Rats who steal CATs

Catalytic converters have been in the news lately, prompted by videos of some outrageously brazen thefts posted online. 

Catalytic converters have been fitted to petrol cars since the 1990s and to diesels since about 2001. They look a bit like an extra silencer fitted into the exhaust, where the catalysts instigate chemical reactions in the exhaust gas to get rid a lot of the harmful pollutants. 

A catalyst is a substance which makes other chemical react without being affected itself and for cars, the substances are precious metals; platinum is the one most of us are familiar with, but rhodium and palladium are also used. 

Like any commodity, precious metals rise and fall in price and at the moment the price is very high. The resulting potential rewards for scrap metals makes the scum on the fringes of society feel it’s OK to steal the catalytic converter (usually known as the CAT) from other people’s cars and sell them to equally anti-social scrap metal dealers.

Unfortunately, stealing CATs is not hard, otherwise the imbeciles stealing them wouldn’t figure out how to do it. They simply dive under the vehicle and use powered shears or a grinder to cut through the exhaust pipe either side of the CAT. The owner is then left with the inconvenience and cost of getting the car repaired. 

There have been suggestions in the press that owners might not realize the CAT has been stolen, rendering them liable to a fine of up to £1,000, but this is not likely. A loud exhaust noise will be obvious as soon as the engine is started - like a large motorbike or an express train. Most owners will realise straight away that something is wrong. The engine warning light will also stay illuminated in the dashboard.

Typically, a replacement CAT will cost somewhere between £300 and £500, but there could be two if the engine is a V4 or V6. Then the damage to the exhaust pipe will have to be repaired and the new CAT fitted. If you have comprehensive insurance it should cover this theft, but there is always the excess to pay and weighing up whether making a claim will simply boost your premiums next year.

There are some things we can do to deter theft; park in a garage if possible, although I accept that’s not an option for many city dwellers. Parking under a street light or in a busy road may help. 

CAT protectors are available which clamp round the unit and attach it to the underside of the vehicle with a strong wire rope. They are a deterrent because at the very least they will take a lot longer to cut through, but they cost around £100 - £150. 

Ask a garage to mark the CAT indelibly so it can be traced – engraving the car’s number plate or VIN will help the police prove the CAT has been stolen if a scrap metal dealer is raided; otherwise there are no distinguishing marks and thieves or scrap dealers can claim they come from scrapped cars. 

Manufacturers could also give some thought to the design of the exhaust; some vehicles have the CAT fitted in the engine bay where they are very difficult to access from underneath whereas others are child’s play to get at.

Vehicles with a high ground clearance are the most susceptible, because they don’t have to be jacked up to get underneath, so vans and 4x4 cars are more at risk, although one recent post showed a completely shameless criminal blocking the traffic while he jacked a car up, cut the CAT out of the exhaust and calmly walked back to his car. His number plate is clearly visible, so hopefully the police have paid a visit.

Finally, if you see someone working suspiciously under a car, don’t get directly involved; the thief is a thug with no conscience and a heavy tool in his hand, but do call the police and report it as soon as you can.  If you’ve got dashcam footage of the theft, so much the better.

By Tim Shallcross, IAM RoadSmart head of technical policy