Signs of a Stolen Catalytic Converter, What to Do When Replacing One, and More

There are a few different signs of a stolen catalytic converter and different ways to fix this problem. Find out why catalytic converters are valuable and how you can reduce the cost of this problem with these tips from our mechanic Sue.

What Is a Catalytic Converter?

Mechanic standing before different types of catalytic converters
1A Auto mechanic Sue before different types of catalytic converters

Catalytic converters have been in cars since the ’60s and ’70s. Basically, they burn up unburned fuel from the engine.

A truck with a V6 or V8 engine will have four catalytic converters. A car with a 4-cylinder engine with have two converters.

What Are Signs That My Catalytic Converter Has Been Stolen?

Loud Rumble Noise at Start-Up

You’ll hear a loud rumbling noise from underneath the vehicle after you start the engine, like shown in the video at the top of this article.

Check Engine Light

You may find a check engine light is on for a code related to the catalytic converter

Broken Exhaust Pipe and Missing Converter

You may also find the converter missing from underneath your vehicle, with a section of the exhaust cut off and missing.

Why Are Catalytic Converters Valuable?

They Are Made of Precious Metals

Catalytic converters are worth a lot due to their materials, like palladium, rhodium, and platinum.

Today due to many technological advancements, aftermarket converters need to perform as well as the ones originally installed by the manufacturer. These include the same precious metals and are just as valuable.

For cars with a 4-cylinder engine, a converter will be off the exhaust manifold. This will not likely be stolen due to its placement near the engine. The catalytic converter that will probably be stolen will be the type where someone can jack up the car and get underneath to cut it free.

What Should I Do If My Catalytic Converter Is Stolen?

General steps to take for a stolen catalytic converter

  1. Jack up the Vehicle and Assess the Damage

    If you have the ability to jack up your car yourself, we recommend you jack up the vehicle with a jack and secure it with jack stands. This way you can take a better look at the exhaust pipe.

  2. Have the Vehicle Towed or Replace the Catalytic Converter Yourself

    If you’re unable to look at the damage from underneath your car, we recommend having it towed to a professional mechanic so they can fix it.

  3. Replace the Catalytic Converter, and Consider Clamping a Pipe at the Flange Area

    You can replace the catalytic converter yourself with the help of our how-to videos. Our mechanics will instruct you on how to replace the parts and you’ll find other repairs specific to different models.

    Video: How to Replace Catalytic Converter 01-05 Honda Civic

    You’ll see a single pipe runs underneath the vehicle at the center that connects to a catalytic converter. At the end of the original catalytic converter is a flange that connects to a flange on an exhaust pipe. The flange area is known to weaken and rust out over time. If the flange area has been cut off or is in too bad of a condition to install a new converter, you may find you need to remove it.

    Sometimes owners will have the flanges removed and have a piece of metal welded in place instead of spending more by replacing an entire catalytic converter or exhaust pipe.

    As our mechanic Sue notes in the video above at 5:35, connecting the replacement pipe with clamps will allow you to replace this section easier in the future if it rots out again. Welding this area means that when the pipe is later worn and needs replacing, the old pipe will not have to be cut down further until an entirely new exhaust pipe and/or converter needs to be installed.

    You may find you need a section of the exhaust pipe welded in addition to replacing the converter if it was cut off. We recommend replacing the converter with a universal style or an aftermarket original equipment (OE) direct-fit style.

  4. It Parts Were Welded, Check the Welding

    If you need a part welded, check the welding. Stainless steel is not easy to weld, but the weld should be straight and smooth.

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Signs of a Stolen Catalytic Converter and What to Do - 1A Auto
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Signs of a Stolen Catalytic Converter and What to Do - 1A Auto
Learn the signs of a stolen catalytic converter and how to fix this problem with these tips from the expert mechanics at 1A Auto
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1A Auto
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