Innova 3100 Owner's Manual page 45

The oxygen sensor must reach a temperature of at least 600-
650°F, and the engine must reach normal operating temperature,
for the computer to enter into closed-loop operation. The oxygen
sensor only functions when the computer is in closed-loop. A
properly operating oxygen sensor reacts quickly to any change in
oxygen content in the exhaust stream. A faulty oxygen sensor
reacts slowly, or its voltage signal is weak or missing.
The oxygen sensor is a "Two-Trip" monitor. If a fault is found on
the first trip, the computer temporarily saves the fault in its memory
as a Pending Code. The computer does not command the MIL on
at this time. If the fault is sensed again on the second trip, the
computer commands the MIL "On," and saves the code in its long-
term memory.
Secondary Air System Monitor - When a cold engine is first
started, it runs in open-loop mode. During open-loop operation, the
engine usually runs rich. A vehicle running rich wastes fuel and
creates increased emissions, such as carbon monoxide and some
hydrocarbons. A Secondary Air System injects air into the exhaust
stream to aid catalytic converter operation:
1. It supplies the catalytic converter with the oxygen it needs to
oxidize the carbon monoxide and hydrocarbons left over from
the combustion process during engine warm-up.
2. The extra oxygen injected into the exhaust stream also helps
the catalytic converter reach operating temperature more
quickly during warm-up periods. The catalytic converter must
heat to operating temperature to work properly.
The Secondary Air System Monitor checks for component integrity
and system operation, and tests for faults in the system. The
computer runs this Monitor once per trip.
The Secondary Air System Monitor is a "Two-Trip" monitor. If a
fault is found on the first trip, the computer temporarily saves this
fault in its memory as a Pending Code. The computer does not
command the MIL on at this time. If the fault is sensed again on
the second trip, the computer commands the MIL "On," and saves
the code in its long-term memory.
OBD 2
Learning More
OBD 2 MONITORS
43