What does a catalytic converter do, and can it be cleaned?

As part of a car’s exhaust system, a catalytic converter contains some pretty exotic metals that help convert the engine’s exhaust gasses to less harmful chemicals. It’s pretty high-end chemistry, but the converter’s job is to make the overall exhaust emissions less harmful to people and the environment.

Several things can go wrong with a catalytic converter that can stop it doing this job, and that’s when the dashboard light will flash on, alerting you to the fact that the converter needs attention.

Sometimes, the converter’s internal structure (the matrix) will collapse, at which point the only solution is to replace the unit. But sometimes, the matrix simply gets clogged by soot and other contaminants from the engine’s combustion process. In the case of the latter, you can remove the converter and manually clean it or, add a chemical to the car’s fuel tank that will be burnt in the engine, pass through the converter and hopefully clean it.

However, the jury is still out on whether using either method to clean a catalytic converter is worth the time and effort. Many cleaning attempts have led to the dashboard light flickering back on within minutes of the cleaning taking place. Perhaps the additive method is worth a try, but in a high percentage of cases, converter replacement is the only fix. So why not just remove the converter? Because it’s illegal to tamper with a car’s emissions control devices and there are big fines for those who do so. Also, a catalytic-converter warning light on the dashboard is actually a roadworthy item.