How To Bypass Oxygen Sensor: 3 Guaranteed Methods – Bypass O2 Sensor Simulator

How To Bypass Oxygen Sensor

Fool Your Car Computer With These Simple Tricks! And Save Money

If you’re into off-road racing or are not very good at tuning engines, bypassing the oxygen sensor might be your best choice. Not only that, but it also helps engines in reversing common system failures.

When your car’s catalytic converter expires or the oxygen sensor does not work properly, you may be tempted to just replace the entire unit. However, this is not always the best option. There are alternatives that can save you money without having to replace the entire catalytic converter.

The car may show an engine light if the catalytic converter has expired or if the oxygen sensor doesn’t work properly. There are different methods for bypassing the O2 sensor, which includes the replacement of the original oxygen sensor with a dummy O2 sensor or using an O2 sensor extender/adaptor.

In actuality, you cannot repair a malfunctioning O2 sensor. The only way you can solve the issue is to replace it. This sensor is made of parts and technology that cannot be fixed. This sensor has a rather simple diagnosis and is quite inexpensive to replace. 

This powerful article teaches you 3 different methods to bypass oxygen sensors. It will help you save money and time. It is a must-read for all car enthusiasts.

How To Bypass Oxygen Sensor

Oxygen Sensor Located After Catalytic Converter
Rear Oxygen Sensor Located After the Catalytic Converter

When an engine is running, it produces gases that are harmful to the environment. A catalytic converter helps reduce these harmful emissions by converting the pollutants into less harmful substances.

If your car doesn’t have a cat converter, you can “bypass the oxygen sensor” in order to ensure that the car will still run properly. Bypassing the sensor means that your car will not be able to monitor and adjust the air/fuel mixture, so it’s important to make sure that your car is properly tuned before doing so. Additionally, it’s important to keep in mind that bypassing the sensor will result in increased exhaust gases and decreased fuel economy.

Bypassing the sensor will tell the car’s computer to ignore the amount of oxygen in the exhaust and allow the car to run rich (more fuel than air). This will not damage your engine, but it will produce more exhaust gases.

If you enjoy off-road racing or have limited engine tuning experience. Bypassing improves engines in reversing unexpected system failures. In the absence of a cat converter, an O2 sensor bypass is also necessary. Your check engine light will always come on without it. Bypassing the O2 sensor is not suggested if you’re trying to pass an emissions test or keep the check engine light off.

With the O2 sensor bypassed, it’s possible to disable the engine Check Engine Light even if exhaust gases are poor or allow the engine to be tuned more flexibly. Below are the three different methods through which you can bypass the sensor.

One last suggestion: If you are unsure whether or not to bypass your car’s O2 sensor, we recommend consulting with a professional mechanic or automobile expert. They will be able to provide helpful advice and guidance for your particular situation.

Method 1. How To Bypass O2 Sensor Using Oxygen Sensor Simulator OR RC Circuit (Also Known As Dummy Oxygen Sensor)

How To Bypass Oxygen Sensor Using RC Circuit
How To Bypass Oxygen Sensor Using RC Circuit

In this method, the procedure for bypassing the rear oxygen sensor signal circuit is explained in steps with a detailed description. First of all, make sure that your vehicle has a problem with the O2 sensor and is showing the P0420 Diagnostic Trouble Code when checked by the OBD – II. There are some symptoms of it as well, which include poor performance, illuminated check engine light, reduction in power after the vehicle warms up, and a rotten egg smell coming from the exhaust pipe.

Catalytic converters are designed to convert the harmful pollutants emitted from cars into less harmful gases. However, if the converter’s efficiency falls below a certain threshold, it can no longer effectively do so and shows P0420 Diagnostic Trouble Code when checked by the OBD – II, and may require replacement.

In this article, we’ll explore how to bypass an oxygen sensor when a catalytic converter’s efficiency falls below this threshold and what you can do to prevent it from happening.

When the code is detected, collect the live data of the downstream oxygen sensor in voltages by using the scanner for the engine running at 2500 RPM. The values of the voltages should be constant from 0.4 to 0.6 voltages.

If it is fluctuating with a lot of variations from a very low value to an extreme value from 0.2 to 0.7 volts, then it will confirm that the O2 sensor is faulty. Placing an O2 simulator or RC circuit (which means a capacitor and resistor in the O2 sensor’s signal circuit) makes these extreme fluctuating values constant and tricks the car computer into believing that the O2 sensor is working fine.

