What Happens If an Oxygen Sensor Doesn't Work?

Oxygen sensors (also known as O2 sensors) are emission control devices that have been used on automobiles since 1980. The oxygen sensor serves several purposes in engine and emission management, including regulation of exhaust output and improving fuel economy.

Check Engine Light

Vehicles equipped with oxygen sensors will display a CEL (check engine light) on the instrument cluster when an oxygen sensor goes out.

Increased Emissions

Since oxygen sensors regulate vehicle tailpipe emissions, a faulty oxygen sensor will cause a vehicle to emit more pollutants than it normally does.

Reduced Fuel Economy

Oxygen sensors work to improve the fuel-air ratio in vehicles, which improves fuel economy. A faulty oxygen sensor could reduce fuel economy by 30 percent.

Rough Idle

If an oxygen sensor is faulty, a vehicle may exhibit a rough idle or run rough. The oxygen sensor works to maintain proper idle.

Failed Inspection

A faulty oxygen sensor could cause you to fail an inspection. Many states have inspections that check for emissions related problems; the faulty sensor would not allow the vehicle to pass the test.

References

• Oxygen Sensors
• Example of Emissions Test