Originally Posted by God,Country,FORD
I have no idea what you just said lol.. what is a hego? Sorry im a noob when i comes to emmisions stuff
hego means "heated exhaust gas oxygen"
when you mix gasoline and air together to burn them and make combustion happen, there are some important things that need to be right.
think of making chocolate milk by adding the powder (nestle quik) with white milk.
If you add too much powder it will be very thick, very "rich"
If you add too much milk it will be very thin, very "lean"
If you add just the right amount of milk with powder it will be chemically perfect or "stoic"
"stoic" for gasoline and oxygen is 14.7 parts oxygen with 1 part fuel. anything lower is rich, anything higher is lean.
Since the condition of the engine is always changing based on a million different things the sensor after the exhaust manifold is there to read the AFR, or Air to Fuel ratio to determine how close your truck is to 14.7. If it dosent see it bouncing around 14.7 then it makes an adjustment to what it needs to so that it can hopefully correct it some.
The oxygen sensor (hego) that is in the back BEHIND the cat simply looks to see that the Richness of the mixture is LESS RICH after the catalytic converter than it was before it went through the cat at the first hego. This tells your computer that the catalyst is present and working correctly.
There are more details around this but basically this is how any modern car works.