Isuzu 1999 RODEO Workshop Manual page 793

6E1–166 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
damaged terminals,
connection, shorts to ground, shorts to battery positive
and open circuits.
f Faulty HO2S heater or heater circuit – With the ignition
ON engine OFF the HO2S voltage displayed on a Tech
2 should gradually drop to below 250 mV. If not,
disconnect the HO2S and connect a test light between
the HO2S ignition feed and heater ground circuits. If
the test light does not light, repair the open ignition feed
or sensor ground circuit as necessary. If the test light
lights and the HO2S signal and low circuits are OK,
replace the HO2S.
f Intermittent test – With the ignition ON monitor the
HO2S signal voltage while moving the wiring harness
and related connectors. If the fault is induced, the
DTC P0140 – O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
Step
1 Was the "On–Board Diagnostic (OBD) System Check"
performed?
2 1. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the engine above 1200 RPM for two
minutes.
Does the Tech 2 indicate Bank 1 HO2S 2 voltage vary
outside the specified value?
3 1. Ignition ON engine OFF review and record Tech 2
Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor "Diagnostic Trouble Code"
info for Diagnostic Trouble Code P0140 until the
Diagnostic Trouble Code P0140 test runs.
4. Note the test result.
Does the Tech 2 indicate Diagnostic Trouble Code
P0140 failed this ignition?
4 Check for a poor Bank 1 HO2S 2 high or low signal
circuit terminal connection at the Bank 1 HO2S 2
harness connector
necessary.
Did any terminals require replacement?
5 1. Ignition OFF.
2. Disconnect the PCM.
3. Check for poor Bank 1 HO2S 2 high or low signal
circuit terminal connection at the PCM and replace
the terminal if necessary.
Did either terminal require replacement?
6 Check continuity of the Bank 1 HO2S 2 signal circuits.
If either Bank 1 HO2S 2 signal circuit measures over 5
W, repair open or poor connection as necessary.
Was a Bank 1 HO2S 2 signal circuit problem found and
corrected?
poor terminal–to–wire
Action
and replace terminal(s)
HO2S signal voltage will change. This may help isolate
the location of the malfunction.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
3.If the Diagnostic Trouble Code P0140 test passes
while the Failure Records conditions are being
duplicated, an intermittent condition is indicated.
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.
Value(s)
— Go to Step 2
425–475 mV Go to Step 3
— Go to Step 4
if
— Verify repair
— Verify repair
— Verify repair
Yes No
Go to OBD
System
Check
Go to Step 4
Refer to
Diagnostic
Aids
Go to Step 5
Go to Step 6
Go to Step 7