseous particles can pass through those tubes, but the rest stay trapped there, waiting to be burned and gasified, which is known as “regeneration”.

What happens is that, for that regeneration to take place, the exhaust gases need to reach a high temperature, around 500 degrees Celsius or more. That temperature is hard to reach on short trips around town. That is why you need to get out on the open road more.

The process sometimes creates a vicious circle: in order for the exhaust gas temperature to rise and the filter to regenerate, one of the things the engine does is inject extra fuel.

But if you drive very short trips and the gases never get hot, the engine may end up producing even more particles (there is more fuel to burn). To prevent this, the other headache for many diesel car owners comes into play: the Adblue additive.

Here we tell you the most important things about Adblue, because although you may not know it, neglecting the additive can leave you stranded. Put very simply, Adblue lowers the temperature needed for the particles trapped in the filter to burn off, so that the filter regenerates.

How to avoid problems with the particulate filter

If you have understood the above (and if not, never mind, the following still applies), you will understand much better the following tips you should follow to avoid problems, faults and breakdowns with the particulate filter in your diesel.

1. The workshop has already told you, and so have we: get out on the open road from time to time. In general, a stretch on a motorway or dual carriageway at more than 80 km/h (better still if you keep the engine turning between 2,000 and 3,000 rpm) for around 15 or 20 minutes should be enough.

Of course, this will depend on how much you use the car in town. You can also use mileage as a guide: get out on the open road every time you cover about 250 km without leaving the city.

2.- Use a good-quality oil that meets the specifications recommended by the manufacturer for your car’s engine. If you don’t, the additives in the lubricant could leave ash that is very hard to gasify during regeneration, and that can clog the filter, causing the corresponding breakdown and a trip to the workshop.

Here you have 15 questions about your car’s engine oil that you should know the answers to.

3.- Keep an eye on the Adblue warning light (if your diesel uses it; not all diesel engines with a particulate filter use Adblue), and add additive if necessary.

4.- If anything behaves abnormally, go to the workshop. If you do so in time and the problem lies with the particulate filter, often a forced regeneration (the car is hooked up to diagnostic equipment) is enough or, in the worst case, a cleaning of the filter, which is much cheaper than replacing it with a new one.

Some symptoms that something is wrong with the filter are increased fuel consumption, oil level rising above the maximum between services, or smoke from the exhaust pipe.

Related information of interest

• Engine oil: why it is so important for your car
• 10 tips to avoid nasty surprises when taking your car to the workshop
• These are the reasons your diesel’s consumption may increase