Repair 7

How Do O2 Sensors Work on Automobiles

Automotive oxygen sensors, or 02 sensors, are little electronic devices that measure the amount of oxygen in a cars exhaust, helping to reduce pollution and increase fuel economy. Oxygen sensors were first implemented in 1976 when automaker Volvo engineered them into the exhaust system of a car called the 240.

Basic Function

O2 sensors are designed to help regulate emissions from the exhaust. They are often located in the exhaust manifold; their basic function is to monitor the amount of unburned oxygen that passes through a cars exhaust system. O2 sensors send messages to the automobiles computer telling it if the fuel mixture is burning too much or not enough oxygen.

Significance

In the early 1980s California required that all new cars sold in the state must have oxygen sensors. Several other states followed suit, and by the late 1990s O2 sensors are required equipment on all automobiles sold in the United States.

Design

O2 sensors are equipped with a zirconium ceramic bulb located within a vented cover that screws into the exhaust manifold. With a coated layer of porous platinum, the bulb also has two strips of platinum inside to act as electrodes.

How They Work

As hot gases pass through the cars exhaust system, they pass through the vented end of the oxygen sensor. The ceramic bulb on the O2 sensor gets exposed to the hot gas and experiences an increase in voltage output that represents the difference in oxygen levels between the exhaust and the outside air. A higher release of voltage indicates a great difference in these two factors. The automobiles computer reads this information and compensates for the lopsided ratio accordingly by leaning the fuel mixture with either the carburetor or throttle-body, depending on type of vehicle it is.

Warnings

O2 sensors, like all automobile components, wear out with age. Dirt, grease and grime are the most common factors that result in damaged or faulty oxygen sensors on automobiles. Driving with a faulty O2 sensor will cause increased fuel consumption as well as higher outputs of exhaust pollution than with a working O2 sensor.