Will Bad O2 Sensor Cause Misfire?

faulty old oxygen sensor

The oxygen sensor plays quite an important role in the whole engine system. Although it’s pretty tiny in size and is located at the external(exhaust) system. But it has some important role to play on the overall performance of the engine.

Now the question under our concern at this moment is: Will a bad O2 sensor cause misfire? Well, we will say that- it’s YES!

The bad oxygen sensor has a massive impact on engine malfunctioning like misfires. As the data driven from the sensor determines many other parameters of the combustion system, it’s a serious problem to take care of.

In this article, we will be discussing some basics about the oxygen sensor, the possible reasons for an engine misfire through a bad oxygen sensor, the symptoms of understanding a bad sensor, and some quick steps to take in that situation.

Take a few minutes to break from whatever you are doing, and let’s jump in-

The Basics of Oxygen Sensor

Before diving deep into the article, let’s have some basic discussion on the oxygen sensor, as it is going to be the backbone of the topic we are talking about.

The duty of an oxygen sensor is to measure the oxygen level in the exhaust panel of the engine. This information regarding oxygen measurement comes in help in a number of cases.

  • First of all, this information is passed to the Power Control Module(PCM), and the PCM determines the air-fuel ratio of the engine.
  • Secondly, this information is used to let the fuel injection system and the engine timer work efficiently. Bad or incorrect data would let these two components work with wrong data, resulting in a bad driving experience. In the worst cases, it may lead to misfire as well.
  • Thirdly, the oxygen sensor keeps playing an important role in environmental emission. Wrong data from the sensor may have a pretty negative impact on the emission from the exhaust system.

The location of the oxygen sensor is right at the exhaust system of the engine.

Read: How to make your exhaust loud

will bad o2 sensor cause misfire

Can a Bad O2 Sensor Cause Misfire?

So, this is the core of today’s article where we will be discussing the possibility of a misfire in the engine due to a bad oxygen sensor. If you are looking for a straightforward answer, then YES, an oxygen sensor might cause the engine to misfire.

The reason is, that the oxygen sensor has many things to do with the function of the engine.

For some examples, control engine time, the intervals of combustion, and the air-fuel ratio- are the direct factors that are related to the data read from the oxygen sensor.

If those functions go bad or improper, they may lead to a constant or occasional misfire of the engine.

Apart from the misfire, there are many other impacts that can happen. Mostly, those problems are related to performance problems. Some regular examples are- the loss of power, stalling, hesitation, etc.

The Symptoms: What to watch out for?

First thing first, you can’t tell whether the oxygen sensor is bad or good just by putting your hands on the steering wheel. To end up with a complete understanding of whether your O2 sensor is malfunctioning, you should try out one of these three check-ups-

Check Whether the Check Engine Light is Coming On or Not

The first line of the whole defense is the check engine light, and it can tell you whether the sensor is working fine or not. This light will turn on or blink if the car oxygen sensor is working badly.

Also, the reason behind checking the engine light turned on can be some more. So, when you notice such blinking, it’s better to take it under the vision of an expert and figure it out.

Rotten Egg Smell and Black Smoke

A funny, but yet effective way to identify a bad O2 sensor is through smell. As the air to fuel mixture is being disrupted, a bad smell will come out.

Also, it will create an excessive level of black smoke. With the regular exhaust system, black smoke comes out quite often. But in this case, the ratio of black smoke will be quite high.

Bad Gas Mileage

The third way to identify a bad oxygen sensor is the bad gas mileage. Usually, your car should have a definite mileage for the gas fuel that it intakes.

But with a bad sensor inside, you will see a significant drop in the mileage of the gas. As too much fuel is injected inside the engine due to the misreading of oxygen level, this deduction in gas mileage takes place.

Tips for Replacing the O2 Sensor

Now, as soon as you have detected a bad sensor, you should make an attempt to replace it. Here are some quick tips in this regard –

  1. After every 60000 to 90000 miles of driving, check out the oxygen sensor and its health. If you face issues, replace it with a new oxygen sensor.
  2. If your car is at least 15 years old, you should be more careful about frequently checking the engine oxygen sensor health.
  3. Take help from professionals in case you need to.

As you know, a car is a complicated and complex mechanism. And there are thousands of processes going on at any given moment. So, one malfunction may lead to several others, and the whole driving experience can turn bad due to that.

If the problem is misfiring, a bad O2 sensor can be the culprit. But before shooting into the dark, you should take proper checkout attempts either by yourself or a professional. And if needed,

keep an extra oxygen sensor in the car, in case of emergency!


The car will misfire and drive poorly. This is because when the oxygen sensor detects too much or not enough air in your engine, it sends out an incorrect signal to the ECM that tells it how much fuel should be injected into your cylinders.

If you suspect this may be affecting your vehicle’s performance, take it to see a mechanic soon for testing before there are any more severe problems!