Cat Delete O2 Sensor: Here’s What You Can Do to Bypass It

If you are looking to remove your catalytic converter and O2 sensors, you are probably worried about how to bypass the technology behind them. The popular mod for many car enthusiasts has consequences that are not favorable to the environment and your vehicle. However, many car owners still proceed with it, especially if they always take the car on the track.

Exhaust upgrades highlights

• Commonreasons:technical issues, power boost, delete
• Average prices:$300 - $3,000
• Average waiting time:1 - 9 days
• Common problems:emission test
• DIY mods:possible but quite complicated
• Level of satisfaction:low

Catalytic Converter and O2 Sensors: How Do They Work?

The catalytic converter and O2 sensors are two essential components in an exhaust system that work together to reduce harmful emissions from your car. 

The catalytic converter converts harmful emissions into harmless gases, while an O2 sensor measures the amount of oxygen in the exhaust stream and sends this information to the Electronic Control Unit (ECU). 

Using this information, the computer will adjust the fuel mixture and produce a balanced air-to-fuel ratio to control the vehicle's emissions.

However, a lot of car owners did not like the restrictions brought by the catalytic converter. Inside this pipe is a honeycomb structure that filters the air passing by, affecting the space for air power generated by fuel combustion. This design reduces the performance of the vehicle significantly. Imagine your nose covered by a facemask. This is how the exhaust system releases the gases it produces. Suffocating.

To alleviate this, car enthusiasts modify their cars and try to provide more room for fumes. This part is where catalytic converter deletion takes place.

What is Catalytic Converter Delete?

Catalytic converter deletion is the process of modifying your exhaust system by removing the catalytic converter. Owners do this for different reasons: improving performance, adding more power, improving fuel economy, and more. 

While there are many good reasons a cat con delete is ideal, it is not always the best option. For once, this process can result in long-term damages like reducing your engine's life and the emission of harmful gases.

By doing any of these methods, you are modifying the engineered design of the exhaust system and compromising its function. The engineered design of an exhaust system has gone through years of research and development to become compliant with emissions standards. For this reason, you cannot pass emission tests with a cat con deleted or hollow out. 

Why do Owners Delete the Catalytic Converter?

The common reason owners remove catalytic converters is to tune their engines for racing. So they won't have to provide more space for power generated by fuel combustion.

Next, owners go for a cat delete because they love the raspy sound produced by the unrestricted exhaust pipe. Petrol heads love its liberating sound of burly, rough, and heavy brawn.

Another reason to cat delete is to reduce the heat produced by the stressed engine. Reducing restrictions also means decreasing the workload of the motor during combustion.

The Legality of Cat Delete

When you consider bypassing a catalytic converter, you should be aware of the legality of this procedure in your state. 

While emission tests are not a problem for some car enthusiasts in a few states, you have to comply with emission standards in your locality, especially if you frequently take your car on the road. These emission tests take place yearly. A failing emission test results in penalties, fine, or imprisonment.

A passed emission test is your license to drive on the road because your car releases safe levels of gases in the air. It is your part in the community to take care of the environment by not putting other people at risk because of fumes coming from your car. 

What Happens When the Catalytic Converter Has Been Removed?

• Muffled exhaust

The action would eliminate the muffling effect of the catalytic converter, resulting in much noisier exhaust pipes and engines.

• High toxic gas emissions

It will also eliminate the main function of the catalytic converter, which is to control the car's gas emissions. 

• Check engine light

The ECU takes signals from the O2 sensors, which work closely with the catalytic converter to provide information to the computer. But with the absence of the catalytic converter, your O2 sensor would detect this abnormality in the system, resulting in check engine light alerts.

How to Bypass Cat Delete?

Here's what happens during cat delete:

• First, you will disassemble the exhaust manifold.
• Next, you'd have to unscrew the bolts that hold the cat con to remove it.
• Lastly, you'd have to reassemble the exhaust manifold and replace the cat con with a straight pipe that fits on it.

