Catalytic Converters: 5 Things Every Driver Should Know (Before It’s Too Late)

Most drivers never think about their catalytic converter (aka CAT) until the check engine light blinks, their car smells like rotten eggs, or a thief with a Sawzall makes off with it. Let’s fix that. Here are five questions we hear all the time – answered by the engineering team that’s been keeping engines happy for over a century.

1. What exactly does a catalytic converter do?

We’re not going to get super-nerdy on you. Your CAT is basically an exhaust scrubber. As fumes pass through, it transforms nasty gases – carbon monoxide, hydrocarbons, nitrogen oxides – into much more benign stuff: carbon dioxide, nitrogen, and water vapor. Cleaner tailpipe, cleaner air.

2. What can go wrong with it?

Plenty. Because the CAT sits under your car, it’s a sitting duck for road debris, potholes, and curbs. Engine misfires or injector issues can cause carbon buildup that clogs the converter. Oil or coolant leaks can coat its internals, which means expensive replacement – and by expensive, we mean expensive. Total CAT replacement costs run $2,123 to $2,459+ on average, according to RepairPal using current 2025 data.

3. Why are catalytic converters such a hot target for thieves?

Two words: precious metals. Your CAT contains platinum, palladium, and rhodium – materials worth hundreds on the scrap market. SUVs and trucks are especially tempting because thieves can slide under and slice them off in under a minute. Protect yours by engraving it, parking smart, or installing an anti-theft device or vibration-sensing alarm.

4. How do you know if your CAT is failing?

Your car will yell at you in multiple ways:

• Check Engine Light: Codes like P0420 or P0430 are common.
• Smells & Sounds: Rotten egg odor or rattling when driving.
• Performance Drops: Failing emissions, worse fuel economy, sluggish acceleration, overheating, or rough power delivery.

5. How do you keep your CAT healthy (and your wallet happy)?

• Stick to your vehicle’s maintenance schedule.
• Don’t ignore that check engine light.
• Use quality fuel and don’t only drive short trips – your exhaust system needs heat cycles.

Clean your emissions system regularly. Every 5,000 miles, use Rislone Cat Complete® Fuel, Exhaust & Emissions System Cleaner (part #4720). It scrubs away carbon, soot, and oily residue, clears common OBD codes, turns off check engine lights, saves gas, and is guaranteed to help your vehicle pass emissions testing. Just pour it into your gas tank and drive – no tools, no shop visit. Use every 3-4 months and never have a problem with your CAT again.

“Paying attention to the signs of trouble can be the difference between a $30 cleaning and a $3,000 replacement,” says Clay Parks, our VP of Development.

The Bottom Line

Your catalytic converter quietly saves the planet – and your lungs – every mile you drive. Treat it well, and you’ll avoid headaches, failed emissions tests, and giant repair bills.

Rislone has been helping drivers protect their vehicles for over 100 years. All of our products are made in the USA, ISO 9001 certified, and available wherever quality auto parts are sold.