2007 ISUZU KB P190 Circuit

6E–152 ENGINE DRIVEABILITY AND EMISSIONS
• Poor ECM to engine block grounds.
• Fuel pressure - The system will go lean if pressure is too low. The ECM can compensate for some
decrease. However, if fuel pressure is too low, a
Diagnostic Trouble Code P0131 may be set. Refer to
Fuel System Diagnosis.
• Lean injector(s) - Perform “Injector Balance Test.”
• Vacuum leaks - Check for disconnected or damaged vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV
system. • Exhaust leaks - An exhaust leak may cause outside
air to be pulled into the exhaust gas stream past the
HO2S, causing the system to appear lean. Check for
exhaust leaks that may cause a false lean condition
to be indicated.
• Fuel contamination - Water, even in small amounts, can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition. For
the procedure to check for fuel contamination, Refer
to Fuel System Diagnosis.
Diagnostic Trouble Code (DTC) P0131
O
2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
Step Action Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check” performed?
—Go to Step 2Go to
On Board
Diagnostic
(OBD) System Check
2 1. Connect the Tech 2. 2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0: Diagnostic Trouble Code”.
Is the DTC P0131 stored as “Present Failure”? — Go to Step 3Refer to
Diagnostic Aids and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”. 2. Select “Clear DTC Information” with the Tech2 andclear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed This Ignition” in “F2: DTC Information”.
Was the DTC P0131 stored in this ignition cycle? — Go to Step 4Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the O
2 sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
— Verify repair Go to Step 5
5 Using the DVM and check the O
2 sensor circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the O
2 sensor connector.
3. Check the circuit for short to heater ground or ground circuit.
Was the DVM indicated specified value?
Approximatly 450mV Go to Step 7Go to Step 6
C56(J2) E77
31 216
V
21
E77

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–153
6 Using the DVM and check the O2 sensor circuit.
Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM disconnected) Refer to 6E-88 page.
3. Disconnect the O
2 sensor.
4. Check the circuit for short to heater ground or short to ground circuit.
Was the problem found?
Breaker box is not available: 1. Ignition “Off”, engine “Off”.
2. Disconnect the O
2 sensor connector and ECM
connector.
3. Check the circuit for short to heater ground or short to ground circuit.
Was the problem found?
—Repair faulty
harness and verify repair Go to Step 15
7 Using the DVM and check the O
2 sensor circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the the O
2 sensor connector.
3. Check the circuit for short to heater ground circuit.
Was the DVM indicated specified value?
No continuity Go to Step 9Go to Step 8
8 Repair the short to heater ground circuit. Was the problem found? — Verify repair Go to Step 15
Step
Action Value(s) Yes No
J2-6J2-21
Breaker BoxJ2-31
ΩΩΩ
Ω
C-56(J2)
2
16
ΩΩ
C-56(J2)
2 1
631Ω
Ω
O2 Sensor
423
2
Ω
3
1
Ω
1

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–155
DIAGNOSTIC TROUBLE CODE (DTC) P0132 O2 SENSOR CIRCUIT HIGH
VOLTAGE (BANK 1 SENSOR 1)
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine control module (ECM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal and low circuits. The oxygen
sensor varies the voltage within a range of about 1000
mV when the exhaust is rich, down through about 10
mV when exhaust is lean. The ECM constantly monitors
the HO2S signal during “Closed Loop” operation and
compensates for a rich or lean condition by decreasing
or increasing injector pulse width as necessary. If the Bank 1 HO2S 1 voltage remains excessively high for an
extended period of time, Diagnostic Trouble Code
P0132 will be set.
Diagnostic Aids
Check the following items:
• Fuel pressure - The system will go rich if pressure is too high. The ECM can compensate for some
increase. However, if fuel pressure is too high, a
Diagnostic Trouble Code P0132 may be set. Refer to
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0132 A O
2 Sensor Circuit High Voltage (Bank 1
Sensor 1) 1. No DTC relating to MAP sensor, TPS,
EVAP purge, ECT sensor, CKP sensor,
VSS, injector control circuit and ignition
control circuit.
2. Engine coolant temperature is more than 60 deg. C.
3. O
2 sensor bank 1 output voltage is more
than 952mV in “Closed Loop” condition. “Open Loop” fuel control.

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ISUZU KB P190 2007

6E–156 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis.
• Perform “Injector Balance Test” - Refer to Fuel System Diagnosis.
• Check the EVAP canister for fuel saturation - If full of fuel, check canister control and hoses. Refer to
Evaporative (EVAP) Emission Control System.
• Check for a leak in the fuel pressure regulator diaphragm by checking the vacuum line to the
regulator for the presence of fuel. • An intermittent TPS output will cause the system to
go rich due to a false indication of the engine
accelerating.
• Silicon contamination of the HO2S can also cause a high HO2S voltage to be indicated. This condition is
indicated by a powdery white deposit on the portion
of the HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.
Diagnostic Trouble Code (DTC) P0132
O
2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
Step Action Value(S) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check” performed?
—Go to Step 2Go to
On Board
Diagnostic
(OBD) System Check
2 1. Connect the Tech 2. 2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0: Diagnostic Trouble Code”.
Is the DTC P0132 stored as “Present Failure”? — Go to Step 3Refer to
Diagnostic Aids and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”. 2. Select “Clear DTC Information” with the Tech2 andclear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed This Ignition” in “F2: DTC Information”.
Was the DTC P0132 stored in this ignition cycle? — Go to Step 4Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the O
2 sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
— Verify repair Go to Step 5
5 Using the DVM and check the O
2 sensor circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the the O
2 sensor connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Approximatly 450mV Go to Step 7Go to Step 6
C56(J2) E77
31 216
V
21
E77

