2007 ISUZU KB P190 engine

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-161
DTC P0401 (Flash Code 93)
Circuit Description
The ECM controls the EGR valve opening based on the
engine running condition and by controlling the EGR
solenoid. The EGR valve position is detected by the
position sensor, and relayed to the ECM. When the
proper enabling conditions are met, the ECM will open
the EGR valve while monitoring the mass air flow
(MAF) signal. An expected MAF difference should be
detected between the closed and open positions. If the
ECM detects the MAF difference less than expected,
this DTC will set. This DTC will only run once per
ignition cycle within the enabling conditions.
Condition for Running the DTC • DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0122, P0123, P0403,
P0404, P0405, P0406, P0500, P0501, P0652,
P0653, P0698, P0699, P2100, P2101, P2102,
P2103, P2227, P2228 and P2229 are not set.
• The battery voltage is between 10 to 16 volts.
• The ignition switch is ON. Condition for Setting the DTC
• The ECM detects that the MAF amount is not within the calculated range during the EGR flow
test. This indicates insufficient amount of EGR
flow.
Action Taken When the DTC Sets • The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM limits fuel injection quantity.
• The ECM inhibits pilot injection.
• The ECM inhibits cruise control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• A sticking or intermittently sticking the EGR valve may set this DTC.
Circuit/ System Testing DTC P0401
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine and warm up as necessary (allow engine coolant temperature to reach at
least 60 °C [140 °F]).
4. Perform the EGR Solenoid Control with a scan tool.
5. Command the Desired EGR Position Increase or Decrease while observing the Mass Air
Flow (MAF) Sensor parameter with a scan
tool.
Does the MAF Sensor parameter decrease by at
least 0.5 volts when the Desired EGR Position is
commanded from 0 to 90%? —
Go to Diagnostic Aids Go to Step 3

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ISUZU KB P190 2007

6E-162 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
31. Inspect the following conditions:
• An EGR valve gasket that is missing ordamaged
• A sticking EGR valve
• EGR gas leakage from any of the EGR passages between the exhaust manifold
and intake manifold
• Restricted or collapsed EGR passage between the exhaust manifold and the
EGR valve
• Any type of restriction in the exhaust system
• Restricted air cleaner element, restricted or collapsed air tubing between the air
cleaner and the intake manifold
• Any air induction leak
• Any water intrusion in the induction system
• Any contamination or objects that block the MAF sensor inlet
• Skewed or slow MAF sensor
• A ventilation duct that is connected to the exhaust tail pipe. Retest without the duct
if connected.
2. Repair or replace as necessary
Did you find and correct the condition? —
Go to Step 5 Go to Step 4
4 Replace the EGR valve. Refer to EGR Valve
Replacement.
Did you complete the replacement? —
Go to Step 5
—
51. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine and warm up as necessary (allow engine coolant temperature to reach at
least 60 °C [140 °F]).
5. Perform the EGR Solenoid Control with a scan tool.
6. Command the Desired EGR Position Increase or Decrease while observing the MAF Sensor
parameter with a scan tool.
Does the MAF parameter decrease by at least 0.5
volts when the Desired EGR Position is
commanded from 0 to 90%? —
Go to Step 6 Go to Step 3
6 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-163
DTC P0403 (Flash Code 37)
Circuit Description
The ECM controls the EGR valve opening based on the
engine running condition and by controlling the EGR
solenoid. The EGR valve position is detected by the
position sensor, and relayed to the ECM. If the ECM
detects an open circuit or short circuit on the solenoid
circuits, this DTC will set.
Condition for Running the DTC • The battery voltage is more than 9 volts.
• The ignition switch is ON.
Condition for Setting the DTC
Either of following condition is met: • The ECM detects an open circuit on the EGR solenoid circuits.
• The ECM detects a short to ground on the EGR solenoid circuits.
• The ECM detects a short to voltage circuit on the EGR solenoid circuits. Action Taken When the DTC Sets
• The ECM illuminates the MIL on the second consecutive driving cycle when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type B. (Euro 4
Specification)
• The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)
• The ECM inhibits EGR control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type B (Euro 4
Specification)
• Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0403
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC with a scan tool.
Does the DTC fail this ignition? —
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition.
2. Disconnect the EGR valve harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the drive voltage circuit (pin 4 of E-71) and a known good
ground.
5. Connect a DMM between the low side circuit (pin 6 of E-71) and a known good ground.
Are both voltage readings within the specified
value? 1.4 - 1.8 volts
Go to Step 5 Go to Step 4
4 Is the DMM voltage more than the specified value
at Step 3? —
Go to Step 7 Go to Step 6

