Buying used catalytic converters: Factors to consider and associated risks

For some years now, we've been witnessing an increase in the price of car parts. This puts a heavy burden on motorists' wallets. When a car's catalytic converter breaks down, it has to be replaced as quickly as possible to avoid more serious mechanical problems. It can be tempting to go for a second-hand model. After all, a catalytic converter has a fairly long service life. But is it really a good idea ? We have a very clear opinion on the subject..

A second-hand catalytic converter: a good idea ?

Basically, the lifespan of a car catalytic converter is quite substantial. It can approach 150,000 kilometres and sometimes even much more. The more often a car is driven and the longer the journeys, the longer the life of the catalytic converter. It may therefore be tempting to buy a second-hand model, in order to save money.

A good number of cars are scrapped every year, often because the engine is out of action, the bodywork is too damaged or the repair costs are too high... Rarely because the catalytic converter has deteriorated.

Although the temptation is strong and the savings real, it is not really advisable to choose a second-hand catalytic converter for your car. The risks are considerable, and above all you run the risk of rapidly losing efficiency and sometimes even damaging your car's engine to a greater or lesser extent.

How can you be sure that a catalytic converter is in good condition ?

Unfortunately, it's very difficult to know how healthy a catalytic converter really is. When you choose a second-hand model, you can't be sure how long it will last.

Over the course of many kilometres, the catalytic converter loses its effectiveness. It carries out fewer chemical transformations, but still allows exhaust gases to circulate more or less freely. And because the catalytic converter is a steel cylinder, it cannot be opened to check its internal structure.

Choosing a second-hand model therefore means you can't estimate how many years it will have left to live. As a result, your equipment could give up the ghost the very next day... or ten years later!

The catalytic converter also has a number of peripheral components that have a major impact on its efficiency. This is particularly true of lambda sensors.

These are used to take measurements. If they are altered, the engine may run too lean or too rich, which could cause premature damage to the catalytic converter. As you can see, choosing a second-hand catalytic converter is no mean feat.

Is it easy to replace a catalytic converter ?

Replacing a car catalytic converter is not a very complicated task, but you need to be meticulous and have the right equipment to carry out the operation safely . In fact,we've put together a guide that details the steps, one by one, involved in fitting a new catalytic converter to a car. Before taking the plunge, it's imperative that you familiarise yourself with the procedure so as to be able to anticipate any difficulties that may arise. Now more than ever, you need to look after your own safety, because a catalytic converter is a fairly heavy piece of equipment, and you need to be able to handle it without risking danger.

What should you check ?

Before buying a second-hand catalytic converter, you need to make sure that it is perfectly compatible with your car. It must have been fitted to the same model, with the same engine. It's also advisable to obtain as much information as possible about the vehicle from which the catalytic converter was taken.

Ideally, we need to know the type of journey made and, above all, when the catalytic converter was fitted. Is it original equipment or has it been replaced ? In the latter case, it's preferable to have the invoice in order to be sure of the quality.

Similarly, knowing the actual mileage of the second-hand catalytic converter can help determine its remaining life. In practice, a catalytic converter generally lasts between 120 and 150,000 kilometres. But this figure may be much lower for a vehicle that is mainly used in town.

Beware of pollution..

Before buying a second-hand catalytic converter, you need to consider the pollution issue. As a reminder, the purpose of a catalytic converter is to neutralise some of the pollutants leaving the engine. Through chemical reactions, it transforms certain toxic molecules into carbon dioxide and water.

Tired, this anti-pollution device becomes less effective and lets more pollutants through. The direct consequence of this is an increase in pollution.

Your engine may not breathe as well, which could lead to increased fuel consumption and reduced performance. Worse still, at the next roadworthiness test, the risk of exceeding pollution limits is even greater.

It's impossible to assess the condition of the equipment. A second-hand catalytic converter generally has no guarantee. Anti-pollution devices are specific to each vehicle and cannot easily be replaced by others.

The theft of catalytic converters, which is unfortunately still fairly widespread, is not aimed at equipping cars... but rather at recovering the few grams of precious metal that are present in the internal structure.

Catalytic converters not always in the best condition !

Secondly, according to various studies, motorists generally drive relatively little per year, around 12,000 to 13,000 kilometres on average. Of course, there's a big difference between those who drive very little and those who drive a lot... These journeys are generally fairly short, which wears out the catalytic converter prematurely. So buying second-hand is not really recommended.

What's more, the purchase price is certainly lower... But you'll have to remove and fit your catalytic converter, as well as buying new lambda probes, an air filter and spark plugs. In the end, the savings you make are fairly small compared with new equipment, which will last much longer.

Contrary to popular belief, the most expensive catalytic converters are not always the best. Many of the big names offer equipment manufactured at knock-down prices, using low-quality materials.

Conclusion

Unsurprisingly, it's not advisable to fit a second-hand catalytic converter to your car. While you may potentially save money at the time of purchase, you will still have to replace certain peripheral components, such as lambda probes. But above all, you'll have no assurance as to the real state of health of the catalytic converter. If you're lucky, you'll buy a perfectly healthy piece of equipment... But in most cases, second-hand catalytic converters are already very tired, especially if they were fitted to a vehicle that mainly travels in town. As a result, you run the risk of having to replace the equipment prematurely. Worse still, the pollution emitted by your car could be significant by the time the engine gets used to this anti-pollution device, which is already a few years old !

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Karolina Osinska / Author: Pressmaster / Licence ID: PZNETKD6B9 - elements.envato.com