What does the 02 sensor do on a car?

Answer by  Kiwi48 (99)

The O2 sensor measures how much oxygen is in the fuel mix, and sends this information back to the car's computer so it can adjust the mixture appropriately. If it's not working properly, the mixture will be too lean or too rich. In extreme cases, this could cause a lot of expensive damage, such as harming the catalytic converter.

Answer by  Amber40 (24961)

An o2 or oxygen sensor basically monitors the amount of oxygen present in the exhaust. In turn the computer uses this information to determine and adjust the air/fuel ratio. Reducing emissions and helping the engine run at it's most efficient. If it is not working the computer won't know what to do. Leading to poor running and bad fuel economy.