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We tested five universal catalytic-converter anti-theft devices that guard against the new wave of cat burglars.

Just the words "catalytic converter theft" can make car owners shudder. It's a highly inconvenient issue that's on the rise due to the valuable metals within these critical emissions-control devices. As the material prices have increased, theft has become a problem that has everyone from your average Joe to luxury-car owners turning their heads at the increasingly familiar sound of an unmuffled engine.

Enter the world of catalytic-converter protection and alarm systems, a booming industry that has arisen in response to the high-stakes scavenger hunts. Combining the latest detection technology with heavy-duty, vehicle-specific shielding, these systems are stepping up to combat the catalyst burglars on a new front.

Take a peek as we dive into the nuances of the top universal devices that strive to protect your vehicle in the fight against catalytic-converter theft.

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The need for protective measures has become more evident in recent years, as statistics show a significant surge in catalytic converter thefts. According to insurance claims data, thefts of catalytic converters increased fourfold over three years—from 16,660 claims in 2020 to 64,701 claims in 2022. This alarming rise shows the importance of a robust security solution so you don't fall victim to this lucrative crime wave.

Specific models, especially hybrids and those with higher ground clearance, are more attractive targets for thieves and might require more robust protection systems.

Related: 10 Cars Catalytic Converter Thieves Target Most

Physical barriers such as steel plates and cages aim to deny easy access to the catalytic converter. Alarm systems, meanwhile, serve to scare off potential thieves or alert you when tampering is detected. For comprehensive security, a combination of both physical and alarm-based protection might be the best approach. It's not that these devices make it impossible to steal your catalytic converter, but may be enough deterrent to send the crook looking for an easier target.

Some protection devices are DIY-friendly, while others may necessitate professional assistance. Understanding what your chosen system demands in terms of installation is vital before making your purchase.

A substandard shield or an unreliable alarm system can do more harm than good, offering a false sense of security while failing to provide adequate protection. Do your research on devices and manufacturers before purchasing a catalytic-converter anti-theft device.

While protecting your vehicle is essential, that protection shouldn't outweigh the cost of replacing the converter itself. Find the right balance between cost and security, considering that preventive measures often prove cheaper than repairs or replacements.

Catalytic-converter anti-theft devices are designed to do one thing: Stop folks from stealing your catalytic converter. So why not try to steal our own catalytic converter? We put our rusty yet trusty Mitsubishi Eclipse onto ramps, installed each product, and evaluated the following parameters:

InstallationFor a simple and intuitive installation, the Catstrap is a great choice. Picture it like ketchup on a hot dog—a rugged yet flexible orange warning strap that runs along the length of the exhaust system. It's secured by four clamps—two at each end of the converter and two at each strap end—and then stainless-steel zip ties in between.

As a unique final layer of security, the back side of the strap features heat-activated adhesive that sticks to the hot exhaust system while you drive. (Note: We did not heat up our exhaust prior to testing.)

Of all the products we tested, the Catstrap proved the easiest to set up. Installation took a mere five minutes with two people working together.

Robbery Attempt

While the bright-orange exterior was quick to tear, CatStrap's real defense mechanism is the three layers of hardened steel strips beneath. The strips repelled the Sawzall blade, offering significant resistance against the tool. Adding to the challenge, we were on our backs and cutting "up" onto the exhaust, leaving us fatigued. After three minutes of struggling, we paused to inspect, only to find a tiny gouge on the Catstrap innards.

Curious about our angle of approach, we decided to uninstall the strap and cut it in half in a vise from a different angle. Even from another angle and detached from an exhaust system, the Catstrap remained impenetrable.

Overall, the combination of an orange exterior, heat-activated adhesive, and hardened steel strips created the ultimate trifecta of protection. The Catstrap is bright, it adheres firmly to the exhaust, and it's incredibly tough to cut. With the Catstrap installed, even the boldest of thieves would surely think twice.

Installation

The CatClamp is an excellent choice if your vehicle has a large, easily accessible chassis. Its installation harks back to a simpler time, using a single steel cable between two discs resembling handcuffs, which are further connected into four anchoring points on your vehicle's chassis. The steel-on-steel design results in a steampunk-esque spiderweb, with your catalytic converter, like trapped prey, at the center of the tangle.

