Most Common DPF Problems - JLM DPF Doctor
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Most Common DPF Problems

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Most common DPF problems

The main reason the Diesel Particulate Filter was invented was to clean up the diesel car reputation (Euro 5 Emissions, 2009). Emissions from diesel cars are a big concern worldwide and thanks to the DPF technology, diesel cars became much cleaner. (NO we are not giving our opinion about the VW The scandal cheating pollution emissions tests).

DPF’s are great for the environment but only if they reach the correct operating temperatures to regenerate every once in a while. Similar to EGR problems, the DPF can become clogged up from city driving where the car does not get up to it’s normal operating temperature.

How does a DPF Work in Diesel Cars?

Regardless the brand of your car, the process works in much the same way: exhaust gases pass through the DPF, leaving large soot particles behind. Unfortunately, it’s these particles that can cause problems. The soot can block the filter, stopping the engine from running and leaving you with a repair bill that can cost you thousands of euros/pounds or dollars etc.

To stop this from happening, the soot needs to be burned at a high enough temperature to turn it into smaller ash particles, which can then be expelled from the system. It’s when this cleaning, or ‘regeneration’ process is interrupted that the majority of issues with DPFs occur.

There are 3 different types of DPF regeneration, which are active, passive and forced.


What causes DPF failure?

Unfortunately many diesel car owners do not realize how they are actually causing a blocked DPF themselves. The main reason for DPF’s failing is due to car owners not doing enough highway miles and driving too frequently in city areas.

How long until a DPF will fail is hard to tell because if you regularly use JLM DPF cleaner as a preventive additive you might never encounter problems!

The most common reasons for DPF failures are:

  • Short journeys where the engine doesn’t reach optimum operating temperature
  • Clogged EGR Valve increasing diesel soot passed to the DPF
  • Faulty fuel injectors sending too much fuel to the air/fuel mixture
  • Incorrect engine oil upon servicing the car – (Low Ash required for DPF Cars)
  • Turbo failing with oil dripping into the DPF
  • High mileage car that will find regeneration harder

Symptoms of a Block DPF Filter

As the majority of DPF’s are installed on newer cars, you will more than likely have a trip computer. Error codes such as the DPF light or EML (Engine Management Light) will be the first symptoms of a failing DPF.

However, sometimes these warning lights can be false alarms and you should try clearing the fault using a OBD2 diagnostic tool. If the warning light continues to display, you will notice the following symptoms:

  • Loss of power
  • Reduced fuel economy
  • Poor throttle response
  • Harder or failure to start
  • Limp mode (most likely)
  • Bad smells

How to Clear a Blocked DPF and Keep it Clean

The cost of cleaning or replacing your DPF sounds scary but you can forget this following some simple driving habits. The main reason DPF’s get blocked is due to short trips and town driving.

With that in mind, here are 7 ways to fix a blocked DPF:

  1. Add JLM DPF cleaner into your diesel tank.
  2. Drive Faster. If you are driving slowly everywhere in your large diesel, the DPF will become blocked. Increase your speed and plant your foot to floor to when accelerating to increase exhaust temperature and clear soot levels.
  3. Increase Your RPM. If the DPF light is on, your best bet is to drive at high RPM’s for a prolonged period until the warning lights turn off. This will increase the gases going through the DPF, thus clearing it and increasing the temperature.
  4. Check the EGR Valve. If you have problems with your EGR valve, it will be even harder to clear the DPF. Fix the EGR issue and then try the other steps.
  5. Avoid City Driving. If possible, you should avoid slow traffic where possible, especially if you are nearing your DPF limit or have the light currently on.
  6. Use High Quality Fuel
  7. Consult your Local JLM DPF Doctor to help fix your DPF Problem

If you are currently in limp mode, adding JLM DPF cleaner to your fuel tank and driving at high RPM (step 2) will be your best chance of getting out of limp mode. Once you have normal power, go for a long drive.

Always get your error codes read by a JLM DPF Doctor that has all the necessary diagnostic tools ASAP!

Voulez-vous devenir un médecin JLM DPF?

Le réseau JLM DPF Doctor offre un diagnostic professionnel du filtre DPF et du filtre à particules diesel, afin de résoudre la cause profonde de votre problème DPF. Faites partie de l’équipe!

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Möchten Sie ein JLM DPF Doctor werden?

Das JLM DPF Doctor Network bietet professionelle DPF-Reinigung und Dieselpartikelfilter-Diagnose, um die Ursache Ihres DPF-Problems zu beheben. Sei Teil des Teams!

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Wil je een JLM DPF Doctor worden?

Het JLM DPF Doctor Network biedt professionele DPF-reiniging en dieselpartikelfilterdiagnostiek om de hoofdoorzaak van uw DPF-probleem op te lossen. Maak deel uit van het team!

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Want to become a JLM DPF Doctor?

The JLM DPF Doctor Network offers Professional DPF Cleaning and Diesel Particulate Filter diagnostics, to solve the root cause of your DPF problem. Be part of the team!

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