Why is the O2 sensor on my Ford Focus bad?
Why is the O2 sensor on my Ford Focus bad? Your Focus’s oxygen sensors are responsible for helping to keep your engine running at optimal efficiency. The engine management computer uses the data from all of the O2 sensors to keep the air/fuel mixture optimized. A bad oxygen sensor can affect the mixture greatly. How does the O2 sensor in an engine work? Measurement of the oxygen level in the exhaust provides a good gauge of the fuel to oxygen ratio. The level of oxygen measured is sent to the engine control unit (ECU) for analysis. If the fuel mixture...