While installation is straightforward, we think the device is best paired with a large vehicle. Installation on our compact Mitsubishi Eclipse posed some challenges, notably during the first step of fitting the steel discs between the exhaust and the floorpan. Ultimately, we had to remove a few exhaust hangers to make room. While this is not a significant roadblock, it's unlikely to be a problem on a larger vehicle.

Robbery Attempt

To remove a catalytic converter with the CatClamp installed, you must first cut through four points along the steel cable. Attempting to cut even one portion of the cable revealed the intended effect: The Sawzall simply can't handle loose steel cables. The braided steel cables and the slight slack caused the blade to dance along the surface, rendering it unable to gain traction and penetrate the material.

The CatClamp defenses were so effective that we had to abandon our parameter of "How long does it take to remove this device?" since, well, after several minutes we couldn't do it. While we may not be experts in the art of stealing catalytic converters, we doubt a competent thief would spend more than a minute or two trying to get through the CatClamp. We think the CatClamp, with its formidable steel design and impervious defense system, is a great product to protect your valuable asset.

Installation

The Cat-Rap shares many qualities with the CatClamp, such as steel cables and frame-rail weaving. However, it stands out thanks to its cleverly designed steel-plate system, which is held together by 11 head bolts and positioned at the converter's bottom side.

In the Cat-Rap system, two steel cables intertwine around the catalytic converter, passing through the unique steel-plate locking mechanism. The installation process is remarkably ordered: "Wrap once, move through the next bollard, and repeat," ensuring a smooth and accurate setup.

As the installation nears completion, each cable is wrapped around the vehicle's chassis, leaving some slack before making one final weave into the steel plates. The next steps are tightening the plate bolts and installing a shield for added security. This shield effectively locks down the unit, safeguarding the tightening bolts from any determined thieves equipped with the right socket and wrench.

Robbery Attempt

Again, the Cat-Rap and the CatClamp share many qualities in their materials, presentation, and effectiveness as theft deterrents. While the CatRap has notably thinner steel cables, the effect is the same: a blend of braided steel and a little slack causes the Sawzall to recoil.

During our Sawzall test, we found no success in removal. The striking similarities between the two steel-cable designs make it difficult to distinguish their removal process. Trust us, anyone attempting to steal your catalytic converter with the Cat-Rap installed will wind up confused and frustrated, and likely move on.

Installation

If you're looking for effective mediocrity at an affordable price, you might consider purchasing the Sparkwhiz. The Sparkwhiz is a simple battery-powered alarm that attaches to your catalytic converter with thin cables, steel zip ties, and a heat-activated exhaust sticker. Arm it manually with a fob, and the alarm detects vibrations on your exhaust system.

Although the Sparkwhiz didn't come with detailed installation directions, we figured out how to secure it to the catalytic converter with the various attachments provided. We got the alarm running in less than five minutes.

Robbery Attempt

Surprisingly, a mere tap on the exhaust system activates the ultrasensitive SparkWhiz, setting off its shrill alarm. As testers Collin Morgan and Gannon Burgett braved the activation under the vehicle, they were bombarded with a manufacturer-claimed 113-decibel blast. From our 10-foot observation point, we clocked it at a lower 90 decibels, but that should still be plenty to stand out from even loud city traffic.

Ultimately, we felt the SparkWhiz's alarm may be better at scaring away the thief under the vehicle, rather than alerting a far-away owner, but that could be enough.

Installation

Catstrap has extended its anti-theft offering into alarms, with its Cateye Electronic Alarm. The two alarms featured here operate in distinct ways.

The Cateye, for instance, is hard-wired to your vehicle's battery, providing constant power to the controller box. The controller box is connected to a sensor positioned beneath your vehicle to detect movement.

During our tests, we encountered some installation challenges, primarily around the placement of the controller box. Catstrap suggests installing it along the firewall of your engine bay (to prevent water exposure). However, this posed an issue for our compact Eclipse, as there was limited space in the engine bay, making long-term installation difficult or even impossible. Potential buyers should assess their engine bay before purchasing to avoid similar issues.

