Will a Bad O2 Sensor Cause a Misfire?
In short:
Yes!
A bad O2 sensor can cause a misfire in your engine.
Of course, you might be wondering how will a bad O2 sensor cause a misfire?
Well, the simple answer is that as part of the whole combustion process (the magic that makes your car drive), oxygen mixes with the fuel in your gas tank while the fuel converts to energy.
However, there is an optimal amount of oxygen that should combine with the fuel.
Too much or too little oxygen, and you won’t get the right mix.
Your vehicle will still work with a broken O2 sensor. Vehicles ran for years and years without oxygen sensors.
But, when you don’t have the right oxygen to fuel ratio in your vehicle, not only are you damaging the environment by releasing additional pollutants, you’re damaging your car.
However:
Just because your engine is misfiring, that doesn’t necessarily mean a bad O2 sensor is the cause. There are other things that can cause an engine misfire.
To unmask the culprit, start by figuring out what kind of engine misfire you’ve got.
Is it a “lean” misfire or a constant?
There are two kinds of engine misfires: lean misfires and constant misfires.
Will a bad O2 sensor cause a misfire that’s lean or constant?
Yes. It can cause both. But, what’s the difference?
With a lean misfire, you notice your engine misfires, but only some of the time. And, it seems that you only notice the misfire when the car is idling. As you increase speed, the misfire disappears.
This happens because when you’re idling, the oxygen to fuel ratio is incorrect, causing the misfire. When you accelerate, you change the mix of oxygen to fuel correcting the imbalance.
That’s why the misfire seems to disappear when you accelerate.
In a constant misfire, you notice the misfiring all the time. It doesn’t matter if you’re idling or accelerating or even decelerating. Your engine keeps misfiring.