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ISUZU KB P190 2007

6E-164 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
51. Test the circuits between the ECM (pins 62
and 63 of E-90) and the EGR valve (pins 4
and 6 of E-71) for a short circuit each other.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 12 Go to Step 8
6 1. Test the circuits (which ever voltage reading
did not read within the specified value at Step
3) between the ECM (pins 62 and 63 of E-90)
and the EGR valve (pins 4 and 6 of E-71) for
the following conditions:
• An open circuit
• A short to ground
• A short to the position sensor low reference circuit
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 12 Go to Step 9
7 1. Test the circuits (which ever voltage reading
did not read within the specified value at Step
3) between the ECM (pins 62 and 63 of E-90)
and the EGR valve (pins 4 and 6 of E-71) for a
short to battery or ignition voltage.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 12 Go to Step 11
8 1. Inspect for an intermittent and for poor
connections at the harness connector of the
EGR valve (pins 4 and 6 of E-71).
2. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 12 Go to Step 10
9 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor connections at the harness connector of the
ECM (pins 62 and 63 of E-90).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 12 Go to Step 9
10 Replace the EGR valve. Refer to EGR Valve
Replacement.
Did you complete the replacement? —
Go to Step 10
—
11Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 12
—
Step Action Value(s)Yes No

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-165
121. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 3 Go to Step 13
13 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step Action Value(s) Yes No

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ISUZU KB P190 2007

6E-166 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
DTC P0404 (Flash Code 45)
Circuit Description
The ECM controls the EGR valve opening based on the
engine running condition and by controlling the EGR
solenoid. The EGR valve position is detected by the
position sensor, and relayed to the ECM. If the ECM
detects a variance between the actual EGR valve
position and desired EGR valve position for a
calibrated amount of time while the EGR valve is
commanded ON, this DTC will set.
Condition for Running the DTC • DTCs P0112, P0113, P0116, P0117, P0118, P0405, P0406, P0652, P0653, P2227, P2228 and
P2229 are not set.
• The battery voltage is between 10 to 16 volts.
• The ignition switch is ON.
• The engine coolant temperature is between 20 to 11 0 °C (68 to 230 °F).
• The intake air temperature is between 0 to 110 °C
(32 to 230 °F).
• The barometric pressure is between 60 to 120 kPa (8.7 to 17.4 psi).
• The EGR control is commanded ON. Condition for Setting the DTC
• The ECM detects that the actual EGR position is more than 10% below the desired position for 4
seconds.
Action Taken When the DTC Sets • The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM limits fuel injection quantity.
• The ECM inhibits pilot injection.
• The ECM inhibits EGR control.
• The ECM inhibits cruise control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• A sticking or intermittently sticking EGR valve may set this DTC.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0404
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with a scan tool.
Is DTC P0403, P0405 or P0406 also set? —
Go to Applicable DTC Go to Step 3
3 1. Perform the EGR Solenoid Control with a scan
tool several times.
2. Command the Desired EGR Position Increase and Decrease while observing the EGR
Position.
Does the EGR Position parameter follow within the
specified value quick enough (compare with a
similar unit if available)?
± 5%
Go to Diagnostic Aids Go to Step 4

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-167
41. Remove the EGR valve assembly from the
engine.
2. Inspect the EGR valve for the following conditions:
• Restricted EGR valve by foreign materials
• Excessive deposits at valve
• Bent valve shaft
3. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 5
5 1. Turn OFF the ignition.
2. Disconnect the EGR valve harness connector.
3. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the EGR valve (pins 1, 2, 3, 4
and 6 of E-71).
4. Disconnect the ECM harness connector.
5. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the ECM (pins 30, 31, 32, 62 and
63 of E-90).
6. Test for high resistance on each circuit.
7. Repair the connection(s) or circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 6
6 Replace the EGR valve. Refer to EGR Valve
Replacement.
Did you complete the replacement? —
Go to Step 7
—
71. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007

6E-168 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
DTC P0405 or P0406 (Flash Code 44)
Circuit Description
The exhaust gas recirculation (EGR) position sensor is
installed on the EGR valve body together with the
control solenoid. The EGR position sensor changes
output voltage according to EGR valve position. The
sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• EGR position sensor signal circuit
The EGR position sensor provides a signal to the ECM
on the signal circuit, which is relative to the position
changes of the EGR valve. If the ECM detects an
excessively low or high signal voltage, DTC P0405 or
P0406 will set.
Condition for Running the DTC • DTCs P0652 and P0653 are not set.
• The battery voltage is more than 9 volts.
• The ignition switch is ON.
Condition for Setting the DTC • The ECM detects that the EGR position sensor signal voltage is less than 0.2 volts for 3 seconds.
(DTC P0405)
• The ECM detects that the EGR position sensor signal voltage is more than 4.6 volts for 3 seconds.
(DTC P0406) Action Taken When the DTC Sets
• The ECM illuminates the MIL on the second consecutive driving cycle when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type B. (Euro 4
Specification)
• The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)
• The ECM inhibits EGR control.
• The ECM inhibits cruise control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type B. (Euro 4
Specification)
• Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0405
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with a scan tool.
Is DTC P0652 also set? —
Go to DTC P0652 Go to Step 3
3 Observe the EGR Position Sensor parameter with
a scan tool.
Is EGR Position Sensor parameter less than the
specified value? 0.2 volts
Go to Step 4 Go to Diagnostic
Aids
4 1. Turn OFF the ignition.
2. Disconnect the EGR valve harness connector.
3. Connect a DMM between the 5 volts reference circuit (pin 1 of E-71) and a known good
ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value? 4.7 volts
Go to Step 5 Go to Step 6

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ISUZU KB P190 2007