Many car owners only know something is wrong with their O2 sensor when a severe issue arises. Since this sensor directly works with your car engine, recognizing the early signs of a defective O2 sensor is vital. Today, Driverevolve will reveal 10 alarming symptoms and a temporary fix for bad O2 sensor (if you can’t head for pro services immediately). 

What Is An O2 Sensor?

Like D3 meaning in a car, O2 Sensor may render you scratch your head for the first heard! This device helps to measure your fuel-to-air mixture by gauging oxygen concentration in your emissions.

The O2 sensor informs the processor whether your fuel mixture is rich (insufficient O2) or lean (too much O2). Understanding this fuel-to-air proportion helps you take appropriate measures to operate your automobile appropriately.

How To Tell If the O2 Sensor Is Bad: 10 Alarming Signs  

If your vehicle exhibits any of the signs below, something might be wrong with your O2 sensor:

Rough Idling

Rough idling means your engine grinds loudly when you want to speed up. If you’re in the same situation, you should get your O2 sensor examined – it might be the underlying reason. 

Failed Emission Tests

Exhaust testing is an essential step in the entire automobile check-up procedure. It ensures that your car’s emission is in good condition and satisfies all regulatory criteria. When a vehicle fails emissions testing, its O2 sensor is more likely to be defective. Search for the best O2 sensor in Amazon here.

Fuel Efficiency Goes Down

If your vehicle’s fuel efficiency suddenly worsens, the issue may lie in your O2 sensor. The O2 sensor in your automobile aims to oversee the air-fuel ratio in the engine. When it’s defective, your car will fail to optimize fuel economy, leading to worse fuel efficiency.

Weak Engine Performance

Your vehicle’s engine may function poorly or even die entirely. While there are many explanations for weak engine performance, sometimes your faulty O2 sensor causes the problem (as it works directly with the engine). 

Thus, should your car's engine efficiency is poor; it's worth examining your O2 sensor to determine if it requires a replacement.
A bad oxygen sensor may weaken your engine performance. – Easy Car Electrics

Thus, should your car’s engine efficiency is poor; it’s worth examining your O2 sensor to determine if it requires a replacement.

Engine Noises

Strange engine sounds might also be a sign of a faulty O2 sensor. A defective sensor unit might make 3 kinds of sounds.

  • Knocking Sound: This sound is caused when the engine’s air/fuel combination is extremely lean. 
  • Pinging Sound: A defective O2 sensor will force your engine to run extremely rich, resulting in a pinging sound.
  • Rattling Sound: A rattling sound will appear if your sensor’s connector is loose.

Of note, try to tell apart noises as you may confuse clicking noises with rattling sounds, for example. This helps pinpoint the right culprits before tackling them.

Black Exhaust Fumes

A broken O2 sensor might result in black vehicle emissions. 

This mainly happens as your faulty oxygen sensor forces the engine to operate rich, indicating too much gasoline in the fuel-air mixture. This surplus gasoline will then turn the emission black.
Black emissions might be the result of your faulty O2 sensor. – Mechanic Base

This mainly happens as your faulty oxygen sensor forces the engine to operate rich, indicating too much gasoline in the fuel-air mixture. This surplus gasoline will then turn the emission black.

Another scenario is that your sensor is not collecting enough O2 due to an issue within the intake manifold. This might make your engine overheat and emit black exhaust emissions.

Rotten Egg Smell From The Exhaust

A defective O2 sensor causes a vehicle to exude a foul egg stench from its tailpipe. Indeed, it sends incorrect data that induce the engine to burn the gasoline wastefully, resulting in only a tiny portion of the fuel being turned into power. Never look down on such quirky and risky signals, regardless of spoiled egg or burning-rubber odor.

As a result, a considerable amount of the gasoline is converted into hazardous gases that exit your engine and affect the environment. These emissions contain sulfur dioxide, responsible for the putrid egg stench.

