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How to Delete O2 Sensors from ECM

Sep 06, 2023      View: 6094


The O2 sensor (oxygen sensor) is one of the key components in the emission control system of modern automobiles, and its role and importance cannot be ignored. The O2 sensor mainly monitors the oxygen concentration in the exhaust gas. It detects the amount of oxygen in the combustion process, which helps the engine control module (ECM) know whether the combustion is sufficient. This is critical to ensure maximum combustion efficiency, as complete combustion helps reduce harmful gasses and carbon emissions. Despite the critical role of O2 sensors, some car owners may consider removing them. Let's dig deeper together.



What Are O2 Sensors
Types of Oxygen Sensor
Why Remove the O2 Sensor from ECM
How to Delete O2 Sensors from ECM
How to test the oxygen sensor
Is it OK to drive without o2 sensor
Final Words


What Are O2 Sensors

The oxygen sensor is mainly used to monitor the oxygen content in the exhaust gas after engine combustion, and convert the oxygen content into a voltage signal to the ECU. The ECU analyzes and judges the concentration of the mixture according to this signal, and corrects the fuel injection time to Make the engine get the best concentration of the mixture.

The front oxygen sensor is mainly used to detect the concentration of the mixed gas, and the rear oxygen sensor is mainly used to compare with the signal voltage of the front oxygen sensor to monitor the conversion effect of the three-way catalytic converter. Oxygen sensors generally appear in pairs, with two or four, and are installed before and after the three-way catalytic converter in the exhaust pipe.

The O2 sensor detects the amount of oxygen in the combustion process. Based on the feedback from the O2 sensor, the ECM can adjust the mixture ratio of fuel and air. Real-time feedback from the O2 sensor helps maintain peak engine performance. Inadequate combustion or incorrect fuel mix can result in power loss, rough idle or high temperature issues. In addition, O2 sensors ensure that harmful substances such as carbon monoxide and nitrogen oxides in the exhaust gas are at acceptable levels.


Types of Oxygen Sensor

  • Titanium oxide oxygen sensor

This sensor uses the semiconductor material titanium dioxide (TiO2), whose resistance value depends on the concentration of oxygen in the surrounding environment. When there is more oxygen around, the resistance value of TiO2 increases, and vice versa. Therefore, the resistance value of this sensor changes sharply near the theoretical air-fuel ratio, and causes a sharp change in the output voltage. It should be noted that when the temperature is very low, the resistance of TiO2 will become very high, almost causing the sensor output voltage to approach zero.

  • Zirconia oxygen sensor

The inner and outer surfaces of this sensor are coated with a platinum layer, and the difference in oxygen concentration between the inner and outer sides of the zirconia tube is used to generate a potential difference under certain conditions (high temperature and platinum catalysis). Zirconia sensors are commonly used to measure the concentration of oxygen in the exhaust gas to help control the engine's air-fuel ratio.

  • Broadband oxygen sensor

Broadband oxygen sensor is also called air-fuel ratio sensor, broadband oxygen sensor, linear oxygen sensor, etc. It is a sensor expanded on the basis of a heated zirconia oxygen sensor. Broadband oxygen sensors provide accurate measurements over a wider range of oxygen concentrations, enabling more precise engine control, helping to improve combustion efficiency and reduce emissions.


Why Remove the O2 Sensor from ECM?

Despite the critical role O2 sensors play in vehicle emissions control, some vehicle owners may consider removing them, usually for the following reasons:

  • Performance modification

Some owners wish to make performance modifications to their vehicles, such as increasing horsepower, altering combustion characteristics, or improving acceleration. In these cases, removing the O2 sensor may allow more fuel delivery or alter the fuel mixture ratio for higher performance.

  • Emission standards do not apply

Some owners may be driving older vehicles that may no longer be subject to current emissions standards. In this case, they might consider removing the O2 sensor to reduce maintenance costs.

  • Avoid Troubleshooting

The O2 sensor may be damaged or malfunctioning, causing the check engine light to come on and require repair. Some owners may choose to remove the sensor to avoid these troubleshooting and repair costs.

