Select address
Select Your Vehicle
Go back to Blog

What Are the Symptoms of a Bad Oxygen Sensor?

Published by: Edison
Date of Publish:

Do you wonder at times whether the oxygen level of your car surpasses the capacity of oxygen or can reduce it? So, it is very straightforward; you can verify the sufficient quantity of oxygen that your automobile needs for the combustion that occurs internally using an oxygen sensor. Your O2 sensor's failure to detect oxygen at that level will get you into serious difficulty, though.

A malfunctioning oxygen sensor located in your car might create various difficulties. It is potent enough to cause the too lean or too rich condition of your car’s engine. Reduced fuel efficiency and higher emissions are two possible outcomes. Your engine may run rough or misfire as a result. As a result, early detection of a malfunctioning oxygen sensor is critical.

In this blog post, we'll discuss various typical signs of a faulty oxygen sensor. Continue reading to find out the all those symptoms!

What Does a Bad Oxygen Sensor Mean?

There are several instances where you may claim that your automobile has a defective O2 sensor or is soon to fail. One option is to look at the code written in the sensor. Having a P0430 code indicates a problem with the catalytic converter and an O2 sensor that has failed.

Another method to discover whether the Oxygen sensor has failed is by glancing at the check engine light. If the check engine light is on, this signifies a problem with the automobile and that the Oxygen sensor may have failed. The vehicle's performance may also be examined at this point. There is a possibility that the Oxygen sensor (02) has failed if the vehicle is not functioning correctly or is releasing excessive exhaust fumes.

As soon as you notice a problem with your oxygen sensor, get it replaced. Unless you do, it might be damaging to your vehicle. A defective O2 sensor might cause the engine to run rich, which means it’s generating too much gasoline and not enough air. This may lead to various issues, including lower fuel efficiency, deterioration of the catalytic converter, and sometimes engine failure.

What Are the Signs of a Faulty Oxygen Sensor?

When the O2 sensor is faulty, it has the potential to create wide types of issues. If any of the symptoms listed are present in your vehicle, it is possible that the oxygen sensor is malfunctioning and needs to be replaced:

1. A Rough Idling

It is a good idea to get the oxygen sensor examined if you are having rough idling in your vehicle. It's possible that here is where the issue begins. When you attempt to accelerate, the engine has a jerky idle and hesitates when it should be moving faster. If you have such problems, you should get the oxygen sensor tested out as soon as possible.

2. The Emission Tests Were Not Passed

It is an essential part to get the emission tests done for the comprehensive inspection procedure on cars. They contribute to ensuring that your cars are being operated in the boundaries of legal actions and comply with all of the standards about safety. If a vehicle does not pass the emissions test, this may indicate that there is a problem with the oxygen sensor in your vehicle.

3. Fuel Mileage is Decreasing

If you have noticed a decrease in the gas mileage achieved by your vehicle, there is a significant probability that the issue lies in the O2 sensor. The oxygen sensor in your vehicle contributes to the control the ratio of fuel and air in your vehicle’s engine. However, when it's terrible, it's conceivable that your vehicle won't achieve the high fuel economy possible, which will decrease the amount of gas mileage it gets.

4. Insufficient Engine Power

It is not unheard of for a vehicle's engine to demonstrate poor proficiency or may fail entirely. This is caused by a faulty oxygen sensor in the majority of instances. If your vehicle's engine performance is subpar, you should examine the oxygen sensor to determine whether or not it requires to be changed.

5. Noises from the Engine

A faulty O2 sensor may cause sounds coming from the engine. The following are the three primary forms of engine sounds that a defective O2 sensor may cause:

  • Knowing Noise: This noise is produced by an engine with an air/fuel mixture that is too lean and has to be adjusted. A faulty oxygen sensor will cause the engine to run excessively lean, resulting in a banging noise produced by the vehicle.
  • Pinging Noise: This noise is produced by an engine with a vibrant combination of air and gasoline. Pinging noises will arise if the O2 sensor in the engine is faulty since this will cause the engine to run overly rich.
  • Rattling Noise: Typically, a faulty connection for the O2 sensor is the source of this sort of noise. A rattling sound will be produced if the connection is not secured with enough force.

