Titanium dioxide lambda sensor

Titanium dioxide lambda sensors were used as a regulating and as a diagnostic sensor, depending on the vehicle. This technology is no longer used in original equipment.
Titanium dioxide lambda sensor

The titanium dioxide lambda sensor is also a discrete-level sensor. Titanium dioxide has a special characteristic: The electrical resistance changes proportionally to the oxygen content in the exhaust air. In the process, the measured resistance provides information about the operating state of the engine.

The titanium dioxide lambda sensor is distinguished by the following characteristics:

  • Sturdy and compact design
  • Short response time
  • No reference air required
  • Operating temperature reached quickly

These sensors were used as a regulating and as a diagnostic sensor, depending on the vehicle. This technology is no longer used in original equipment.

Method of operation of the titanium dioxide lambda sensor

A titanium dioxide element changes its electrical resistance proportionally to the partial oxygen pressure in the gas mixture.
Method of operation of the titanium dioxide lambda sensor

A titanium dioxide element changes its electrical resistance proportionally to the partial oxygen pressure in the gas mixture. With a high oxygen concentration (λ > 1) the titanium dioxide is less conductive; with a low oxygen concentration (λ < 1) it is more conductive.

If a voltage is now applied to the element, the output voltage changes according to the hydrogen concentration in the exhaust. The operating temperature of these lambda sensors is around 700 °C. The sensor can only be destroyed at temperatures above 850 °C.

An additional advantage of this type of sensor: The titanium dioxide sensor does not require any outside air as a reference and is therefore smaller.

Cable assignment

Titanium dioxide lambda sensors produced by NTK always have four cables. For all types the (-) signal is black, the (+) signal is yellow and the connection for the heating element (-) is white.

Only the cable for the heating element (+) may differ in colour: For type 1 lambda sensors this cable is red; for type 2 it is grey.

Titanium dioxide lambda sensor Type I and Type II cable assignment