9 Symptoms Of Bad Oxygen Sensor: Spot The Danger Signs Here

Symptoms Of Bad Oxygen Sensor

The oxygen sensor also called the O2 Sensor measures the unburned oxygen molecules in the exhaust gas. It prevents the engine from running lean or rich by adjusting the air-fuel ratio.

The oxygen sensor is located in the exhaust manifold before and after the catalytic converter. Over time, the oxygen sensor fails and shows a number of symptoms. A bad oxygen sensor can negatively affect your car’s performance.

If you think your oxygen sensor may be going bad, keep an eye out for symptoms. Fortunately, this article focuses on the symptoms of the oxygen sensor, which will help you know when to replace the oxygen sensor. In this powerful guide, you will learn the Nine horrible symptoms of bad oxygen sensors in simple and easy-to-understand language.

Related Post: What Is Oxygen Sensor In A Car

What Are the Symptoms Of a Bad Oxygen Sensor

Bad Oxygen Sensor Symptoms
Bad Oxygen Sensor Symptoms

When the oxygen sensor gets faulty, it does not send the input data to the ECU with accuracy, as a result, the car starts to show several signs. It is better to change the oxygen sensor every 60,000 to 90,000 miles. If you ignore changing the oxygen sensor, it might damage the catalytic converter.

For this reason, it is important to know what are the symptoms of bad oxygen sensors, so you could avoid further damage to the car. Below are the symptoms of a bad oxygen sensor.

Related Post: Where Is The Oxygen Sensor Located

9 Symptoms Of Bad Oxygen Sensor

  1. Check Engine Light
  2. Rough Engine Idle
  3. Reduced Gas Mileage
  4. Engine Missing
  5. Lack Of Engine Power
  6. Lean Mixture
  7. Rich Mixture
  8. Black Smoke
  9. Failing Emission Test

1. Check-Engine Light

Engine Check Light
Engine Check Light

A check engine light is one of the symptoms of a bad oxygen sensor. Whenever your car has a problem, the check engine light appears.

The check engine light will illuminate if the oxygen sensor is bad or its wiring has been cut, or it has a loose connector. You should have it checked by a professional to know the exact reason for the check engine light.

Related Post: Knock Sensor Check Engine Light On And Off

2. Rough Engine Idle

Tachometer Showing An Idling Engine
Tachometer Showing An Idling Engine

A rough engine idle is a symptom of a faulty oxygen sensor. A bad oxygen sensor makes the engine run roughly. A faulty oxygen sensor sends wrong data to the ECU, which affects the timing and air-to-fuel ratio, causing a rough or irregular idle.

3. Reduced Gas Mileage

Low Fuel
Low Fuel

Reduced gas mileage is also a sign of a bad oxygen sensor. A bad oxygen sensor affects gas mileage. The car uses air and fuel to produce power, when the oxygen sensor gets faulty, it sends wrong data to the car ECU, which miscalculates the information and disrupts the air-to-fuel ratio.

A bad oxygen sensor can cause to send a high amount of fuel, which leads to increased fuel consumption, as a result, the car uses a high amount of fuel and you feel reduced gas mileage.

4. Engine Missing

Car Not Starting
Car Not Starting

Engine missing can also be oxygen sensor symptoms of failure. Sometimes, a bad oxygen sensor causes a lean mixture. This lean mixture will cause to miss a combustion fire or misfire, especially when the engine is idle.

This lean mixture will cause engine hesitation during acceleration. Because, there is too little fuel in the combustion process, which causes the hesitant engine.

Related Post: What Are Bank 1 And Bank 2

5. Lack Of Engine Power

Engine
Engine

A lack of engine power can be a bad oxygen sensor symptom. A bad oxygen sensor will cause a lack of engine power. It causes the ECU to misread the information, and your car will have poor combustion.

A bad oxygen sensor leads to weak engine performance causing insufficient combustion. So, whenever you feel the does not run with full power, the reason might be a bad oxygen sensor.

6. Lean Mixture

Automobile Combustion Chamber
Automobile Combustion Chamber

A lean mixture is also a faulty oxygen sensor symptom. A bad oxygen sensor causes the ECU to misinterpret the input data, which sometimes leads to a lean mixture in the combustion chamber of the engine.

This lean mixture will cause several engine-related problems such as poor idle, engine shaking, engine stalling, etc.

7. Rich Mixture

Engine Piston
Engine Piston

A rich mixture may also oxygen sensor symptoms of failure. A faulty oxygen sensor may allow too much fuel into the combustion, causing a rich mixture.

Over time, the byproduct of combustion like sulfur, carbon, and oil ashes can deposit on the oxygen sensor, which keeps the oxygen sensor from sending correct signals to the car ECU, as a result, a high amount of fuel is sent to the combustion chamber, causes rich mixture.

Related Post: Oxygen Sensor: 1, 2, 3, 4 Wire O2 Sensor Wiring Diagram

8. Black Smoke

Black Smoke From Exhaust Gases
Black Smoke From Exhaust Gases

A cloud of black smoke is a symptom of a bad oxygen sensor. Black smoke exiting from the car exhaust is a sign that the fuel is not burned properly.

Bad oxygen sensors lead to over-fueling the combustion; as a result, all of the fuel will not burn, which causes black smoke and a rotten egg smell. It is because the amount of fuel present in the combustion chamber is higher compared to the air. The air burns fully but the fuel remains unburned, which leads to black smoke.

9. Failing Emission Test

Failing Emission Test
Failing Emission Test

A failed emission test can also be an oxygen sensor symptom of failure. Some countries make the emission test obligatory to control environmental pollution. That is the reason the emission test is carried out.

A bad oxygen sensor causes a failed emission test. It can lead to carbon monoxide and other toxic emissions, which are unhealthy for humans.

Related Post: What Causes An Oxygen Sensor To Fail

Frequently Asked Questions (FAQs)

How can you tell if an oxygen sensor is bad?


If your car is showing any of the following symptoms, it may have a bad oxygen sensor:
Check Engine Light
Rough Engine Idle
Reduced Gas Mileage
Engine Missing
Lack Of Engine Power
Lean Mixture
Rich Mixture
Black Smoke
Failing Emission Test

Can a bad O2 sensor cause engine damage?

A bad O2 sensor can cause engine damage by causing the engine to run too lean or rich. This can lead to increased temperatures in the combustion chamber, which can cause pre-ignition and knock. knock can cause cylinder damage and lead to engine failure.


Sign Up

    About The Author

    Leave a Comment

    Your email address will not be published. Required fields are marked *

    Scroll to Top