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–157
6 Using the DVM and check the O2 sensor circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the O
2 sensor connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specifed value?
Less than 1V Go to Step 15Repair faulty
harness and verify repair
7 Using the DVM and check the O
2 sensor circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the the O
2 sensor connector.
3. Check the circuit for short to heater power supply circuit.
Was the DVM indicated specified value?
No continuity Go to Step 9Go to Step 8
8 Repair the short to heater power supply circuit. Was the problem found? — Verify repair Go to Step 15
9 1. Using the Tech 2, ignition “On” and engine “On”. 2. Monitor the “Manifold Absolute Pressure” in thedata display.
Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration? — Go to Step 11Go to Step 10
10 Remove the MAP sensor and check for the following conditions.
• Objects blocking the air cleaner.
• Objects blocking the MAP sensor.
• Objects blocking the throttle valve.
• Vacuum leaking at intake duct.
• Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found? — Verify repair Go to Step 11
11 1. Using the Tech 2, ignition “On” and engine “On”. 2. Select the “Miscellaneous Test” and perform the“IAC Control” in the “IAC System”.
3. Operate the Tech 2 in accordance with procedure.
Was the engine speed changed, when the IAC valve
is operating step by step? — Go to Step 13Go to Step 12
Step
Action Value(S) Yes No
12
VV
E77
1
24
1234
O2 Sensor

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–159
DIAGNOSTIC TROUBLE CODE (DTC) P0134 O2 SENSOR NO ACTIVITY
DEFECTED (BANK 1 SENSOR 1)
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine control module (ECM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) high and low circuits. The oxygen
sensor varies the voltage within a range of about 1000
mV when the exhaust is rich, down through about 10
mV when exhaust is lean. The ECM constantly monitors
the HO2S signal during “Closed Loop” operation and compensates for a rich or lean condition by decreasing
or increasing injector pulse width as necessary. If the
Bank 1 HO2S 1 voltage remains at or near the 450 mV
bias for an extended period of time, Diagnostic Trouble
Code P0134 will be set, indicating an open sensor
signal or sensor low circuit.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0134 A O
2 Sensor Circuit No Activity Detected
(Bank 1 Sensor 1) 1. No DTC relating to MAP sensor, TPS,
EVAP purge, ECT sensor, CKP sensor,
VSS, injector control circuit and ignition
control circuit.
2. Engine coolant temperature is more than 60 deg.C.
3. Engine run time is longer than 40 seconds.
4. Mass air flow is more than 7g/s.
5. O
2 sensor bank 1 output voltage is
between 300mV and 600mV. “Open Loop” fuel control.

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ISUZU KB P190 2007

6E–160 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
• Poor connection or damaged harness - Inspect the harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
Diagnostic Trouble Code (DTC) P0134
O
2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
Step Action Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check” performed?
—Go to Step 2Go to
On Board
Diagnostic
(OBD) System Check
2 1. Connect the Tech 2. 2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0: Diagnostic Trouble Code”.
Is the DTC P0134 stored as “Present Failure”? — Go to Step 3Refer to
Diagnostic Aids and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”. 2. Select “Clear DTC Information” with the Tech2 andclear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed This Ignition” in “F2: DTC Information”.
Was the DTC P0134 stored in this ignition cycle? — Go to Step 4Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the O
2 sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
— Verify repair Go to Step 5
5 Using the DVM and check the O
2 sensor circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the O
2 sensor connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
Approximatly 450mV Go to Step 7Go to Step 6
C56(J2) E77
31 216
V
21
E77

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–161
6 Using the DVM and check the O2 sensor circuit.
Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM disconnected) Refer to 6E-88 page.
3. Disconnect the O
2 sensor.
4. Check the circuit for open circuit.
Was the problem found?
Breaker box is not available: 1. Ignition “Off”, engine “Off”.
2. Disconnect the O
2 sensor connector and ECM
connector.
3. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and verify repair Go to Step 13
7 1. Using the Tech 2, ignition “On” and engine “On”. 2. Monitor the “Manifold Absolute Pressure” in thedata display.
Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration? — Go to Step 9Go to Step 8
8 Remove the MAP sensor and check for the following conditions.
• Objects blocking the air cleaner.
• Objects blocking the MAP sensor.
• Objects blocking the throttle valve.
• Vacuum leaking at intake duct.
• Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found? — Verify repair Go to Step 9
9 1. Using the Tech 2, ignition “On” and engine “On”. 2. Select the “Miscellaneous Test” and perform the“IAC Control” in the “IAC System”.
3. Operate the Tech 2 in accordance with procedure.
Was the engine speed changed, when the IAC valve
is operating step by step? — Go to Step 11Go to Step 10
Step
Action Value(s) Yes No
J2-6J2-21
Breaker Box
E-77
21
ΩΩ
1
2
21
6C56(J2) E77

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ISUZU KB P190 2007