Another perplexing aspect of the installation was determining the exact location of the sensor. Since the sensor uses infrared light to detect motion, it could be vulnerable to false alarms triggered by wildlife or passersby. Though CatStrap recommends placing the sensor at the front of the vehicle looking toward the rear, we learned that finding the right spot required some experimentation. Eventually, we landed on a heat-shield location that looked toward the catalytic converter and provided reasonably accurate motion sensing.

Robbery Attempt

Activation of the Cateye depends on the sensor location. In our case, the alarm did not trigger until the saw was close to the exhaust, and simply rolling beneath the vehicle did not activate it.

The recorded ear-piercing noise from our 10-foot testing distance reached 110 decibels, described as "unbearably loud" from under the car. (Thankfully, our testing team wore hearing PPE.) The Cateye appears to be designed to make your robber want to be anywhere but beneath your car. To that end, it is effective.

However, we discovered a potential weakness in the Cateye. A pair of cutting pliers can disable the hard-wired alarm, rendering it useless. While it's unlikely that someone would endure soul-penetrating shrieks to find the right place to snip, it's a critical point to consider. For a robust defense, why not consider both Catstrap products?

Sight

On most vehicles, you won't notice a catalytic converter has been stolen just by looking from the outside. If you suspect your catalytic converter has been stolen, checking beneath your car is the best way to verify. If your catalytic converter has been stolen, you will notice an altered exhaust system: a pipe or set of pipes that run the length of your vehicle will have an empty space where the catalytic converter should be.

Sound

If your catalytic converter has been stolen, your vehicle's exhaust system will produce a loud rumbling or roaring sound. That's the sound of your unmuffled engine blaring.

Smell

Without a catalytic converter, your engine's exhaust is pouring out almost immediately after combustion. If your converter has been stolen, you'll likely smell exhaust or a sulfur-like odor in or around your running vehicle.

When working with vehicles, necessary precautions should always be taken. Take special care with the following:

Avoid Crushing

To install your anti-theft device, you will likely need to lift your vehicle. If you're using a jack, support the vehicle on jack stands in case of jack failure.

Avoid Burns

Exhaust systems get extremely hot. Protect your skin from serious damage by installing your device after your vehicle's engine has been off for several hours.

Avoid the Driveshaft and Other Moving Parts

In the case of our Mitsubishi Eclipse, the driveshaft and exhaust system are very close. Take care to install your anti-theft devices (most notably steel cables) far away from moving components.

Know Your Vehicle

While all of these installations can be completed with simple tools and time, they require general knowledge of the underbelly of your vehicle.

Grab a Buddy

While this isn't required, we noticed things went much smoother with two sets of hands. So make a day of it—help install a friend's anti-theft device and swap cars for another round.

Report the Crime to the Police

Sadly, it is unlikely the police will recover your catalytic converter. However, a police report will be useful for insurance purposes.

Contact Your Insurance Company

Notifying your insurance company should be next on your list. If you have comprehensive coverage, you may be eligible for compensation. But don't count on it—with thefts on the rise, insurance companies are quietly bowing out of this type of coverage.

Inspect Your Vehicle for Additional Damage

A sloppy thief can cause real damage to a vehicle. Check under the vehicle for damage, most notably brake and fuel lines. After an incident, take comprehensive photos of the condition of your vehicle, as this could be useful for insurance claims and repairs.

Repair Your Vehicle

Once your catalytic converter has been stolen, you will want to replace it quickly. For one, a missing catalytic converter will immediately throw on the anxiety-inducing check-engine light. Second, the engine will be loud and emit noxious exhaust fumes into your cabin. Lastly, a vehicle with a missing cat converter will not pass a smog check.

Look Into Additional Security Measures

Investing in theft deterrents is your best bet against another catalytic-converter theft. Luckily, we just tested five great options for you.

Tell Your Neighbors and Friends

Raising awareness helps the community remain up to speed and could prevent further thefts.

Considering that catalytic-converter anti-theft devices are designed to mitigate theft, we figured the best way to pursue our test was to try to steal one. So we did just that.

To get a clear idea of how long it would take to steal a catalytic converter, we simulated an exhaust system on our workbench. Hanging a 2.5-inch exhaust pipe from a series of rubber hangers, we used our shop Sawzall (with metal-grade saws) to determine a baseline (47.3 seconds for two cuts—impressive!). This baseline demonstrates how quickly thieves can get away with your catalytic converter.

