High pressure and temperature exhau

High pressure and temperature exhaust gases leaving the engine cylinder during the exhaust stroke, travel through the exhaust manifold and come in contact with the oxygen sensor placed before the catalytic converter. The sensing element at the front of the sensor consists of a zirconium dioxide sensing element enclosed within a steel shell. The sensing element is further connected to platinum electrodes and wire leads down the line.
Exhaust gas consisting of oxygen molecules, come in contact with the sensing element after flowing through the holes on the steel shell. Outside air is made to flow through the gaps between the connecting cables. This air is then heated to enable the ions to produce voltage. The difference in concentration of oxygen molecules in the exhaust gas and the ambient air drives the oxygen ions from higher to lower concentration.