1995: OBD II emissions control system
Another technical highlight of the six-cylinder car was the new OBD (on-board diagnostics) II emissions monitoring system, which was used for the first time by a series production manufacturer. It facilitated early detection of faults or defects in the exhaust and fuel system. The extensive measures for reducing emissions were very effective on the 911 Turbo. To the great surprise of the experts, the turbo engine turned out to be the lowest emission series production engine in the world. The supercharged 993 was also the first biturbo with air mass control in automotive history. The OBD continually monitored the operation of the entire exhaust system with catalytic converters and oxygen sensors, the functioning of the tank ventilation system with activated charcoal filters, the air injection system and the fuel system. Misfiring was also recorded. At the time it was launched, OBD II was already mandatory in the USA, and other markets soon followed. OBD required a great deal of development work and an extremely complex engine management system.