Back to Home

  1. Home
  2. Diesel Particulate Filter and Adblue Solutions for Diesel Engines

Diesel Particulate Filter and Adblue Solutions for Diesel Engines

Diesel Particulate Filter (DPF)

Following changes to new car emissions legislation in 2009, Euro 5 emission standards have made particulate filters as commonplace in diesel car exhaust systems as catalytic converters are on petrol cars.

The goal was an 80% reduction in diesel particulate (soot) emissions, but the technology does have potential problems. Roadside assistance patrols frequently attend cars with the particulate filter warning light illuminated, which normally indicates a partial blockage of the DPF filter.

Clearly, changes to driving styles may be required to gain the maximum benefit from these emission-reducing systems.

How Do Diesel Particulate Filters Work?

Diesel particulate filters (DPFs), or 'traps,' catch soot in the exhaust.

As with any filter (like a vacuum cleaner bag), they must be emptied regularly to maintain performance. For a DPF, this process is called 'regeneration'. The accumulated soot is burned off at high temperatures, leaving only a tiny ash residue. Regeneration may be either passive or active.

Passive Regeneration

  • Passive regeneration happens automatically on motorway-type runs when the exhaust temperature is high.
  • Many cars don't get this type of use, so manufacturers incorporate active regeneration systems.

Active Regeneration

  • When soot loading in the filter reaches about 45%, the engine management system (ECU) increases the exhaust temperature to initiate regeneration.
  • If the journey is stop/start, regeneration may not complete, and the warning light will illuminate, indicating a partially blocked DPF.
  • To clear the warning light, drive for 10 minutes at speeds above 40mph.

If ignored, soot loading may reach 75%, triggering additional dashboard warning lights. At this stage, a dealer visit for regeneration is required.

Expensive Repairs

Ignoring warnings can result in further soot buildup and the need for a new DPF, which costs around £1,000.

Mainly Town-Based Driving

If your driving is mostly town-based with stop/start traffic, consider choosing a petrol car to avoid the risk of incomplete DPF regeneration.

DPF Additives

  • The most common DPF type integrates an oxidising catalytic converter close to the engine, where exhaust gases are hotter to enable passive regeneration.
  • If space near the engine is unavailable, some manufacturers use a DPF that relies on a fuel additive to lower the ignition temperature of soot.

How It Works

  • The additive is stored in a separate tank and mixed with fuel during refueling.
  • A litre of additive treats 2,800 litres of fuel, covering approximately 25,000 miles at 40mpg.
  • Regeneration occurs every 300 miles, taking 5 to 10 minutes to complete.

AA Experience

The AA has observed that DPF systems sometimes fail to regenerate, even on cars used primarily on motorways.

  • In cars with a very high sixth gear, low engine revs may prevent sufficient exhaust temperature.
  • Occasional harder driving in lower gears can help burn off the soot.

Check the Handbook

If your car has a DPF, consult the vehicle handbook to understand what actions to take if the warning light illuminates and whether your driving style needs adjustment to ensure DPF efficiency and lifespan.

AdBlue® Solution for Diesel Engines

AdBlue® is a registered trademark for a solution that reduces emissions from diesel vehicles, helping them comply with Euro 6 emissions standards.

Driver Responsibility

  • Topping up AdBlue® is the driver’s responsibility, along with covering all associated costs.

What Is AdBlue®?

  • AdBlue® is a solution of 32.5% high-purity urea and 67.5% de-mineralised water.
  • It is not a fuel or a fuel additive but a separate solution used during the Selective Catalytic Reduction (SCR) process.

How Does AdBlue® Work?

  • AdBlue® is stored in a dedicated tank in the vehicle.
  • It triggers a chemical reaction during the SCR process to reduce nitrogen oxide (NOx) emissions.

AdBlue® and Lex Autolease Maintenance Contracts

  • AdBlue® is considered a consumable by leading manufacturers and is typically not covered under maintenance contracts.
  • Some vehicles include an AdBlue® check and top-up during scheduled servicing. For these vehicles, Lex Autolease covers the top-up cost during the service only.

When Does AdBlue® Need Topping Up?

  • AdBlue® lasts for approximately 3,500 to 13,000 miles, depending on driving style and conditions.
  • The average AdBlue® consumption is about 5 litres per 100 litres of diesel.
  • Vehicles are equipped with warning systems to notify drivers when refilling is required. Do not ignore these warnings.

Important Points

  • If AdBlue® runs out, the vehicle cannot be restarted after the engine is switched off.
  • Refilling the AdBlue® tank is mandatory to restart the engine.

How Is AdBlue® Topped Up?

  • The location of AdBlue® tanks varies by manufacturer (e.g., boot, fuel filler, or under the bonnet).
  • Manufacturers recommend professional top-ups to avoid errors.

Cost of AdBlue®

  • Prices vary by manufacturer and quantity purchased.
  • Small quantities may cost £5.50 per litre or more, with a full tank refill costing up to £90.00 when including labour charges.

How to Check If Your Vehicle Requires AdBlue®

  • It is difficult to identify if a vehicle uses AdBlue® by its model description alone.
  • Check with the manufacturer to confirm if your vehicle requires AdBlue®.