NOx sensing element(chip)
NOx sensor acts as oxygen sensor with extended functionality.
The sensing element is a ceramic chip that consists of a heating circuit, small passage leading into two cavities, oxygen pumping circuit and NOx decomposition circuit.
Nox sensing element in longitudial section view
Before operation, the ceramic chip is heated for
approximately 1,5 minutes for it to become functional.
As the exhaust gas enters the ceramic chip through
the small passage , at the first cavity all
the free oxygen molecules are pumped through the
electrolyte and remaining gasses diffuse into the
second cavity where NOx molecules are decomposed
and the resulting oxygen measured as a small electric
current. Additional circuit board is used
to convert the measured current to a signal which
is compatible with the Engine Control Unit (ECU)
communications protocol.
