Oxygen Sensor Design and Operation
 Oxygen sensors have a center ceramic element made up of Zirconium Oxide, Alumina and Yttrium Oxide. The operation of the sensor is based upon the fact that the ceramic material is porous and permits diffusion of the oxygen that is present in the air. The inner and outer surfaces of the element are coated with platinum, which become the positive and negative electrodes. The inner electrode is exposed to the outside air and forms the positive terminal. The outer electrode, which is exposed to the exhaust stream, makes up the negative terminal. A Spinel coating is applied to the outer platinum electrode to prevent solid particles present in the exhaust gas from eroding the platinum layer.
Oxygen Sensor Components and Assembly
O2 Sensor Cut-A-Way
The illustration to the right shows the sensors designed and manufactured by Standard Motor Products. The center element, or thimble, is held in a threaded mounting shell and a protective shield is placed over the tip. A seal prevents the exhaust gasses from blowing past the threaded shell to the outside air. A vented sleeve is attached to the top of the thimble which holds the electrical terminals and allows outside air to enter the inner section of the thimble.
  • Wire Harness
  • Rubber Boot
  • Terminals
  • Terminal Blocks
  • Sleeve
  • Talc Seal
  • Gasket
  • Shell
  • Heater
  • Element
  • Shield
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