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Why The Oxygen Sensor Fails?

By R&D
Published on December 25th, 2023

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To discuss the top five reasons why Oxygen Sensor fails.


The oxygen sensors read how much oxygen is present in the exhaust stream and tell the ECM if the fuel mixture is too lean/rich and maintain optimal combustion conditions. So the oxygen sensor is critical to modern car operation.

A bad oxygen sensor can cause rough and sluggish driving, as well as high pollution levels and poor fuel efficiency or cause catalytic converter problems that can be expensive. In addition, your engine’s timing, combustion intervals, and other vital functions can be adversely affected.

Below are the top reasons that cause the oxygen sensor to fail:

Long Time Usage

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The oxygen sensor as with all electrochemical sensors, loses sensitivity after long periods of use. Early oxygen sensors, on average, started to degrade at around two years. But now, these sensors can last up to five years. Aged oxygen sensors are one of the most common failures and can be a pain point for spending time and money to replace. Even if they don't fail, it's recommended to replace your sensors every 60,000 to 90,000 miles


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The zirconia cell of the oxygen sensor is very sensitive to contaminants. Sometimes, the oxygen sensors can be contaminated by elements from within the engine, such as:

  • Carbon buildup from a rich fuel mixture is frequent and causes many sensors to fail. In this case, the sensor develops a brownish color. Possible causes include a clogged air filter or a leaking or defective fuel injector.
  • A cracked cylinder head or a leaking cylinder head gasket may be let antifreeze into the combustion chamber. It can be very harmful to an oxygen sensor. The sensor will have a green whitish-brown color.
  • If the sensor has a whitish color, using an improper silicone gasket sealant on the engine can cause a failure.
  • Using leaded gasoline will harm an oxygen sensor and create a light pink color.

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High Temperature

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The oxygen sensors work in an excessive heat environment, so like the rest of the engine’s components, exposure to high temperatures may cause the sensor to deteriorate over time.

Irregular Maintenance

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Not performing or skipping the regular maintenance on your car, such as air filter replacement and spark plug replacement, can speed up the oxygen sensor failure quickly because more dirt and grime are gathering on your emissions system.

Using Low-Quality Gasoline

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The low-quality or non-recommended fuel can cause the oxygen sensor to fail quickly. It is because the low-quality fuel can produce more lead, sulfur, and oil ashes, which coat the oxygen sensor.

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