Afterward, we rolled in and lifted our trusty Mitsubishi Eclipse onto a set of QuickJacks. With our vehicle lifted to a modest but manageable height, we installed each product onto its exhaust system, assessing its features and ease of installation.

Leaving the Eclipse on the jacks, the remainder of our test was essentially cat-burglar cosplay, attempting to assess the products from the perspective of someone trying to steal the catalytic converter.

First, we visually inspected the installed products, noting any visual deterrents that would sway someone from an attempted theft. Next, we attempted to remove the devices using our shop's reciprocating saw and metal-grade blades. We had originally intended to measure the time it took to remove them; however, we found the physical shield devices remarkably effective, leaving us to abandon that parameter altogether. Let's just say, they're effective.

Lastly, for the alarms, we measured sound level in decibels from a 10-foot distance.

What is a catalytic converter, and why is it a target for theft?

A catalytic converter is a critical part of your car's exhaust system that helps reduce harmful emissions. This valuable car part contains precious metals like platinum, palladium, and rhodium, which makes it a hot commodity for thieves. A stolen catalytic converter can fetch a good price on the black market, hence the rising cases of catalytic-converter theft.

How does a catalytic-converter protection system work?

A catalytic-converter protection system usually comes as a physical shield made from high-quality, durable metal that's secured around the converter, making it a tough nut to crack for potential thieves. It's like fortifying your car's underbelly with a suit of armor— unsightly, but a worthwhile deterrent against theft.

What's an alarm system for catalytic converters, and how effective is it?

Catalytic-converter alarm systems are electronic devices designed to alert you when a theft attempt is detected. They use sensors to monitor vibrations, heat, or even the presence of a person underneath your car, and they trigger a loud alarm to scare off potential thieves. The effectiveness varies by model and installation, but they can be a worthwhile investment, especially if you live in an area with high catalytic-converter theft rates.

Do I need both a protection system and an alarm system?

While not strictly necessary, employing both systems provides a comprehensive approach to securing your catalytic converter. Think of it as a one-two punch: the protection system acts as a deterrent, and the alarm system alerts you if a determined thief tries to get past that initial defense. But your choice should reflect your circumstances, such as local theft rates and personal risk tolerance.

Is there a specific type of vehicle that's more prone to catalytic-converter theft?

Yes. Vehicles that sit higher off the ground—such as trucks, SUVs, and vans—are more susceptible simply because the catalytic converter is easier to access. However, don't assume your low-slung sports car is safe, as seasoned thieves have ways to get under even the lowest ride.

What other measures can I take to protect my catalytic converter?

Besides a physical shield or alarm, you can take other measures such as parking in well-lit areas, using a garage when available, and having your vehicle's VIN etched onto the converter. Increasing the risk and difficulty for thieves can significantly reduce the likelihood of your converter being stolen. The best defense is a multilayered one.

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Hearst Autos combines the talent, resources, and expertise of three of the largest, most influential automotive publications in the world. The Gear Team has tested a wide variety of automotive products, parts, accessories, and gear, such as garage flooring, wet-dry vacuums, and electric car charging equipment. We get our hands on each and every product we test. Most are purchased; some are supplied by manufacturers.

Hearst Autos doesn't need to game algorithms for traffic or promote lousy products to earn a buck. Instead, we're more concerned with our legacy, our reputation, and the trust that our readers have in Autoweek, Car and Driver, and Road & Track to deliver honest opinions and expert evaluations.

Visit our Tested & Trusted page to see the very best in automotive gear. Read more about our product testing and evaluation process here.

Katherine Keeler is an Assistant Testing Editor at Hearst Autos. By day she evaluates tools for your enjoyment; by night, she Frankenstein’s her ever changing fleet of rust-bucket-oddities back to repair. Her dream is to open a roadside attraction where the public can view, drive, and learn repairs at her emporium of curious cars.

Gannon Burgett loves cameras, cars, and coffee: a perfect combination for his Hearst Autos work. His byline has appeared in USA Today, Gizmodo, TechCrunch, Digital Trends, the Detroit Free Press, and more.

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