6. Black Smoke from the Tailpipe Exhaust

A malfunctioning oxygen sensor might result in the production of black exhaust gases. This is because a faulty oxygen sensor might result in the engine running rich, indicating an excessive amount of gasoline inside the engine.

When this happens, the exhaust will have a dark color due to the surplus gasoline. One such possibility is an issue with the air intake system, which results in the sensor not receiving an adequate supply of oxygen. Because of this, the engine may develop a rich running condition and create dark exhaust gases.

7. The Exhaust Smells Like Rotten Eggs

A malfunctioning oxygen sensor is usually to blame when a vehicle's exhaust gives off the odor of rotten eggs. Because of the faulty oxygen sensor, the fuel burns inefficiently, so not all of the fuel is transformed into usable energy.

As a result, a significant percentage of it is converted into toxic fumes, which are then released from the engine and mixed with the air. These vapors include sulphur dioxide, which is the primary substance that is responsible for the rotten egg odor that is produced.

There are a few other potential explanations for why a vehicle may emit this odor, but a malfunctioning oxygen sensor is the most typical cause. Around seventy-five percent of automobiles exhibiting this odor are believed to have a malfunctioning oxygen sensor.

8. Engine Running Too Hot

A faulty oxygen sensor may also cause the engine to overheat, which is another one of its symptoms. The fact that the sensor cannot accurately interpret the air-to-fuel ratio is the primary reason why this occurs. This may result in the engine running too richly or too leanly, which would cause it to overheat. Because of the faulty sensor, the vehicle's engine can potentially die in rare instances.

9. The Catalytic Converter Broke Suddenly

A sudden failure of the catalytic converter is a typical indication that the O2 sensor needs to be replaced. The O2 sensor keeps an eye on the ratio of air to fuel in the combustion chamber and reports its findings to the engine management unit. When it breaks down, the air-to-fuel balance in the engine falls out of whack, which may lead to the catalytic converter overheating and eventually failing.

10. Illuminating Check Engine Light

One of the most typical signs that an oxygen sensor needs to be replaced is when the check engine light begins to blink. This happens when the sensor cannot accurately read the quantity of oxygen in the exhaust system. Consequently, the engine will be unable to regulate the air-fuel mixture appropriately with time, which may cause the engine to get damaged.

Is It Dangerous to Drive a Car If the Oxygen Sensor Isn't Working Properly?

It defies logic to keep driving your vehicle despite being aware you have indications of a faulty O2 sensor. Aside from the fact that you are purposefully releasing toxic gases into the air, you are also driving your vehicle in such a manner as to cause more damage to the engine. You might have prevented this if you had decided to repair any faulty sensors immediately. It will not help you save money on repair charges if you put off replacing damaged sensors for a more extended time. Most significantly, driving a vehicle whose oxygen sensors are unable to monitor air intake and fuel delivery adequately puts your own life at risk while you are out on the road.


When your vehicle's oxygen sensor analyses the oxygen levels in your exhaust gases, it transmits this information to the Powertrain Control Module (PCM), which immediately calculates the proper air-to-fuel ratio for your engine. The sensor is positioned in the exhaust system and enables the fuel injection and engine timing to perform appropriately, aiding emissions management. The oxygen sensors provide data to the vehicle’s PCM to maintain the correct air-to-fuel ratio for your engine.

A defective or malfunctioning oxygen sensor can affect exhaust emissions and engine performance; therefore, there are things to check for before your oxygen sensor fails. When you encounter misfires, get terrible engine mileage, or have black emissions from your exhaust, you should check and repair your oxygen sensor before your vehicle experiences additional damage.

About A-Premium
Learn more about what makes A-
Premium a brand you can rely on.
Our Story