Car Maintenance And Repairs

Will A Bad Oxygen Sensor Cause A Car Not To Start?

Mike Cross
Updated Feb 16, 2022
Will A Bad Oxygen Sensor Cause A Car Not To Start

Your car has a lot of different sensors on it. Each one serves its own purpose and helps your vehicle run smoothly.

In this article, the sensor we will look at is the oxygen sensor or O2 sensor.

We will look at what this sensor does and more importantly if it will cause your car not to start if it is not working correctly.

Read on to learn everything you need to know about your oxygen sensor is your car.

Will A Bad Oxygen Sensor Cause A Car Not To Start
Will A Bad Oxygen Sensor Cause A Car Not To Start


What does Oxygen Sensor do?

The first thing we will talk about is what your O2 sensor actually does in your car. The O2 sensor serves a simple, but a very important job in your vehicle. The role of the oxygen sensor is to measure how much oxygen is in the exhaust. This may sound simple, but is a vital part of your car running smoothly. You want the proper amount of oxygen in your exhaust because of pollution controls. Depending on how much oxygen is being sensed in your exhaust the car changes the fuel mixture.

Why is it important to know the oxygen level in the exhaust?

You may be wondering why it is so important to know the level of oxygen that is coming out of your engine thru the exhaust. Well, the reason that it is important is for your car to run correctly, you need the correct amount of oxygen, gas, pressure, and spark in the cylinders of the engine. By having the proper amount of each of these, it creates an explosion that is the appropriate size to move the piston down and rotate the shaft so the power can be transferred to the wheels and the car can move. If the amount of oxygen in the exhaust is more or less than what it is supposed to be, then the car will try to adjust the fuel mixture which is the things listed above, and this will affect how well your car runs.

What happens if the mixture is not right?

So, the next thing you may be wondering is what happens in the engine if the mixture of air, gas, pressure, and spark isn’t right. Well, a few different things can happen. If there is too much oxygen and not enough fuel, then the explosion that occurs may not be strong enough. On the other hand, if there is not enough oxygen and too much fuel, then the blast could be too big leading to damage to the engine. Either way, if the mixture is wrong on any part, then the combustion will not be the proper size and there for the vehicle will not run right.

Can a bad O2 sensor cause a car not to start?

So, getting down to the actual question at hand. If the O2 sensor is not working, will that cause the car not to start? Well, the short answer is no, that will not cause the car not to start. If your vehicle is not starting, then you have a more significant issue than the oxygen sensor is dangerous or dirty. The oxygen sensor helps the car run smoothly, but it does not keep the car from not starting. That is because the oxygen sensor measures the amount of oxygen in the exhaust and it can’t begin to do that till the car is running because there is no exhaust of a vehicle that is off. Even if the sensor is not working and the mixture of oxygen to gas and the other components is wrong, the car will still start.

However, if the mixture is wrong and if it has been wrong for a while from a bad oxygen sensor, then it could have caused more significant damage to the engine that is finally causing the vehicle not to start. For example, if the explosion has been too strong, then the cylinders might be cracked, or the pistons may be damaged. If there is a mechanical damage inside the engine which could come from a bad oxygen sensor, then that might be why the car is not starting, so while a bad O2 sensor can not cause the car not to start on its own, it could lead to damages in the engine that could prevent the vehicle from starting.

What can it cause?

If a bad oxygen sensor can’t keep a car from starting, then what can it cause?

Well, the central issue of a bad oxygen sensor is rough driving and lose of fuel efficiency. This is because if the reading of oxygen that it is getting from the exhaust is not accurate or changing, then the fuel mixture will also continuously be changing.

Also, misfires can happen when your O2 sensor is failing because it is causing an improper mixture of fuel in the engine. The other thing that a bad oxygen sensor can do is harm the environment.

If it is not working right, then your car can be putting too much CO2 and other harmful gases into the air, so not only can a bad oxygen sensor hurt how your car runs, it can also harm everyone and the environment.


So, now you know the answer to if a failing oxygen sensor can keep your car from starting and the answer to that was no a bad O2 sensor can not cause your vehicle from starting. However, you know the other effects of a bad O2 sensor and that it can lead to engine damage and environmental damage. On top of knowing what a bad oxygen sensor can cause you also know what the oxygen sensor actually does in your car. Since you know all these things now you should know that if you think your O2 sensor is going bad that you should clean it or replace it with a new one. That is because you should want your car to run as smooth as possible and be as efficient as possible and a bad oxygen sensor can prevent these things.

Mike Cross
Life is too short to drive with stock audio

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One comment on “Will A Bad Oxygen Sensor Cause A Car Not To Start?”

  1. I have a 2014 f 150 that will crank but not fire 2 ford dealers don't no what's wrong. They put new plugs in and it ran for a day it's pumping to much gas in to the spark plugs and mixing into the oil.they say ford tecs told them to change 02 sensors

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