oxygen sensor part 2

What does a Oxygen Sensor do

The Oxygen sensor was design to tell the ECU when there is oxygen in the exhaust gas, so the ECU can adjust the mixture close to Lambda 1 (14.7:1) as well as the purpose to protect the catalytic converter (CAT).O2 sensors becomes unresponsive and slow to change voltage after a while,a slow or unresponsive O2 sensor will result in consuming more fuel and a lag in engine performance when accelerate. It is recommended to change them every 60,000-100,000km,some newer cars the engine check light will come on when they need changing. Oxygen Sensor is passive sensor which does not require power to run, most outputs its own voltage.Leaded fuel and non O2 sensor safe silicone gasket makers (If it smells like vinegar it's not O2 safe) will destroy the O2 Sensor.

How it works
Oxygen sensors need to be at 500-600 degrees for it to start working (when O2 sennsor is cold its open loop
when 02 sensor is hot n working its close loop).This is why some O2 sensor have 4 wires, they has a heater core to heat them up this brings them up to working condition as soon as possible so the car will function at its  properly.Some have a earth wire directly to EC to stop interference because the voltage is so small a earth wire is to be presise.
-If 02 sensor is not working it goes lean or stuck at a voltage.
-If a air leak in the exhaust pipe before the 02 sensor it  goes lean

0v lean
0.45 ideal voltage
0.9v rich


Types of O2 sensor
- Zirconia
switching type DC volt
-Wideband
5-7 wire  basicly 2 02 sensors together so 2 signal, 2 ground, 2 heaters and a ground

-Titania switching (narrow-band lambda)
Unlike the other 2 this does not create its own voltage instead it changes its resistance




Numbers of O2 sensor in a car.
-Newer cars have 2 O2 sensor, before the CAT (up stream) for the mixture lamda and after the cat (down stream) to make sure if the cat is working.
-V style engine have a O2 sensor per bank so a V12 would have 2 left and 2 right.