The Symptoms of a Blocked DPF Filter

Modern diesel cars are all fitted with a Diesel Particulate Filter, or DPF. A DPF is designed to help your car reduce its emissions by filtering out excess carbon waste from the engine’s exhaust system. A DPF is a legal requirement of all diesel car drivers, and while the filter is necessary for the efficient running of your engine, they can often cause issues when they become blocked. Unluckily for us, DPF filters love getting blocked. In this article we’re going to go over what happens when you experience a blocked DPF, and how to fix and avoid a blockage in the future.

Symptoms of a Blocked DPF Filter

1 – Your Car Feels Weaker

Because a DPF blockage directly affects your exhaust system and its ability to remove gas from your engine, this then stops your engine from working as powerfully and as efficiently as it could. No matter how much acceleration you pump into the engine, it will still feel weak due to its inability to expel the excess gas. The engine will use more of its energy trying to push the exhaust fumes out through the DPF, which leaves less energy for acceleration. This in turn means that. . .

2 – You Burn Through Fuel Quicker

Because your engine is not working as hard, you will naturally accelerate more to make up for the lost power. Not only does a blocked DPF filter make your engine use more fuel, the acceleration that you do is not as powerful due to the engine not being able to expel its emissions. This double whammy of decreased efficiency causes you to spend more money on fuel along with tiring your engine out at a must faster rate. Imagine forcing an old horse to run faster than it ever has in its youth, something will eventually give out.

3 – Your Engine is Harder To Start

When a blocked DPF causes a build up of gas in the engine that can’t go anywhere, this also causes a large build up of pressure in both the engine and the DPF itself. If this happens, your engine will simply not want to start until that pressure is released. This is actually a good thing, as if you were to drive the car with that amount of pressure built up inside the engine, this could cause major damage to the engine and potential ruin your DPF altogether. This can also be more expensive than a simple DPF cleaning service.

4 – Issues With Your Turbocharger

A blocked Diesel Particulate Filter will hinder the flow of gas through the exhaust system, preventing the gas from passing through the exhaust at the right rate. This causes the temperature of the gas to increase if it is not expelled fast enough, which heats up the housing around the turbine. This can cause damage to your turbocharger such as the gas leaking directly from the turbocharger because it has nowhere else to go. This then causes oil leaks and a decrease in efficiency with the way the turbocharger works. A DPF blockage may also cause the oil that is stored in your turbo system to carbonise, which can be dangerous for your engine.

5 – The Engine Smells Strange

All this gas that has built up in your engine will not smell overly nice. Not only is this dangerous due to the raised potential of engine damage or even fires, but the odour that comes from these gases cause anyone who inhales some of these gases to become ill. Also, the smell may also disguise other tell-tale smells that arise if any other issues are affecting your car, such as a burnt out clutch or an oil leak.

How To Avoid a Blocked DPF

So how do you avoid your DPF becoming blocked? This can be quite difficult for many drivers, especially urban motorists that predominantly drive in the city. City driving comes with a lot of stopping and starting, and rarely gives you the chance to get up to any major speeds. Short journeys are also problematic as this doesn’t give the engine enough time to reach a temperature where it can burn away the blockage. If you are a city driver, it can be a good idea to take your car for a spin on the motorway once in a while to give your engine the heat and power it needs to blow away any build up of waste within the DPF filter.

It is also a wise move to get your fuel injectors checked to ensure that they are sending the correct amount of fuel to the engine and not tipping your air:fuel ratio too far in the favour of fuel. When you fill up the engine with engine oil, make sure that you are getting the right kind of oil that helps your engine burn away the DPF residues. Look for oil that has low SAPS (Sulphated Ash, Phosphorus and Sulphur). These oils have a lower rate of ash formation, and therefore will not clock your DPF as quickly.

What To Do if your DPF is Blocked

However, no matter how hard you try, your DPF will eventually become blocked. This is due to the design of the component not yet being perfected. When you see the DPF warning light appear on your dashboard or experience any of the above symptoms, simply get in touch with DPF Cleaning Express for one of the most efficient, effective and affordable DPF regeneration services in the UK.

We offer a complete DPF rejuvenation to factory standards, complete with our Flash Cleaning service. The DPF Flash Cleaner is the currently the most effective and efficient DPF cleaning method on the market, and is used by most major dealers. Here at DPF Cleaning Express, we have access to the same equipment and industry methods used by dealer technicians and manufacturers, which gives us the ability to offer a comprehensive DPF cleaning service at a fraction of the price of major dealers. We offer our services throughout the UK from our HQ in Sheffield, regularly receiving DPF filters shipping from all over the country, purging them of any impurities and shipping them back within 3 days. Get in touch with our team today to learn more.

Speak to an expert

Got concerns about your DPF? Whether it’s a repair, a replacement or just some advice about your filter, we can help. Get in touch with us using the form below, drop us an email or give us a call on 0114 3490923. We look forward to hearing from you.


0114 3490 923


Unit 3, The Gables
Holywell Road
Sheffield, South Yorkshire
S4 8AR