If you are a self-employed tradesman, own a used van and only travel a few urban miles to work each day, then your van could be heading for an expensive problem – if it’s a Euro 5 model.

There are not many Euro 5 vans on the secondhand market yet, so this will be more of a problem in the next 2-4 years than it is at present.

Let me explain: To achieve Euro 5 emissions standards with diesel engines, van (and car) manufacturers use something called a Diesel Particulate Filter (DPF). Without getting into too much detail, these clog up if they are only used for short, low-speed journeys.

They need to be ‘regenerated’ from time to time, and this can only happen through sustained, high speed driving, when the DPF gets hot enough to work properly. In large conurbations like London, this can be awkward to do.

The problem, as many car owners have already discovered, is that if you only use your DPF-fitted diesel vehicle in town, it will never regenerate. If you ignore the warning light on the dashboard and keep on using it, the filter will eventually clog beyond all help and you will need an expensive replacement filter.

The solution for car owners is to buy a petrol-engined car, if your usage is primarily short, low-speed journeys. Petrols warm up faster anyway and are a more suitable choice for this type of usage.

However, van buyers don’t currently have this choice – apart from a few small models, it is diesel or nothing. This means that anyone buying a used, Euro 5 van should consider how it has been used, look for a good service history and remember that they themselves will need to give it a good run out of town occasionally to keep the DPF in good order.

Although the problem could affect the new owners of the van, it is more likely to affect second or third owners, as John Watts of CAP explains:

“This problem will mostly emerge in low speed, short distance operating cycles, typically undertaken in large conurbations. This type of operating environment could become even more of a problem for future owners since operational radius tends to reduce in the secondary market.

“A typical example could be a city-based self-employed used van owner who travels less than ten miles to site from home and stays all day. A continuous operation of this nature could result in a blocked filter and a potential replacement cost.”

Most manufacturers do provide guidelines indicating how the van should be used periodically to prevent the filter blocking, but such manuals are often missing from older secondary market vans.

CAP believes that widespread DPF blockage problems could affect used van prices but that dealers are already aware of the risks. CAP’s Watts said:

“If problems occur, how many will take their vehicles back to the supplier, expecting them to carry out repairs under warranty? Following on from that, how will the trade view vehicle values in the light of potential problems of this nature?

“CAP’s view is that the used vehicle trade need to be aware of the potential problem and ensure that vehicle documentation is complete, especially where a filter has already been replaced. Used van buyers in turn must be aware of the need for a functioning particulate filter for Euro 5 compliance and that problems may not be routinely covered under warranty.”

DPF blockage problems have already become commonplace with cars – many new van users use their vans enough to avoid this issue but it seems certain to rear its head eventually, especially in large cities.