Computers and Control Systems: Description and Operation

1 General

IUMPR Statement:
The OBD II System of this test group is designed to comply with the provisions of CCR 1968.2, section (d)(3.2) requirements.

Overview:






Incrementing of numerator:

Front/Rear O2 sensor:
To increment the numerator a background monitor for sensor activity checks and response check will be considered. This ghost monitor will be related to the worst case times of each phase and step of the diagnosis.
a. If during this time the monitor conditions for the ghost monitor are met for the worst case condition (e.g number of amplitudes for slow sensor response), the system would have detected a failure. The numerator will be incremented.
b. If during this time the monitor conditions for the ghost monitor are not met, analogous to the normal function, the system would repeat the monitor. The numerator would not be incremented.
c. If during any repeated monitor the monitor conditions for the ghost monitor are met, for the worst case time, the system would have detected a failure. In this case the numerator will be incremented.

Catalyst efficiency:
When the monitor has been finished and the relevant O2 sensor monitors have been completed, the numerator will be incremented.

VVT:
The numerator will be incremented, if the monitoring conditions are several times fulfilled.

Incrementing denominator:
The following signals are used for denominator incrementing:
(Each sensor for this purpose is monitored either as out of range, signal or rationality check)

General denominator:






Evap denominator: