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LEV/OBD ll-diagnosis

LEV/OBD ll-diagnosis

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 %

• similar warming-up status (below or above 71°C (160°F))


Enable criteria

Conditions that must be fulfilled before the diagnosis can be carried out.

Fault criteria

Once the enable criteria have been fulfilled, the diagnosis checks to see whether the fault criteria have been fulfilled.

Dependents

Once the fault criteria have been fulfilled, a number of other diagnoses must sometimes report OK before the diagnostic trouble code can finally be generated.

System reaction to a fault

Other 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.

Fault handling, throttle control

If a safety-related fault should occur in the throttle control, the throttle body will go into mechanical limp-home mode and CHECK ENGINE will immediately go on. The limp-home solenoid is subsequently activated each time the ignition is turned on. The fault will not repair itself and the car must be rectified in a workshop.

After repair, the diagnostic trouble code must be cleared first and then the limp-home mechanism reset.