Tag Archives: Replacement

What is a DPF and What to check when replacing.

What is a Diesel Particulate Filter (DPF) ?

A Diesel Particulate Filter (DPF) is a device designed to remove diesel particulate matter or soot from the exhaust. Unlike a Catalytic Converter, a DPF is not a flow through device. Exhaust gases are cleaned by passing through the walls of the DPF leaving particulate matter to accumulate on the inlet face of the DPF. Once the DPF reaches a certain level it must be cleaned. Through filter “regeneration” these soot particles are burnt off at high temperatures.


Advice for DPF care

– When the DPF warning light illuminates you must follow the instructions in the owners manual immediately. Failure to comply could lead to a blocked DPF.

– Active DPF’s that use an additive fluid to assist in the regeneration process must never be driven without this fluid, as this could lead to a blocked DPF.

– When fitting a new active DPF or topping up the additive, the control unit must be reset to New DPF / Refilled Additive. (See Zetti DPF Tool section)


– It is not advisable to run a DPF vehicle on biodiesel.

– Always check the engine oil for diesel contamination, which can occur during the regeneration process. If the oil is contaminated then the engine oil and filter must be replaced.

What to check when replacing the DPF

Follow these steps when replacing a DPF:
  1. Ensure the root cause of the problem is rectified before replacing a DPF
  2. Use new mounting brackets
  3. Line up the DPF perfectly to avoid vibrations or anomalies in exhaust pressure
  4. Don’t hit the DPF with hammers or other rigid tools to avoid the monolith from breaking
  5. Do not use exhaust paste on the DPF
  6. Replace the engine oil of the vehicle
  7. Update the engine management software to tell the vehicle it has a new DPF fitted. (See Zetti DPF Tool article)

What is a Catalytic Converter and What to know when replacing.

What is a Catalytic Converter & How does it work?

Introduced to Australian motor vehicles in 1986, Catalytic Converters were fitted to unleaded petrol vehicles to clean up the noxious exhaust gases produced during operation. The role of the Catalytic Converter is to control the harmful emissions from the combustion process by converting the Hydrocarbons (HC), Nitrogen Oxides (NOx) and Carbon Monoxide (CO) into Carbon Dioxide (CO2), Nitrogen (N2) and Water Vapour (H2O).


The Catalytic Converter is designed to last the lifetime of the vehicle, but this is not always the case.** The premature failure of the Catalytic Converter could be attributed to poor tuning of the vehicles ignition, not servicing the vehicle at regular intervals, road impact damage, driving through deep water or using non-compatible fuels and additives. These conditions need to be avoided by the owner of the vehicle.

* Not all cats are designed with heat shields.
** Different materials used in the manufacturers construction process may attribute to shorter life span of the cat.

Replacing the Catalytic Converter… What you need to know.

1 – Ensure any engine or emission faults are rectified before replacing the catalytic converter. Failure to correct a pre-existing emissions problem could result in a damaged catalytic converter.

2 – It is recommended to replace the Oxygen Sensor when the Catalytic Converter is replaced. For correct operation of the engine and Catalytic Converter, the vehicle must be fitted with an Oxygen Sensor. When combustion gases are flowing through the exhaust, they are picked up by the Oxygen Sensor and a signal is sent back to the ECU. This signal then helps to control the air/fuel mixture entering the combustion chambers for a better ‘burn’.


3 – Always use new mountings, gaskets and bolts to avoid leakage or fitment issues. This will ensure the correct fitment first time around. Always recommend new studs, bolts and nuts when replacing any part of the exhaust system.

4 – When replacing a Catalytic Converter it is essential to examine the complete exhaust system from the manifold to the tail pipe for damage, corrosion or leaking/blowing. Repair or replace as required. A simple test is to have the vehicle running at idle whilst on the hoist. Use a shop rag to block the tailpipe (without burning your hand) and listen for any exhaust leaks in the system. Two people will be required for a closer inspection of any joins/pipes. The use of a vapour or smoke machine will accuarately locate any exhaust leaks.

5 – After replacing the cat converter be sure to run the vehicle at 2500rpm until the electric fans kick in. Then run the vehicle for a further 1 minute until the new catalytic converter temperature reaches 350˚C to ensure it is lighting off and functioning properly .

6 – Do not use exhaust sealant upstream of the Catalytic Converter. This can be a fatal move when working on the exhaust system. Sealants can contain ingredients that will harm the operation of the Catalytic Converter and also damage the Oxygen Sensor.