In the old days - say the late 1930's - a typical four-cylinder engine might put out 40 horsepower and get 18 MPG. Today, even a small-block V8 can get up to 24 MPG while putting out 200 horsepower, and 150 HP V6 engines that get 30 MPG are common. This is in large part due to a high-tech fuel intake and exhaust system that work together to make the most efficient use of every precious drop of gasoline.

The stars of this system are the fuel injectors, which have replaced the old carburetor, and the oxygen sensor, which has taken over the function of a choke knob. The Subaru Forester Oxygen Sensor works by analyzing exhaust for its oxygen content.

This data is then relayed to the fuel injectors, which then adjust the ratio of fuel to air for the current driving conditions. In the old days, the fuel/air mixture was adjusted by hand using the choke knob. It took a lot of experience and a fair amount of intuition to achieve just the right mixture - and the efficiency was nowhere near today's levels. Your Subaru Forester actually has two oxygen sensors - one in front and one in back. Either Subaru Forester Oxygen Sensor - or "O2 Sensor" - may be responsible for the illumination of that "Check Engine" light on your dashboard if it has become defective. Fortunately, the Subaru Forester Oxygen Sensor is not expensive, costing well under one hundred dollars, and is fairly easy to replace.When its time for a new Subaru Forester Oxygen Sensor, come visit us for the lowest prices online - as well as free shipping! Order online or by phone!