However, removing the O2 sensor can create a host of problems, including reduced fuel efficiency, increased emissions, reduced engine performance, and violations of environmental regulations. Additionally, some regions may impose strict regulations and fines for removing O2 sensors. Therefore, car owners should consider legal regulations when considering removing an O2 sensor.


How to Delete O2 Sensors from ECM [Step-by-step Guide]


Step 1: Preparation

Before you start removing the O2 sensor, make sure you've done your homework.

Make sure the vehicle engine is not running and the vehicle has been stopped long enough so that components do not overheat.

Wear gloves, a safety mask and safety glasses to ensure your safety and reduce the risk of inhaling harmful fumes.


Step 2: Locate the O2 sensor

Locate the O2 sensor under the chassis of the vehicle. The O2 sensor can be located before or after the catalytic converter, the exact location may vary by model.


Step 3: Disconnect the O2 sensor

Disconnect the wires from the O2 sensor. Typically, this involves squeezing the snap or twisting the connector to release it.

Using the dedicated O2 sensor removal tool, unscrew the sensor by turning it counterclockwise. This may take some force, so make sure the tool is properly attached and handle it carefully to avoid damaging the sensor or other components.


Step 4: Install the dummy O2 sensor

You can now install a dummy O2 sensor, also known as an O2 sensor emulator, to replace the removed O2 sensor. 

Here are the steps to install a dummy O2 sensor:

Turn the dummy O2 sensor counterclockwise into position, as if you were replacing a new O2 sensor.

Connect the wires for the dummy sensors and make sure they are firmly in place.


Step 5: Start the Car

Lower the vehicle to the ground and start the engine. At this stage, you need to check to see if the check engine light is on on the dashboard. If it is not lit, it means you have successfully removed the O2 sensor from the ECM.

It is important to note that removing O2 sensors from the ECM is generally not recommended as it may violate laws and regulations, and may adversely affect vehicle performance, emissions, and reliability. Be sure to understand the regulations before removing an O2 sensor.


How to test the oxygen sensor

If the output voltage of the oxygen sensor changes too slowly (less than 8 times per 10s) or the voltage remains unchanged (whether it remains at a high potential or a low potential), it indicates that the oxygen sensor body or circuit is faulty, and the circuit needs to be checked or the sensor replaced.

There are many ways to detect whether the oxygen sensor is good or bad. Usually, it can be checked with a multimeter, or it can be tested with a special instrument.

  • Multimeter voltage measurement

Before measuring the voltage of the oxygen sensor, please make sure that the oxygen sensor is in working condition, even if it reaches a working temperature above 400°C.

The detection method is as follows: keep the engine speed at around 2500r/min and run it for about 90 seconds, then use a multimeter to measure the voltage at the signal output terminal of the oxygen sensor. Under normal circumstances, the output voltage of the oxygen sensor should be one of the following values: when the engine exhaust gas concentration is high, the oxygen sensor output voltage should be between 0.91V; when the engine exhaust gas is thin, the oxygen sensor output voltage should be between 0.1V ; When the operating temperature of the oxygen sensor is lower than 360°C, the oxygen sensor will be in an open circuit state and there will be no signal output.

  • Oxygen sensor detector detection 

When using an oxygen sensor detector to detect the oxygen sensor, the detection method is similar to the above, except that the multimeter is replaced by the oxygen sensor detector. By observing the blinking and extinguishing of the indicator light on the oxygen sensor detector, you can judge whether the oxygen sensor is in normal working condition.

  • Multimeter resistance measurement

Using a multimeter to measure resistance is to use the resistance characteristics of the oxygen sensor to judge its resistance value in the warm-up state and non-warm-up state, so as to judge whether it is damaged. The resistance value of the normal oxygen sensor is about 300kΩ when the machine is fully warmed up; when it is not in the warmed up state, the resistance value should be infinite.

