Hi ALL!
I`m thinking of putting together a CHEAP (Led type indicator) AIR-FUEL MIXTURE gizmo for a carburated car which costs less than P200.

So now i just need an Oxygen sensor. I dont know much about O2 sensors to be honest, but i understand that a NARROW band O2 sensor is very common.

So, who knows the CHEAPEST available O2 sensor around? Preferrably the 4 terminal (heated type), otherwise even just a single or 3 wire (?) type. How are prices for UN-heated O2 sensors?

How about SURPLUS? How do i check them? (i know how to use a Multitester)

THANK YOU! Patrick