Toyota FJ Cruiser Oxygen Sensor

Also known as Lambda sensor, the oxygen sensor is an electronic sensor that is used to measure the amount of oxygen present in any liquid or gas. In automobiles, this sensor has the biggest hand in keeping the vehicle's performance at its best since based on the data it feeds to the ECU (Electronic Control Unit), it regulates the air fuel ratio which directly affects the power output from the engine.

The oxygen sensor is mounted on the exhaust manifold to measure the proportion of the unburnt oxygen as the exhaust gases exit from the combustion chamber. It is a way of measuring the air fuel mixture. It is with the help of this sensor the computer of a vehicle determines the air-fuel mixture to be rich (less oxygen) or lean (more oxygen). In modern cars, there is a secondary oxygen sensor in the downstream of catalytic converter for monitoring the vehicle emissions to abide by the emission laws.

The sensor has a vented cover on the end that screws into the exhaust manifold. Inside that cover, there is a zirconium ceramic bulb. A porous layer of platinum is coated on the outside of the bulb. e are 2 platinum strips inside the bulb that serve as electrodes. The sensor outside is exposed to the hot exhaust gases while the inside is ventilated to the outside atmosphere. The difference in oxygen levels in the engine exhaust and the atmosphere outside creates a voltage. This generated voltage is received by the ECU and it regulates the air-fuel mixture between rich and lean on basis of the generated voltage.

The oxygen sensors are located in the exhaust manifold. The one placed after catalytic converter is used to check the efficiency while keeping a check on the emissions. The sensor before the catalytic converter is used to calculate the air-fuel ratio.