  • Detection method with car multimeter

Set the function switch of the car multimeter to 4V range, press the DC/AC button to select DC mode, connect the black test line in the COM jack of the multimeter to the metal part of the vehicle, and connect the red test line to the signal line of the oxygen sensor.

Then, keep the car engine at fast idle speed (about 2000r/min), and warm up the engine to ensure that the working temperature of the oxygen sensor reaches above 360°C. When the exhaust gas is thick, the output voltage of the oxygen sensor should be between 0.80.9V; when the exhaust gas is thin, the output voltage should be between 0.10.2V. If the working temperature of the oxygen sensor is lower than 360°C, it will be in an open circuit state and there will be no signal output.

If the measured voltage meets the above requirements, it means that the oxygen sensor is normal; otherwise, it means that the sensor is damaged and needs to be replaced.


Is it OK to drive without o2 sensor

Yes, the engine can technically work without oxygen sensors (O2 sensors). However, it's essential to understand that O2 sensors play a critical role in the engine's performance and emissions control. 

Oxygen sensors are responsible for monitoring the oxygen levels in the exhaust gases and providing feedback to the engine control module (ECM) or engine control unit (ECU). Based on this feedback, the ECM adjusts the air-fuel mixture to maintain optimal combustion efficiency. Without functioning O2 sensors, the ECM won't have real-time data on the air-fuel ratio.


Final Words

Deleting O2 sensors from the ECM is technically possible, but it's important to emphasize that it's not recommended practice. Rather than removing these sensors, it is advisable to periodically clean or replace them as necessary. O2 sensors play a crucial role in your vehicle's emission control system, and tampering with them can lead to various issues.

Before considering any significant alterations to your car, it's highly recommended to consult with a trusted mechanic. They can provide expert guidance on how to maintain your vehicle's performance while staying within legal and environmental compliance.



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  • Do O2 sensor spacers really work
  • In certain cases, O2 sensor spacers can be effective. When you install a spacer of the appropriate size, it can reposition the sensor so that it's no longer directly exposed to exhaust gases. As a result, the concentration of oxygen around the sensor decreases, creating the appearance of a richer fuel mixture. This can lead to a higher sensor voltage reading sent to the Engine Control Unit (ECU).
  • Will removing catalytic converter affect o2 sensor
  • Yes, removing the catalytic converter can have a significant impact on the O2 sensor. The O2 sensor, specifically the downstream sensor, plays a crucial role in monitoring the performance of the catalytic converter. It measures the oxygen content in the exhaust gases downstream from the converter. If the catalytic converter is removed, the O2 sensor will not receive accurate readings because there will be no catalytic converter to perform its emissions-reducing function. In summary, removing the catalytic converter can affect the O2 sensor and result in various negative consequences, including increased emissions, poor engine performance, and potential legal issues. It is generally not recommended to remove the catalytic converter unless it is replaced with a suitable alternative that complies with emissions regulations in your area.
  • How necessary is an o2 sensor
  • In simple terms, O2 sensors play a crucial role in regulating the air-fuel ratio of your car's engine. Every combustion event in your car's engine relies on the ignition of a precise mixture of air and fuel. When this ratio is maintained at an optimal level, your car will run smoothly and idle without issues.
  • What happens if I unplug downstream o2 sensor
  • The downstream sensors are responsible for monitoring the performance and condition of the catalytic converter. Disconnecting them will eliminate this functionality and trigger a CEL (check engine light) or MIL (malfunction indicator light) in the vehicle.
  • Is there a way to bypass O2 sensors
  • There exist various methods to bypass the oxygen sensor, including the use of an O2 sensor extender or adapter, or even substituting the original oxygen sensor with a counterfeit one. However, it's important to note that you cannot repair a malfunctioning O2 sensor; the only solution is to replace it, as these sensors do not have serviceable components.
  • What happens if you delete O2 sensors
  • The complete engine management system in your vehicle relies on the information provided by the oxygen sensors. Consequently, eliminating them will render the engine unable to operate optimally as intended. It's important to note that if O2 sensors are causing issues, they should be diagnosed and replaced rather than removed.