If indeed it does use such a sensor, here is an explanatory note from NGK:

Titania Sensors: The Titania element in these sensors does not produce a voltage like the Zirconia element. The property of the Titania element which allows for the detection of oxygen in the exhaust gas is its electrical resistance. The electrical resistance of the Titania element changes according to the concentration of oxygen in the exhaust gas. There is a big change in the resistance of the element when the fuel-ratio is 14.7. When a voltage is applied to the element in a voltage divider circuit, the output voltage changes with the resistance thus forming the voltage signal required to be processed by the ECU. As with the Zirconia sensor a low output voltage indicates a lean mixture and a high output voltage indicates a rich mixture. These voltages are used by the ECU for closed loop control.

As Titania sensors do not need air on one side of the element, they can be made smaller and are completely submersible. Due to their different properties Titania and Zirconia sensors should not be interchanged under any circumstance.