Skip to main content

Whether you’re buying a new-to-you-car or suspect that someone burgled your existing ride, a missing catalytic converter is a pain in the you-know-what. Your catalytic converter, or “cat,” is a common target for thieves, who can make off with it in minutes. However, it could also be a component your potential used car purchase doesn’t have.

You can tell whether your car still has a catalytic converter with an inspection or by listening for an uncharacteristic sound from your vehicle

  • Listen for increased loudness and excessive noise with throttle
  • If you notice an increase in fumes, you might be missing your catalytic converter
  • Perform an inspection under your car for a missing converter

You slide into your car’s cabin one morning, turn your ignition key, and you flinch. Understandably, you simply weren’t ready for the cacophonous noise coming from your vehicle’s underside. Well, there’s a good chance that crafty thieves cut out your catalytic converter under the cover of darkness. 

The increased noise of startup and throttle are the most common indicators that thieves did the deed. However, if you buy a used car that sounds deceptively loud compared to a stock model, you might have an aftermarket exhaust system that ditched the factory cat. 

Moreover, you may notice an increase in exhaust fumes and odors. That’s from the now-incomplete nature of your exhaust system. After all, a cat is an important part of your factory emissions control system. 

Your catalytic converter is a large portion of your exhaust system. Consequently, you can tell if a thief has cut yours out of your exhaust system with a visual inspection. Ideally, get the car up on a lift safely. Then trace the exhaust back from the manifold or header, or the portion closest to the engine block. 

Move back toward the mid-pipe and rear of the car. There should be a thicker, typically ribbed portion. That’s your catalytic converter. Conversely, if there is a gap in your exhaust system there, your cat is missing.

However, many vehicle owners install components like catless downpipes and straight-pipe systems that eliminate a cat. As a result, your modified car purchase might not have a cat at all. If you can coexist with the added volume and tone of the aftermarket system, it shouldn’t be a problem. Still, if you live in a state like California, your vehicle might not pass emissions testing.

Best in Tips, Tricks & Trends
Avatar photo
Staff Writer

Erik Sherman

Erik Sherman joined the MotorBiscuit team as an Autos Writer in 2022. An admitted petrolhead and an avid motorcyclist, Erik has owned everything from classic cars to motorcycles to modern driver’s cars. Erik also has extensive experience with military and emergency vehicles, ranging from ambulances and fire engines to MRAPs and M-ATVs. Erik is an eager car and motorcycle reviewer with experience covering everything from sports cars to pontoon boats and jet skis.

Erik holds a Bachelor’s Degree in International Relations (IRG) from the University of Texas at Austin and has studied Chinese, Energy, and European Politics at the University of Glasgow in Scotland. Erik’s background is unorthodox; he is a United States Marine Corps (USMC) combat veteran, water survival practitioner, and a former firefighter/EMT. Additionally, Erik is a regular volunteer and former instructor with the American Red Cross (ARC).