Titanium (Titania) Sensors

Titanium Sensors differ in construction from the more common Zirconia type, and offer several advantages to the engine management system.

Figure 10 - Cutaway diagram of a titania sensor

Titanium sensors do not generate a voltage as the Zirconia type do. Instead, the resistance of the sensing element changes in response to the Oxygen present in the exhaust gases. The ECU uses slightly different circuitry to sense the changes which uses a precision voltage reference, and the two types are not interchangeable. However, the output curve of the Titania sensor is very similar to the Zirconia.

There is no need for a pocket of atmospheric reference gas with this type of sensor, hence the absence of a vent. This is important for off-road vehicles where mud and other debris may splash the exhaust system. The sensor casing can be physically smaller, stronger, and it has a faster reaction time than the Zirconia type, which is why it is a functionally superior sensor. However, it is still a narrowband type of sensor.

Titania sensors were initially used because they are less susceptible to lead poisoning than the Zirconia types. They are, however, more susceptible to anti-freeze poisoning than the Zirconia types. However the other advantages of the sensor (faster response times, more efficient packaging) led some ECU designers to use this type of sensor.

BMW used the Siemens engine management system for the later 3.2 M3's during the 1990s which utilises a Titanium sensor for reasons of being better suited to the high-performance engine ECU, which gives the unit its phenomenal power/weight output. The system was also used on other 6 cylinder BMW's. Two types of sensor are available from Lambdapower each with slightly different mechanical construction, but identical electrical performance. The different types can be distinguished by the different sensor casings - one is smooth, the other stepped.

Vauxhall also used a Siemens ECU during the Nineties, and again for reasons of high performance a Titanium sensor was specified. NGK are the OE manufacturer of all these items because their laboratories developed them, therefore Bosch do not produce a Titanium sensor.

Some Lucas-ECU equipped vehicles also use a Titania sensor, notably V8 Land Rovers and Range Rovers and TVR's using the same engine management.