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The
zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical
fuel cell called the
Nernst cell.
Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere.
Skinny - Sucks and Blows
This type does not generate its own voltage, but
changes its electrical resistance in response to the oxygen concentration. The resistance of the titania is a function of the oxygen partial pressure and the temperature.