OBD II Diagnostics

OBD II diagnostics

Terms
Trip
Starting the engine and then driving in such a way that all components and functions included in the OBD II diagnostics have been monitored.

Driving cycle
Starting the engine.

Warming-up cycle
Starting the engine and then an increase in engine temperature of at least 22°C (40°F) to at least 71°C (160°F).

Similar operating conditions
- engine speed ±375 rpm
- engine load ±10 %
- same warm-up status (under or over 71 °C (160° & Phi;))

Enable criteria
Condition that must be fulfilled before diagnosis will be performed.

Fault criteria
Once the enable criteria have been fulfilled, the diagnosis will check whether the fault criteria have been fulfilled.

Dependents
Once the fault criteria have been fulfilled a number of other diagnoses must sometimes report OK as well before the diagnostic trouble code is finally generated.

System reaction to a fault
Certain measures will sometimes be taken once the fault criteria have been fulfilled.

OK report
The diagnosis can be included as a dependent for another diagnosis and must therefore report OK even if it is continuous. The OK report is also used in fault handling to decrement the fault counter.