Oxygen Sensor

The oxygen sensor used in the EFI system is a closed-end Zirconia sensor placed in the exhaust gas stream. The sensor is constructed in such a way that the exhaust gases pass by the bottom of the sensor and atmospheric air is admitted at the top of the sensor. The Zirconia produces an electrical voltage when exposed to oxygen, similar to a small battery. By comparing the amount of oxygen present in the exhaust gases to the amount of oxygen in the atmosphere, the sensor produces a signal which is proportional to the oxygen concentration in the exhaust gases.

As the oxygen content of the exhaust gases increases relative to the surrounding atmosphere, a lean fuel mixture is indicated by a low voltage output. As the oxygen content decreases, a rich fuel mixture is indicated by a higher voltage output. The ECM interprets the electrical signal and adjusts the injector pulse width to maintain the air/fuel ratio close to 14.7 to 1.

NOTE: No attempt should be made to measure oxygen sensor voltage output. Current drain of conventional voltmeter could permanently damage sensor, shift sensor calibration and/or render sensor unusable. DO NOT connect jumper wire, test leads or other electrical connectors to sensor.