An O2 simulator also known as a dummy oxygen sensor used to bypass the sensor is a device that can be used to trick a car’s computer into thinking that the car’s exhaust system is functioning normally, even if it is not. An O2 simulator is a very small-circuit board plug-in embedded into a housing to provide a waterproof, exceptionally small simulator that’s exceptionally compact. The O2 simulator provides the PCM with a signal simulating a healthy catalytic converter.

If you do not have an O2 simulator circuit board. Don’t worry, you can use an RC circuit that functions the same as the O2 simulator. The RC circuit consists of a capacitor and resistor that functions as a filter that will gradually charge and discharge to give us a curve that the car computer will accept without throwing away the engine code.

Remember bypassing can be done with rear or downstream sensors, not with oxygen sensors before the catalytic converter.

Following are the steps that should be followed for bypassing an oxygen sensor using an RC circuit.

  • First of all, take out the rear oxygen sensor with the oxygen sensor removal tool and disconnect the wires which are of a different color. One wire will be positive and the other one will be negative (earth). Here, we are targeting the signal circuit not the heater circuit.
  • The positive and negative wires can be checked by using the multimeter. The signal circuit will be used for the bypass.
  • Now, place a resistor parallel to the signal circuit. Take a capacitor that must have the values of the capacitance of 1.5 microfarads and at least 5 volts. The capacitor has a side positive and the other one negative.
  • Connect the positive side of the capacitor with the positive wire (signal wire) of the signal circuit of the O2 sensor and similarly, connect the negative wire with the negative (earth) wire of the signal circuit.
  • Now, after connecting the capacitor, place a resistor in series with the signal circuit. The resistor must have a resistance value of 1 mega ohm. Connect the resistor between the capacitor-connected wire and the O2 sensor. The positive wire going from the O2 sensor will be connected to the resistor and then there will be the capacitor.
  • Tape the resistor and all the other circuits to avoid any injury and the short circuit.
  • Now, the oxygen sensor is bypassed. Start the engine and let the engine run.
  • Check the value of the voltages of the oxygen sensor for confirming whether it is correctly bypassed or not. This capacitor and resistor create a constant amplitude in the graph and your car computer thinks the oxygen sensor is OK.

Now, drive the car for at least 30 km without turning the engine off. If you turned off the ignition switch without completing the mentioned distance, the engine check light will blink five-time after turning ON the ignition switch. And again you have to drive for 30 km, doing so, the ECM will then set the new value and the car is ready to drive.

Because it runs in cycles, this is the most difficult component. So, if the check engine light stays on, keep driving in a relaxed manner until it turns off. Once the cycle is complete, your car’s computer will continue to work as if the oxygen sensor is still present and properly tuned. When this is completed, it indicates that the bypassing has been successful.

Method 2. How To Bypass an O2 Sensor Heater Circuit Using Resistor (Fix Check Engine Light)

How To Bypass Oxygen Sensor Heater Circuit
How To Bypass Oxygen Sensor Heater Circuit

If you get the engine code for the heated oxygen sensor malfunctioning, and you want to bypass the oxygen sensor heater circuit. In this method, you need to bypass the sensor by attaching the resistor of specific resistance with the heater circuit of the oxygen sensor, which is explained below.

The oxygen sensor’s heater circuit is used to heat the element of the oxygen sensor in order to produce a voltage signal that reflects the oxygen levels in the exhaust. When this circuit does not work, the oxygen sensor will not be able to heat the sensor up to its proper operating temperature and will not produce a voltage signal, which can cause the engine to run poorly and can cause to show the check engine light.

Adding a resistor to the heater circuit of the oxygen circuit leads the car computer into believing that the oxygen sensor is functioning properly. You may avoid having the check engine light on all the time by bypassing the sensor.

Following are the steps that should be followed for bypassing an oxygen sensor’s heater circuit in your vehicle.

  • First of all, the vehicle must be cooled down, if the engine was operating. As this work is related to the engine as well as the exhaust, for that reason, the vehicle has to be at the normal temperature for the safety of the operator.
  • Now, take out the oxygen sensor with o2 removal, and check the wires of the oxygen sensor. There will be two wires of the heater circuit connecting with it.
  • Now, Place the resistor between the two wires of the heater circuit according to the oxygen sensor resistance value. You can check the oxygen sensor resistance by checking the heater circuit with a multimeter. Most oxygen sensors’ heater circuits have around 5, 6, or 7 ohms resistance.
  • Now, solder the resistor to heater’s positive and negative wire and then cover it with tape to avoid injuries and for safety as well. You can connect the resistor in any direction.
  • After that, drive the car at a slower speed so that the electronic control module will get the data from the oxygen sensor and will hide the check engine light.

