What does the O2 sensor do?
The O2 sensor measures the unburned oxygen in the exhaust gasses coming out of the engine. The engine’s computer varies the air/fuel mixture depending on what the O2 tells it. Over time, with age, the O2 sensor slows down, giving the computer bad information. The computer then sets the wrong mixture, often leading to a rich-running engine that wastes gas and pollutes the atmosphere. The over-rich fuel mixture will also lead to premature failure of your catalytic converter. Considering how many problems a bad O2 sensor can cause, there are some experts who recommend replacing the O2 sensor as a preventive maintenance item, usually every 60,000 miles. Considering that a sluggish O2 sensor can easily cost you an extra $100 a year in poor gas mileage, it may not be a bad investment.
