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When to cut the cat out?

One of the most searched phrases related to cats is that about when to cut it out. There is nothing wrong about cutting out the cat if you want to replace the old one with a new one. Otherwise, this must not be done and should never be tried as the cat is a compulsory equipment. Without it you car will not pass a MOT test and the driver may receive a ticket during a routine road check.

What is a “cat”?

A cat is a common name for a catalytic converter. How does it work? It reduces the content of noxious chemicals in the exhaust gas. When viewed form the outside it looks like a silencer in the form of a metal can made of chromium or chromium-nickel steel. What is most important about the cat is hidden inside. The interior is formed by a ceramic or metal monolith of a honeycomb structure, coated with several layers: an intermediate one containing aluminium trioxide, an active one with rhodium, platinum or palladium and a sealing one. The more channels inside the monolith the more efficient performance. Design of the catalytic converter has an impact on resistance of exhaust gas flow, mechanical strength, thermal inertia, thermal conductivity, specific surface area and maximum operating temperature.

When should a cat be cut out?

The catalytic converters are cut out most frequently when they become damaged or worn out. As the replacement is quite expensive some people decide to cut it out and weld the housing. Such a decision may bring undesired effects as the car will not pass a MOT test and the driver may receive a ticket for not having the cat during a routine road check if the exhaust gas emission level is measured. Additionally, it may prove very hard or even impossible to cut out the converter in cars equipped with two lambda sensors as the sensors immediately detect the lack of the converter and the engine is switched to emergency mode.

Another reason for cutting a catalytic converter out is the profit-driven intention to sell it or the desire of having a more “aggressive” engine sound. It should be noted that, if the converter is removed the car will not only emit more harmful substances into the atmosphere but it may also consume more fuel. Therefore, it should be well considered if cutting the converter out and driving a car without it turns out profitable.

Is it possible to replace a catalytic converter with little money?

To avoid any risk and keep the converter unremoved you may try to save some money when replacing the converter. Therefore, it is recommended to sell the worn out cat at a collection point. By doing so you can be offered several hundred or even more than one thousand zlotys. Such an amount will definitely not cover the full cost of a new converter but will help you to reduce the cost of the necessary repair.

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