1. Structure of oxygen sensor
An oxygen sensor is a solid electrolyte galvanic cell. Electrolyte is zirconium oxide, which is the same material synthetic diamonds are made from. This material is stabilized with a rare element called Yttria. The cell (thimble or flat plate) is then coated with pure platinum, which acts as a conductor/electrode (like battery plates).

2. Work principle of the oxygen sensor
The sensor works as a result of the varying quantities of oxygen in the exhaust verses the amount in the atmosphere. Voltage is produced by the difference in the two amounts. If the amount of oxygen in the exhaust is closer to the amount in the air, the engine is lean and the voltage is low (under 250mv). If the engine is rich the voltage is high (about 950mv).

3. Control Principle of the oxygen sensor
• Voltage range: [ 0.1, 0.85]
• Discrete control.
• Setting up two thresholds 0.3, 0.6
V=0.3V, shows the mixed gas is too thin. ECU will inform the oil vapor pump to spout more oil.
V=0.6V, shows the mixed gas is too thick. ECU will inform the oil vapor pump to spout less oil.
Between 0.3-0.6, PID will be adopted to adjust the engine reach the best functional mode.

4. Performance of the oxygen sensor
• Poison
Other stabilizing agent should be used in gasoline.
Pb. S. P. Si, and so elements will not be used in the course of production.
• Signal
solve in the formula and techniques of adulterating, electrode and protective cove

5. Function of oxygen sensor
The oxygen sensor monitors the engines air to fuel ratio by measuring the amount of free oxygen in the exhaust. It reports this information to the engine control unit or ECU. Approximately every 10 milliseconds the ECU uses this information to make corrections to the air to fuel mixture for maximum efficiency. Also it can reduce the displacement of harmful gas, such as CO, HC, NOX as to save energy source furthest.

6. Sorts of oxygen base sensors
The base sensor design and elements vary greatly. Below is a list of the most widely used base sensors.
• Single wire unheated standard zirconia sensors.
• Two wire unheated standard zirconia sensors.
• Three wire heated standard zirconia sensors.
• Three wire heated titania sensors.
• Four wire heated standard zirconia thimble type isolated ground sensors. Within this sensor group there are multiple heater types.
• Four wire heated standard zirconia thimble type case ground sensors. Within this sensor group there are multiple heater types.
• Four wire heated standard zirconia planar type isolated ground sensors. Within this sensor group there are multiple heater types.
• Four wire heated zirconia thimble type air fuel ratio sensors.
• Four wire heated zirconia planar type air fuel ratio sensors.
• UEGO five wire wide air fuel ratiosensors.

7. Factors to damage oxygen sensor
Natural aging, shock from accidents, antifreeze poisoning, excessive oil consumption or leakage, silicone poisoning due to incorrect use of silicone gasket sealers, etc.

8.Ways to know oxygen sensor’s performance
Usually the check engine light is illuminated if there is a failure of the sensor. Sensors that are not performing at peak efficiency may not cause the check engine light to illuminate, but will usually cause a rich shift in air fuel ratio and probably damage the catalyst.

9. Location to be assembled for oxygen sensor
Oxygen sensors are located within the exhaust stream. There is at least one oxygen sensor located before the catalytic converter. Typically one in each exhaust manifold. These monitor the air fuel mixture of the engine. Depending on the exhaust design there is also one or two located after the catalytic converter to monitor its effectiveness.

10. Wire colors meanings of oxygen sensor?
Typically the colors depict the connections inside the sensor; however, various manufacturers choose different colors. For example; some manufacturers use white wires for the heater & others use black.

11. Ways to test oxygen sensors
The best method is to use a scan tool and a portable DSO (Digital Storage Oscilloscope) to monitor the sensor switching characteristics. Connect the scan tool to the ALDL (assembly line diagnostics link) connector on the vehicle. This link allows you to monitor the performance of all sensors including the oxygen sensor.

12.Useful Life
• Heat chock resistant ability( or Heat oscillation).
Increase toughness.( adulterating, techniques )
• Hydrolyze
• 450°<T<550°, easy to hydrolyze and produce zirconium hydroxide. Symptom: frothing, volume increasing, electrode chipping off, leading to no signal.
zirconium hydroxide would be cracked if serious.
Solution: Adulterating, increasing the powder’s degree of fineness, decreasing the temperature of sinter.