DPF and catalytic converter: essential points to check before mounting

Has a customer asked you to replace their car's diesel particulate filter or catalytic converter ? This is a relatively common and necessary operation when an anti-pollution device gives up the ghost. To ensure that the replacement of the catalytic converter or DPF goes as smoothly as possible, we have compiled some essential checks to be carried out before fitting new equipment.

Identify the source of the fault

To begin with, we recommend that you understand the source of the catalyst or diesel particulate filter fault. In the case of DPF, it is often clogging that is responsible for the malfunction.

In the case of catalytic converters, it can sometimes be a question of the ceramic breaking down as a result of repeated thermal shock. It's a fact: many motorists choose diesel-powered vehicles for predominantly urban use. The result is rapid clogging, which can make it necessary to replace the DPF.

Before carrying out the operation, it is therefore necessary to identify the cause of the fault to prevent it recurring. Often, a component in the exhaust line can cause problems with the DPF or the catalytic converter.

The testing stages involved

As we know, exhaust gases are very harmful. They must therefore be able to circulate optimally in order to reduce their pollutant content and allow them to be converted into carbon dioxide (CO2). Let's take a look at the various elements that need to be checked before fitting a new DPF or catalytic converter to customer vehicles.

• Differential pressure sensors: these detect a difference in pressure between the inlet and outlet of the DPF. Without these sensors, regeneration would not be optimal and could lead to rapid clogging. It is essential to check and replace these sensors if necessary;
• Temperature sensors: these measure the temperature of the exhaust gases to detect any saturation of the DPF. They also trigger regeneration cycles when necessary;
• The EGR valve: this recirculates exhaust gases, limiting NOx emissions. It is essential that it is in good working order, otherwise the new DPF will wear out prematurely;
• Injectors: often overlooked, injectors are essential to the smooth running of an engine. They ensure good combustion and can limit pollutant emissions. A check of the injectors is therefore essential before replacing a catalytic converter or diesel particulate filter;
• Glow plugs: like injectors, glow plugs help to reduce the pollution emitted when diesel cars start up. Check that they are in good condition before starting work. Without them, the DPF may clog up more quickly, reducing the life of the new equipment;
• The engine thermostat: to reduce pollutant emissions, you also need to ensure that the thermostat is in good working order. It regulates engine temperature by adjusting the injection of coolant;
• The intake manifold flap actuator: sometimes forgotten, this actuator controls the volume of clean air injected into the engine. It therefore has a major impact on pollutant emissions. It should therefore be checked regularly and before replacing a catalytic converter or diesel particulate filter;
• The intake pipe: a clogged intake restricts the flow of air, which can unbalance the stoichiometric ratio, increasing pollutant emissions and fouling the new DPF more quickly;
• The upstream catalytic converter: if you're replacing the DPF, make sure you take the time to check that the catalytic converter is in good condition. Many people recommend replacing both components at the same time. If it's a monobloc, it's even recommended;
• Engine oil: a recent engine oil will help prevent clogging. You should therefore strongly recommend that your customers change their engine oil as soon as possible if it has exceeded the recommended intervals;
• The DPF additive system: if your customer's car uses an additive designed to lower the temperature at which regeneration cycles are triggered. In the case of the former PSA entity, this is cerine. This additive also needs to be checked for proper filling.

Tedious but necessary steps

These checks are naturally time-consuming, but they are essential. A successful diesel particulate filter or catalytic converter installation is first and foremost the result of a careful check, which will ensure that your customers have a long-lasting, high-quality installation.

As for the fitting operation itself, don't forget to disconnect the battery, carefully remove the various sensors and ensure that the exhaust system is perfectly sealed. If this is your first DPF replacement, don't forget to use a diagnostic kit to indicate the replacement. Otherwise, there is a high risk of malfunction.

It's also advisable to take the time to inform customers about the basic operation of a diesel particulate filter and the need to drive long enough to trigger regeneration cycles. Proper use of a diesel engine greatly reduces wear and tear on a diesel particulate filter.

Sometimes, the problem of replacement can also put some motorists off. It's true that this represents a major expense, if only in terms of labour. If other components are due to be replaced in the near future, it may be worth taking advantage of the dismantling/assembly of the new system to avoid having to reassemble it at a later date.

Things to remember

Before fitting a new anti-pollution device, it is essential to carry out a thorough examination of the damaged part. You need to take the time to understand the cause of the fault to avoid it recurring.

A faulty ancillary part may have damaged the diesel particulate filter prematurely. Failure to resolve the problem may result in premature damage to the new diesel particulate filter.

So it's best to prevent any ignition problems, sensor failures or even oil leaking into the exhaust system. Your customers will be grateful to you for identifying the fault and preventing it from happening again.

Finally, Krosfou diesel particulate filters and catalytic converters are supplied with installation instructions. We recommend that you consult it for any special features relating to the new equipment. The installation guide also covers the various practical aspects you need to be aware of.

You are now ready to replace the diesel particulate filters on your customers' vehicles. This type of operation is set to become more widespread, as all diesel-powered cars have been fitted with them since 2011. We therefore advise you to adopt the right habits for quality interventions that will delight your customers.

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Karolina Osinska / Author: ADDICTIVE_STOCK / Licence ID: EZMFT5BCV9 - elements.envato.com