Can a Bad O2 Sensor Cause a Misfire

As a car owner and a driver, you will experience a misfire once in a while in your car as part of your driving experience. The misfire can be caused by so many things such as loose or bad spark plugs, bad fuel injectors, problems with the fuel lines, etc., but can a bad o2 sensor cause a misfire?

Yes, a bad o2 sensor can cause a misfire. The O2 sensor is responsible for monitoring the level of oxygen in the exhaust gases to adjust the air-fuel mixture for excellent combustion. If the O2 sensor goes bad and provides inaccurate data, it can lead to an improper air-fuel mixture, which in turn can result in misfires.

Can a Bad O2 Sensor Cause a Misfire?

A bad o2 sensor can indeed cause a misfire if it fails to adjust the air-fuel mixture for flawless combustion.

When the oxygen sensor goes bad, it can send incorrect data to the ECU, causing the engine to receive inaccurate information about the air-fuel mixture which can result in the ECU adjusting the mixture incorrectly, leading to a lean or rich condition.

If the bad O2 sensor continues to report a constant lean condition which means too much oxygen in the exhaust gases, the ECU may try to compensate for this by increasing fuel delivery, leading to a rich air-fuel mixture, which causes misfires due to incomplete combustion.

However, a bad 02 sensor can cause a misfire if the sensor indicates a consistently rich condition which means too little oxygen in the exhaust gases, the ECU may reduce fuel delivery, leading to a lean air-fuel mixture.

How to Tell If an O2 Sensor is Causing a Misfire

To tell if the o2 sensor is the cause of your engine misfire, you should:

1. Scan the Car and Check for Error Codes

The first step to knowing if the o2 sensor is the cause of your engine misfire is by scanning the car with an OBD II scanner for error codes. The scanner should be able to read and tell you whether the o2 sensor is bad and causing your misfire or not. With the information from the scanner, you should know whether to replace the sensor or have it cleaned.

2. Inspect the O2 Sensor

You can also inspect the o2 sensor for any issues such as wiring and connections for damage, corrosion, or loose connections. If the sensor is not properly connected or the wire has been cut, it will affect its performance hence causing a misfire, therefore, examine the sensor and be sure it is rightly tightened in its location.

3. Test the O2 Sensor

Another method through which you can diagnose if your o2 sensor is the cause of your misfire is by testing the sensor to ensure it’s still in good condition.

You need to test the O2 sensor’s voltage output using a multimeter or scan tool to determine if it is providing accurate data or not. If the sensor is not functioning within the specified range, it may need replacement.

If after diagnosing it becomes obvious that the o2 sensor is the cause of the misfire, you should have it replaced immediately. There is a difference between having a working o2 sensor and a catalytic converter below the threshold. While you can use a 02 sensor spacer to temporarily fix the issue, you must replace the o2 sensor once it goes bad.

Can a Bad O2 Sensor Cause Multiple Misfires?

Yes, a bad o2 sensor can cause multiple misfires (P0300 code) if the air-fuel mixture is too rich (too much fuel) or too lean (too little fuel). A rich mixture can result in incomplete combustion, while a lean mixture can cause misfires due to inadequate fuel for combustion.

As reiterated earlier, an O2 sensor that works well helps the engine maintain the right air-fuel ratio by providing data about the oxygen content in the exhaust gases. However, if the O2 sensor detects too much oxygen in the exhaust, it indicates a lean mixture and the ECU will increase the fuel supply, causing a misfire. The same goes for when there’s too little oxygen in the exhaust which means a rich mixture.

Can Replacing an O2 Sensor Fix a Misfire?

Yes, replacing a bad o2 sensor can fix a misfire if the misfire was caused by an incorrect air-fuel ratio from the bad sensor. Once the sensor is replaced, the engine will go back to its normal operating condition with the misfire gone.

Can a Bad O2 Sensor Cause Misfire on Cylinder 2?

It is possible for a bad o2 sensor to cause a misfire in cylinder 2 but it’s rare. While a bad oxygen sensor can cause a random/multiple engine misfire, it is likely not to cause a misfire in cylinder 2 except in extreme conditions.

Moreover, the oxygen sensor can only cause a misfire when its functionality is tampered with, meaning that it will leave an o2 sensor error code for you to know exactly what is wrong and that code is not a misfire in cylinder 2.

Therefore, if you’re having a misfire in cylinder 2, check your spark plug, ignition coil, or fuel injector for cylinder 2. You may find your problem.


Having a faulty o2 sensor can be frustrating because it can cause a misfire which in turn can affect the power output of the engine. If you notice that the o2 sensor is the cause of your engine’s misfire, please have it replaced immediately to solve the problem because it is not safe to drive with a bad o2 sensor. It can cause too much harmful emissions, poor gas mileage, etc.