What Is An Oxygen Sensor And Why Is It Important?

Oxygen (O2) sensors are critical emissions system components. They determine how efficiently and how cleanly the engine is running. Any malfunction of an oxygen sensor can result in poor drivability, reduced fuel economy, or excessive tailpipe emissions. If you've ever experienced oxygen sensor problems, you know how frustrating the issue can be. If the topic is new to you, this post is tor you!

What Is An Oxygen Sensor?

Mazda oxygen sensor

An oxygen sensor measures the amount of oxygen in the exhaust stream as the engine is running. As the engine burns fuel, the oxygen content determines if the engine is running rich (too little oxygen) or lean (too much oxygen). The engine control unit (ECU) uses this information to adjust the air/fuel ratio for efficient combustion. Newer cars typically have two oxygen sensors per exhaust outlet. One sensor is mounted on the exhaust manifold. The other sensor is mounted on the exhaust pipe after the catalytic converter. The ECU compares data from the two sensors to calculate how well the catalytic converter is functioning.

Why Is An Oxygen Sensor Important?

The ECU requires constant O2 sensor data to adjust the delivery of fuel to the engine under all driving conditions. Oxygen sensor data is critical for several reasons, including:

  • Improving fuel economy
  • Reducing tailpipe emissions
  • Adjusting for engine operating temperature
  • Controlling variable valve timing
  • Compensating for altitude changes

How Does An O2 Sensor Work?

An O2 sensor produces its own voltage when exposed to hot exhaust gases (around 600°-650°F). If the air/fuel ratio is lean (too little fuel) the voltage reads low. If the air/fuel ratio is rich (too much fuel) the voltage reads high. Most newer cars have heated oxygen sensors. This allows the O2 sensors to monitor oxygen levels before the engine reaches operating temperature. 

How Long Do Oxygen Sensors Last?

Replace mazda 02 sensor

Modern O2 sensors should last up to 100,000 miles. An engine malfunction may shorten the life of oxygen sensors due to contamination. This can include:

  • Leaking fuel injectors introduce too much fuel into the exhaust.
  • Oil blow-by from internal engine wear enters the exhaust.
  • Coolant from a blown head gasket enters the combustion chamber.

Otherwise, age-related oxygen sensor failures may appear beyond 100,000 miles. The first sign of an O2 sensor problem is usually the check engine light turning on, followed by drivability issues. The operation of an oxygen sensor is complex. When it malfunctions, stored trouble codes will give an indication of what the sensor is doing and why.  Learn how to tell if your oxygen sensor is bad

O2 Sensors From REALMazdaParts.com

REAL Mazda Parts only carries OEM Mazda parts that are tested to meet the specifications of Mazda. Shop here and you get more than genuine factory Mazda parts - you get wholesale pricing and fast, affordable shipping. Shop with us because:

  • We have the right OEM oxygen sensors for your specific Mazda vehicle. 
  • All OEM parts are backed by Mazda's manufacturer warranty.
  • If you have any questions, we’re always here to help. Please contact us