Catalytic Converters

A catalytic converter (colloquially, “cat” or “catcon”) is a device used to reduce the toxicity of emissions from an internal combustion engine. First widely introduced on series-production automobiles in the U.S. market for the 1975 model year to comply with tightening EPA regulations on auto exhaust, catalytic converters are still most commonly used in motor vehicle exhaust systems. Catalytic converters are also used on generator sets, forklifts, mining equipment, trucks, buses, trains, and other engine-equipped machines. A catalytic converter provides an environment for a chemical reaction wherein toxic combustion by-products are converted to less-toxic substances.

Diesel Particulate Filters

Diesel Particulate Filters (commonly referred to as DPFs or FAPs) are becoming a commonplace item on Diesel vehicles. It is a device which removes diesel particulate matter (or soot) from the exhaust gas of a diesel vehicle, therefore reducing the particulate emissions.

How do DPFs work?
Unlike a Catalytic Converter a DPF is not a flow through device, and works by forcing the gasses to flow through the filter. As the channels of the filter are blocked at alternate ends, the gasses are forced to flow through the cell walls in order to exit the filter. As the cell walls are porous, the gasses are allowed to pass through, but the particulate matter is deposited on the cell walls. This ensures that only the clean exhaust gasses can exit, and the particulate matter is trapped in the filter.

BM Cat’s filters are made from Cordierite, a ceramic material that resembles the internals of a Catalytic Converter but alternate holes are blocked.

DPF Maintenance

DPFs need to be regularly maintained to prevent a build up of soot in the filter. Effectively, they are a “soot trap”, so in order to prevent it becoming blocked and affecting the running of the vehicle, it has to be cleaned. This is done with either the use of passive regeneration or active regeneration. A warning light on the dash will warn the vehicle owner if the DPF is becoming blocked and regeneration is needed. Passive Regeneration – occurs on long journeys when the exhaust temperature is high and the soot burns off naturally. For vehicles which unfortunately don’t get this kind of use, Active Regeneration is needed. Active Regeneration – occurs when the level of soot in the filter reaches around 45%. The ECU makes small adjustments to the fuel injection timing and increases the exhaust gas temperature. This increases the exhaust temperature which then initiates the regeneration process, burning away the soot trapped in the DPF. Some types of vehicle (especially Citroen and Peugeot models) use a fuel additive to aid the regeneration process. The fuel additive is added to the fuel tank every time the vehicle is filled with fuel. It is common in vehicles where there isn’t enough room to locate the DPF close to the engine where the exhaust gasses are hottest. The fuel additive lowers the temperature at which the soot particles trapped in the filter ignite and burn off. This allows regeneration to take place at a lower temperature than normal.

DPF Facts and Fitting Advice

It is believed they will need to be fitted to all diesel vehicles to enable them to pass the upcoming Euro V Regulations.

DPFs are normally used in conjunction with a catalytic converter

DPFs can remove 85% or more of the soot and ensure no visible smoke is emitted.

Too much soot in the filter can lead to increased back pressure and potentially cause damage to the engine.

DPFs are direct fit items and should be fitted following the same advice as when fitting a catalytic converter. Other points to follow are;

  • Do not use exhaust paste
  • Ensure all joints are properly sealed.
  • Ensure the fuel additive tank is full.
  • Check all sensor tubes are free from blockages.
  • Check the fuel injection system is working correctly.
  • The ECU has to be reset by a main dealer or independent garage once the DPF unit has been changed to clear any fault codes/service warnings.


An exhaust system is usually tubing used to guide reaction exhaust gases away from a controlled combustion inside an engine. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system design, the exhaust gas may flow through one or more of:

  • Cylinder head and exhaust manifold
  • A turbocharger to increase engine power.
  • A catalytic converter to reduce air pollution.
  • A silencer to reduce noise

Exhaust Gaskets

Component Distributors stock Klarius’ full range of Exhaust Gaskets and Mountings. A gasket is a mechanical seal that fills the space between two objects, generally to prevent leakage between the two objects while under compression.

Exhaust Gaskets

Component Distributors stock Klarius’ full range of Exhaust Gaskets and Mountings. A gasket is a mechanical seal that fills the space between two objects, generally to prevent leakage between the two objects while under compression.

Exhaust Paste

Bangor Autoparts stock Klarius Exhaust paste and putty.

Our exhaust Jointing Paste is specially formulated for the assembly of all exhaust systems as well as flues and boiler pipes.

  • Lubricates joints for fastest, simplest assembly
  • Self sealing to stop dangerous fumes
  • Hardens with heat and withstands temperatures of up to 1,000ºC

Our Exhaust Jointing and Repair Putty is asbestos-free and provides a gas-tight seal to all joints.

Oxygen Sensors

Automotive oxygen sensors, colloquially known as O2 sensors, make modern electronic fuel injection and emission control possible. They help determine, in real time, if the air fuel ratio of a combustion engine is rich or lean. Since oxygen sensors are located in the exhaust stream, they do not directly measure the air or the fuel entering the engine, but when information from oxygen sensors is coupled with information from other sources, it can be used to indirectly determine the air-to-fuel ratio.