Isuzu 1999 RODEO Workshop Manual page 876

connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the
fault.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the Diagnostic Trouble Code to
be set occurs. This may assist in diagnosing the
condition.
f Bank 1 HO2S 1/Bank 1 HO2S 2 Activity Test:
Ensure that the engine is fully warmed up.
Using a Tech 2, monitor Bank 1 HO2S 1 and Bank
1 HO2S 2 displays in "Neutral" while using the
Tech 2 IAC RPM control function to maintain a
mass air flow of 10 g/second. Compare the
amount of activity (frequency and amplitude) on
Bank 1 HO2S 1 to the activity on Bank 1 HO2S 2
over a 30 second period.
If the amount of activity on Bank 1 HO2S 2 is nearly as
great as the activity on Bank 1 HO2S 1, a problem exists.
Use the Diagnostic Trouble Code P0420 diagnostic chart.
If much less activity is noted on Bank 1 HO2S 2, the
system is functioning properly.
The "TWC Monitor Test Counter" displayed on the Tech 2
may be used to monitor the progress of the TWC
diagnostic. To complete the TWC diagnostic with a good
catalyst, the counter must be allowed to increment to 49
samples and roll over to 0 at least twice. A failed catalyst
will require three or more 50–sample tests to report a
failure.
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
7. Difficulty completing the Diagnostic Trouble Code
P0420 "Status This Ign." test may be encountered in
areas where test conditions cannot be maintained
easily, especially in urban areas. To minimize the
amount of driving required to complete the
Diagnostic Trouble Code P0420 "Status This Ign."
test, use the following procedure:
f Allow the engine to warm completely.
f With the vehicle in "Neutral," monitor the calculated
air flow on the Tech 2 and hold part throttle to
maintain a reading of over 12 g/second for at least 2
minutes. This will achieve the "warm catalyst"
required for running the test.
f Operate the vehicle in second or third gear to remain
in the Diagnostic Trouble Code P0420 test
conditions described in "Conditions for Setting the
Diagnostic Trouble Code" as much as possible. If
you must stop the vehicle, maintain the "warm
catalyst" criteria as follows:
– Place the vehicle in "Neutral."
– Hold part throttle to maintain a calculated air flow
reading of over 15 g/second for the duration of the
stop.
The "TWC Monitor Test Counter" displayed on the Tech 2
may be used to monitor the progress of the TWC
diagnostic. To complete the TWC diagnostic with a good
catalyst, the counter must be allowed to increment to 49
samples and roll over to 0 at least twice.
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