When the sensor is functioning properly, the resister will provide signals to the computer. Most people can figure it out because it is really straightforward.

Related Post: How To Bypass O2 Sensor Heater Circuit: (Resistor Bypass)

Method 3. How To Bypass Oxygen Sensor Using Oxygen Sensor Extender/Adaptor (Not Recommended For Emission Test)

Oxygen Sensor Extender
Oxygen Sensor Extender

Another method to bypass the oxygen sensor is by using the oxygen sensor extender. The procedure for installation is simple.

If your car’s catalytic converter does not work properly, the rear oxygen sensor or the second sensor detects fault by sensing more oxygen level, so an oxygen sensor extender/adaptor is used to sense less oxygen in the exhaust gas and trick the car computer into believing that the catalytic converter is working perfectly.

An oxygen sensor extender is a device that is inserted between the oxygen sensor and exhaust pipe in order to extend the life of the oxygen sensor so that your O2 sensor detects less oxygen in the exhaust pipe. The extender helps to keep the sensor cooler and reduces the amount of exhaust gas that comes in contact with the sensor.

Following are the steps that should be followed for bypassing an oxygen sensor using an oxygen sensor extender/adaptor in your vehicle.

  • First, the vehicle must be cooled down, if the engine was running. It is related to the engine and exhaust which is why the car must be at a normal temperature to work for the sake of safety.
  • Now, when the vehicle is cooled down, take the oxygen sensor extender and remove the oxygen sensor with the O2 sensor removal tool.
  • After removing the oxygen sensor, attach the oxygen sensor extender between the sensor and the exhaust pipe.
  • The oxygen will now pass through the sensor without any hindrance and it will not be sensed much.
  • After installing the extender, drive the car at a low speed at the start so that the ECU will set the value and will send the data to the engine for the injection of the fuel accordingly.

The oxygen sensor extender may be illegal to install in some countries so before installing it, be careful about the rules and regulations and repair or replace the oxygen sensor as soon as possible by visiting the mechanic or auto workshop. This method is not recommended for emission tests due to its lack of efficacy in capturing the full scope of pollutants emitted over the life cycle of a process.


Can you bypass the oxygen sensor on a vehicle?

The answer is yes, but it’s not always the best option. In some cases, it could be illegal to bypass the O2 sensor on a vehicle. However, it is possible to do so in some cases. Other times, it may not be necessary or advisable to bypass the sensor.

Is there a fuse for oxygen sensor?

Yes, there is typically a fuse for the oxygen sensor heater circuit, but the position of the oxygen sensor fuse may vary from model to make.
Related O2 Sensor Heater Fuse Location – Here’s How To Find It!

What happens if I drill holes in my catalytic converter?

Oxygen sensors are part of the emission control system. It measures the amount of oxygen content to increase engine performance. It adjusts air-fuel mixture accordingly. If you drill holes in your catalytic converter, the exhaust gases will escape through the holes instead of being forced through the catalyst. This will reduce the converter’s ability to clean up the exhaust gases, which may eventually reduce its effectiveness and causes your car to fail the emission test. In some states, it is illegal to drive a vehicle with a damaged or modified catalytic converter, so you could be fined if you’re caught.

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    2 thoughts on “How To Bypass Oxygen Sensor: 3 Guaranteed Methods – Bypass O2 Sensor Simulator”

    1. Hi engineer saab. I m dr RAUF from Peshawar. I have a corona car with 3sfe 2000 cc engine on it which is quite a fuel guzzler. It barely gives me 6 to 8 km per liter of petrol. I also installed the O2 sensor on it but still the car is running rich on fuel. Is there anyway I can cheat my car ecu to consume less fuel? Thanks in anticipation.

      1. Dear Dr. Rauf,

        Welcome to my blog! Fuel consumption is a major problem for many drivers, but there are some clever techniques to improve your gas mileage. I’m excited to share some of the techniques I’ve discovered that can help reduce your fuel consumption and help you save money on gas. I look forward to sharing my tips with you and helping you get the most out of your vehicle. Below is one of my best articles about saving gas while driving.

        How To Save Gas While Driving: 23 Hacks! The Ultimate Guide

        Thanks for visiting!

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