Can I replace a stolen catalytic converter with a straight pipe?

Due to the high repair costs of replacing a stolen catalytic converter, you might be wondering, can I install a straight pipe and avoid the costly replacement of a new one?

Can I install something quick so I can drive my car without it sounding like a 747 jet airliner?

The short answer is yes you can. However, it is illegal.

If you install a straight pipe, often called a test pipe, you will fail all emissions tests or smog checks. This is because a catalytic converter’s primary job is to convert dangerous emissions (like carbon monoxide) from gasoline-fueled engines into more environmental-friendly gases, like carbon dioxide or water vapor.

Because catalytic converters contain precious metals, they are often targeted by thieves who can cut out and remove a catalytic converter in just a few minutes. Catalytic converter theft has seen a drastic increase in the past few years due to the price increase of rare metals that are in many catalytic converters.

Thieves simply jack up your vehicle, cut it away from the exhaust pipe, and off they go. You can learn more about catalytic converter theft here.

Even if you don’t care about passing emissions checks, or live in a state where an emission test is not required, removing a catalytic converter from your exhaust system is illegal in all 50 U.S. states.

Additionally, should you need muffler or exhaust work done in the future, most reputable mechanics won’t touch it unless they are putting a new catalytic converter back on the vehicle.

And, you can forget about trading in your car, truck or SUV, because you won’t be able to sell it or trade it in unless you find a 3rd party buyer willing to take it.

Won’t thieves just steal my new catalytic converter?

And that is where the dilemma lies. It would be awful to replace a stolen catalytic converter with a new one only to have it stolen again. Catalytic converters are expensive to replace. Especially if you don’t have comprehensive insurance on your vehicle.

This is especially true if you own a popular vehicle like many hybrids or low emissions vehicles such as the Toyota Prius.

Once a thief has stolen a catalytic converter from you, they know you are more than likely going to replace it, making you a prime target for a second theft of the new one.

What happens if I do replace my catalytic converter with a straight pipe or test pipe?

A straight pipe or test pipe is used to bypass a catalytic converter on a vehicle. A test pipe is simply a piece of exhaust pipe that is welded or attached where the catalytic converter used to exist.

The main reason people consider installing them is the potential gains in performance. Because engine back pressure is reduced, the gases can flow freely which increases engine performance or horsepower.

Installing one usually requires reprogramming your engine’s computer so you can adjust the oxygen levels so the check engine light doesn’t keep coming on and your engine operates efficiently. Often when a catalytic converter is stolen, some car’s computers will go into a limp home mode where the car’s computer system detects an issue that could damage the engine and thus turns off non-essential features in order to prevent damage. Fuel efficiency is another issue.

Can I temporarily replace my stolen cat with a straight pipe until I get my car fixed?

You can, but you will likely have some performance issues, and the check engine light will remain on. If the catalytic converter has been stolen, chances are the oxygen sensors were damaged as well since they lie in proximity to the converter.

These sensors are used by the onboard computer to ensure a good mix of fuel and oxygen. They measure the amount of oxygen present in the exhaust system to ensure that the engine’s computer is mixing the correct air-to-fuel ratio for the engine so your car runs properly.

Having an oxygen sensor ensures proper fuel consumption and that your engine is operating efficiently.

It is recommended that you avoid driving your car until the catalytic converter has been replaced or a temporary test pipe installed. Removing the exhaust system from a car or driving with a partial exhaust system can damage the engine over time.

And it will be loud as hell.

If you need to drive the car a short distance for repair, then you will most likely be fine.

What should I do instead?

If possible, you should replace your catalytic converter with an emissions-compliant cat based on the laws of your state.

However, keep in mind that in all but the strictest states (New York, California, etc), you do not need to install a manufacturer’s OEM catalytic converter. Many aftermarket catalytic converters can do the job at a fraction of the cost.

Your local muffler shop can advise you on the best catalytic converter for your car and in most cases, you can get your converter replaced for under $1000. This is nearly half the cost of the nationwide average of $2100.

How can I protect my car from having my cat converter stolen again?

Prevention is the best approach. Keep your car in the garage if you can, or at least in a well-lit area. You can attach Catalytic converter shields, catalytic converter cages, or etch and paint your catalytic converter so it is harder for thieves to resale to scrap dealers and metal recyclers.

Amazon and other retailers often carry them for different vehicle models. If not, call the local exhaust shop which may be able to fabricate something for you that is customized to your vehicle.