There are a few different explanations for why your vehicle emits this odor, but a faulty O2 sensor is still the most prevalent. In fact, our research shows that almost 75% of cars presenting this odor have a defective O2 sensor.

Overheating Engine

An overheated engine is also a sign of a failed oxygen sensor. The root problem is that your device cannot appropriately interpret the air/fuel combination. 

This can force your engine to operate rich or lean, resulting in overheating. Because of a defective sensor, your vehicle may even die in rare circumstances.
Your car might heat up excessively due to a bad O2 sensor. – Mechanic Base

This can force your engine to operate rich or lean, resulting in overheating. Because of this, your vehicle may even die in rare circumstances.

Sudden Catalytic Converter Failure

An abrupt catalytic converter collapse commonly accompanies a poor O2 sensor. Your oxygen sensor measures the air/fuel combination and delivers results to the controller. So, when it malfunctions, the air/fuel combination is imbalanced, which might heat up and force your catalytic converter to stall. If the negative symptom appears too many times, check the best catalytic converters to ensure your safety and also compliance with the law.

Flashing Check Engine Light

Another of the most frequent signs is a flickering check engine signal. This happens when your sensor incorrectly interprets the concentration of o2 in your exhaust manifold. Consequently, your engine cannot regulate the air-fuel combination correctly, potentially causing engine damage.

Can An O2 Sensor Cause A Misfire? 


If your o2 sensor fails, it may deliver inaccurate data to your engine’s processor, resulting in a misfire. However, unplugging it should solve the problem. The system will be back to normal by default.

Temporary Fix For Bad O2 Sensor (Complete Guide) 

A short-term repair for a bad O2 sensor involves circumventing it with a fake O2 sensor. However, since your O2 sensor is in the emissions control system, such an action isn’t advisable; and the eventual replacement of the sensor is inevitable.

Still, if you have no other options, follow these steps to fix your O2 sensor temporarily:

  • Get down to your undercarriage.
  • Remove the plug from the O2 sensors located under the car.
  • Loosen your O2 sensor in the counterclockwise direction with an O2 sensor disassembly device.
  • Install the fake O2 sensor and attach it to your sensor’s power socket.


Can you drive with a messed-up O2 sensor?

We urge people not to drive with a faulty oxygen sensor as the powertrain is not operating on the right fuel combination. Even though it may appear okay, if the powertrain excessively uses fuel, it could obstruct the catalytic converter.

Driving can be laborious and bumpy if the oxygen sensor is malfunctioning, as well as being inefficient with fuel and producing noxious exhaust. If the damaged sensor is left unaddressed for a considerable length of time, it could result in major issues with the motor and catalytic converter requiring significant expenditure to remedy or replace.

How Much Is Oxygen Sensor Replacement? 

According to the manufacturer and model of your automobile, changing your O2 sensor might be pricey. The O2 sensor cost runs between $50 and $200 on average. Service fees differ but commonly range from $50 to $100. Thus, it costs from $100 to $300 in total.

When Should I Replace My O2 Sensor?

When your car’s O2 sensor begins to show fault codes or fails emission testing, you should replace it.
Some experts advise changing your sensor whenever your car is tuned up, regardless of its present status. Preventive maintenance usually involves examining and changing the O2 sensor.

How many miles do I have to drive after replacing O2 sensor?

An important detail that you might not be aware of is that once you reset the car’s computer, you will have to drive for around 50 to 100 miles in order for it to take stock of all the sensors. As you drive, the computer will be keeping track of the data collected from the sensors.

Wrapping Up 

A temporary fix for bad O2 sensor isn’t impractical. However, if you have a faulty oxygen sensor, it is better to book a replacement. This sensor is manufactured from materials and technologies enclosed in a casing where repairs are tricky to execute. As a result, replacing the entire sensor is the best bet. Good luck!

For more knowledge of car parts, refer to our Fun Autopart section.

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