When cat delete is not an option, owners hollow out the honeycomb from the inside. In this process, owners or builders remove the catalytic converter entirely to give way for the outlet and inlet. This part is where hollowing it out takes place. 

• After uninstalling the catalytic converter, secure it on a workbench facing side up with a bench vise.
• Next, insert a long chisel and aim for the honeycomb pattern inside the cat con. (Put on a respirator mask.)
• Use a hammer to tap the chisel until the honeycomb breaks apart and your catalytic converter hollows out completely.
• After the previous procedure, you can now clean it and reinstall it.

What is an O2 Sensors Bypass?

Bypassing O2 sensors means removing the O2 sensors from the exhaust system, so the engine can still operate without them. The function of the O2 sensor is to help keep a balanced air-to-fuel ratio by providing the oxygen levels in the exhaust to the ECU.

If you're in the path of tuning your engine, you are most likely to remove the O2 sensors along with your catalytic converter. This mod is popular for racers as they most likely remove the catalytic converter in their exhaust system, which triggers the check engine light. 

Why Do Owners Bypass O2 Sensors?

Bypassing O2 sensors is efficient in tuning the engine. When your engine runs too lean or rich, you love going off-road yet, and you are not an engine tuner, this option may suit you.

Another reason to bypass O2 sensors is to dismiss several casual errors in your system. When you go off-road, dirt and grime may trigger your O2 sensors often.

And since your car is gearing towards racing and tuning your engine is most important, you would have to delete your catalytic converter, which is a common cause of check engine light.

Now, if your check engine light shows code for faulty O2 sensors, you may have to shell out up to $500 for replacement. 

What Happens If You Bypass O2 Sensors?

• Check engine lights alert

Your ECU will detect the absence of O2 sensors since it is not responding. Replacing it with a dummy sensor will solve this problem.

• Decreased performance

If your system does not work with an O2 sensor, your ECU may not detect problems in fuel injection. If you lack fuel injection, you may have to drive your vehicle with restricted fuel.

• Bad fuel economy

Your computer will not know if the system injects too much or less fuel into the chamber. You may unknowingly drive while wasting fuel. If this is the case, you will not know if unburnt gas ends up in your exhaust system.

• Failed emission test

Without O2 sensors, there will be no way to find if there are leaks in your exhaust system which contain vapors and harmful gases. If there's a leak in your exhaust system, it can damage the catalytic converter. If you have no catalytic converter, you would surely fail emission tests because you have no mechanism to control fumes and harmful gases in your vehicle.

How To Bypass Your O2 Sensor?

You can easily bypass your O2 sensor by replacing it with a dummy sensor. Dummy sensors are fake sensors that do readings like normal O2 sensors. If the dummy sensor is programmed to work with your car, it may be able to send the correct information to your car's computer. 

All you have to do is find the location of your O2 sensors and unplug it. You can usually find them on your catalytic converter. Then plug in the dummy sensor. That's it. 

The secret to making this work is to choose a sensor programmed into your car.

Should you Bypass your O2 Sensor and Delete Your Cat?

These two components of the exhaust system play a vital role in an engine. The absence of any of the two will create long-term problems in the future and affect its efficiency.

First, it will damage your fuel injection system. Your spark plugs could fail. The O2 sensors send a lot of information crucial to the mechanism of your engine. Likewise, the absence of a catalytic converter will disrupt the fuel combustion process as you will need to remove the O2 sensors too.

Now, if you live in places without strict emission standards, you can drive along in the absence of these two.

And if you are an engine builder who knows the way with exhaust systems, then bypassing these two components will not be a problem.

So to answer your question if you should go with it, it depends on how and where you'll use your vehicle. If you always have to bring your car on public roads, do not bypass these components. If you use your car for race tracks or off-road, you can remove the O2 sensors and catalytic converter.