Will a Bad O2 Sensor Cause a Random Misfire?

Automotive engines have a framework that is mechanically supported. All the systems work in synchronization with each other and any hitch to a unit might damage the system. My car broke down a couple of days ago, a great mile away from my destination. It was pretty bad, I had signs, but I thought they were normal. If you have found a sign suggesting that your engine is misfiring, then I've got something for you. Some car owners often ask; “Will a bad O2 sensor cause a random misfire?” My answer is yes!

After reading this article, I bet you'd agree.

The O2 Sensor

The O2 or oxygen sensor is a quite important device designed to sustain the whole engine system. In the human brain, hypoxia (shortage of oxygen) is detected by chemoreceptors in the medulla oblongata. This triggers a rapid response from the respiratory tract. The lungs pump out more Co2 and draw in more o2.

The O2 sensor is somewhat similar to the chemoreceptor of the medulla oblongata. It is somewhat tiny in size and is situated at the extreme end of the burnout (exhaust) system. It plays a key role in the overall combustive ability of the combustion engine.

Will a Bad O2 Sensor Cause a Random Misfire

Combustion engine performance

Combustion engines operate based on principles of thermodynamics. Fuel is an ingredient of fire, and fire generates heat. An essential feature of combustion is the presence of oxygen. Without oxygen, fuel fails to burn. When fuel fails to burn, heat is not generated and maybe the pressure to drive the pistons drops or rather, the compression/spark ignition fails to drive the engine. Most fuels are light oxygenated oils or highly combustive hydrocarbons. The exhaust-oxygen ratio has to be fair to maintain a good engine.

How the oxygen sensor works

I feel we should have a basic discussion on the oxygen sensor. The duty of an oxygen sensor is to measure the oxygen level in the exhaust chamber of the engine. This information regarding oxygen measurement and exhaust analysis comes in to aid in a few cases.

Most importantly, this information is passed to the Power-train Control Module (PCM). The PCM determines the air-fuel ratio of the engine in the combustion chamber.

Secondly, this information is used to let the fuel injection system and the engine timer to work efficiently. Wrong data passed down to other operating controls would let these two components work defectively. The result is the bad driving experience that most drivers go through. In the most horrible cases, it leads to engine misfire. The oxygen sensor keeps playing a crucial role in environmental emission. The location of the oxygen sensor is right at the exhaust system of the engine.

How a bad O2 sensor causes a random misfire 

A bad oxygen sensor has a massive impact on engine malfunctioning such as misfires. As the data-driven from the sensor determines many other parameters of the combustion system, it’s a serious problem that needs expert care. Wrong data from the sensor may have a negative impact on the emission from the exhaust system.

It is good that you know the possible reasons for engine misfire through a bad oxygen sensor. There are parameters to be considered in handling this issue.

The intervals of combustion, the control engine timing, the air-fuel ratio are combustion parameters. These direct parameters are related to the data read from the oxygen sensor. If these parameters lead to functions going wrong, improper and constant or occasional misfire of the engine may occur. Apart from the misfire, there are many other impacts that can happen. Diagnosis by an experienced automobile technician will expose them.

Symptoms of engine misfire:

Often, engine misfire is related to performance problems. Some common examples are - exhaust smoke puffing, loss of drive power, stalling, and jerking.

You can tell whether the oxygen sensor is bad or good only by igniting the engine.

You will also have a complete understanding of your O2 sensor by running diagnostic checks with an OBD2 Scanner.

Run any of these three checks:

  • Observe the Check Engine Light:

Is it coming on or not? The first task for the  whole inspection is to check the engine light. It tells you whether the sensor is working fine or not. This light will turn on or blink if the car oxygen sensor is malfunctioning. There are other causes of the ‘check engine light' turning on so, when you notice the light blinking, take your car to an expert to decipher the problem.

  • Check for foul egg exhaust smell and sooty smoke:

A basic but effective way of identifying a bad O2 sensor is through the exhaust smell. Since the air to fuel ratio is periodically or constantly disrupted, a bad smell, with or without sooty smoke is a good indication. In most cases, the smoke is usually puffy black.

  • Poor Gas Mileage:

Another way to identify a poor oxygen sensor is from a poor gas mileage. Cars are built with read-outs on gas consumption per mile. There should be a definite mileage for the gas fuel that it intakes. But with a poor O2 sensor in place, you will see a significant drop in the mileage of the gas. Too much fuel is injected by fuel injector inside the engine due to the misreading of oxygen level. Thus reduction in gas mileage takes place.

Replacing a bad O2 Sensor

As I did replace mine soon enough, you should do yours as well. After seeing signs of a bad sensor, you should make an attempt to replace it. This avoids possible damage done to the combustion mechanism.

Here are some helpful tips:

1. Inspect gas mileage after every 50000 to 80000 miles of driving. This periodically checks out the oxygen sensor and its health. If you face issues at some periods, consider replacement with a new oxygen sensor.

2. If your car is 15 years old or more, you should consider changing the oxygen sensor.

3.Take your car to professionals from time to time for full diagnosis since they run on complicated and complex mechanisms. There are multiple processes going on at any engine firing moment, so, a malfunction may lead to several defects, and the whole driving experience can become unexciting as a result.

Will a bad O2 sensor cause a random misfire? Do you know any better now? I believe you do and I’m glad to be of help.

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