I bought a used car a few weeks ago. Its road tax had expired and it required inspection. The dealer refused to undertake the task, saying it was not within his ambit. I had no choice since I had already paid for the car, so I took it in for inspection. It was then that I was told that the "cat" was missing. Where do I get a "cat"? Also, what is its function as the car seems to be running perfectly? This is another reminder of the risks of buying a car that has an expired road tax.

"Cat" is short for catalytic converter, which looks a little like an exhaust muffler, and is used for treating exhaust gases to render them less harmful.

It is illegal to remove a catalytic converter. Doing so would mean the car is no longer in compliance with the emission standards that it was originally imported with.

You can detect a car without a catalytic converter easily. The exhaust will have a distinctive smell because all the noxious gases pass right through.

So while your car may run smoothly, it is polluting the air.

You will have to source for the exact same catalytic converter that the car originally came with. If you are lucky, you will find a usable one at a scrapyard.

Otherwise, you may need to buy a new one from the car's authorised dealer. With installation charges, the costs could range from $1,500 to $5,000, depending on the make and model.