Isuzu KB P190. Manual - part 288

6E-118 Engine Control System (4JH1)

DTC P0243 (Symptom Code 6) (Flash Code 64)

Circuit Description
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharger
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. When the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure.
The mass air flow (MAF) sensor monitors boost
pressure by monitoring the amount of mass air flow. An
expected MAF amount should be detected while the
engine running. If the ECM detects the actual MAF
amount is higher than desired MAF amount, this DTC
will set. This indicates excessive high boost pressure
and turbocharger wastegate valve most likely did not
active.
Condition for Running the DTC

• The ignition switch is ON.
• The engine coolant temperature (ECT) is between

-50°C (-58 °F) and 150°C (302°F).

•  The EGR solenoid valve control is OFF.
•  The MAF sensor DTC P0100 is not set.
•  The vacuum pressure sensor DTC P0105 is not

set.

• The intake air temperature (IAT) sensor DTC

P0110 is not set.

Condition for Setting the DTC

• The ECM detects that the MAF amount is 56

mg/strk higher than the desired MAF for 3
seconds. This indicates an excessive high boost
pressure.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits fuel injection quantity.
• The ECM uses an EGR solenoid valve control

substitution of 10%.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the scan tool.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Check the wastegate for a sticking or stuck

condition. Refer to Wastegate Operation in the
Engine Mechanical section.

• Use the scan tool to verify the integrity of the MAF

sensor signal. Compare the sensor values under
all load conditions for an excessively high value.
Use the scan tool data list values for nominal
sensor readings.

• The fuel with which gasoline was mixed may set

this DTC.

• A sticking or intermittently sticking the EGR valve

may set this DTC.

• Misrouted vacuum hoses may set this DTC.

DTC P0243 (Symptom Code 6) (Flash Code 64)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action

Value(s)

Yes

Did you perform the Diagnostic System Check-
Engine Controls?



Go to Step 2

Go to Diagnostic

System Check-

Engine Controls

1.  Install the scan tool.
2.  Turn OFF the ignition for 30 seconds.
3.  Start the engine and let idle for 30 seconds.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Is DTC P0105 (Symptom Code 1, 2, 7 or 9), P0243
(Symptom Code 3, 4, 5 or 8) or P0400 (Symptom
Code 3, 4, 5 or 8) set?



Go to Applicable

DTC

Go to Step 3

Engine Control System (4JH1) 6E-119

Step Action

Value(s)

Yes

1. Inspect the following for possible causes of high

boost pressure.

• Wastegate valve for a stuck closed

condition. Refer to the Turbocharger in
Engine Mechanical section for diagnosis.

• Restricted intake or collapsed hose.

2. Repair the condition as necessary.
Did you find and correction the condition?



Go to Step 11

Go to Step 4

1. Turn OFF the ignition for 30 seconds.
2. Start the engine and warm up (allow engine

coolant temperature to reach at least 60°C
[140°F]).

3. Perform the EGR Solenoid Valve test with the

scan tool.

4. Command the EGR Solenoid Valve ON and OFF

with the scan tool while observing the Mass Air
Flow (MAF) Sensor parameter.

Does the MAF Sensor parameter decrease by at
least 200 mg/strk within 2 seconds when the EGR
Solenoid Valve is commanded ON?



Go to Diagnostic

Aids

Go to Step 5

1. Turn OFF the ignition.
2. Inspect for the following conditions:

• An EGR valve control vacuum hose is

damaged or kinked.

• EGR solenoid valve vacuum hoses are

damaged or kinked.

•  EGR solenoid valve ventilation is damaged.
•  An EGR valve is stuck close.
•  Restricted or collapsed EGR passage

between the exhaust manifold and EGR
valve.

• Oil in the air tubing causing an incorrect

MAF sensor signal. When there is
adhesion of oil, inside of the tubing,
intercooler and turbocharger needs to be
wipe off.

• Contaminated or skewed MAF sensor.

3. Repair or replace as necessary.
Did you find and correct the condition?



Go to Step 11

Go to Step 6

1. Turn OFF the ignition.
2. Disconnect the EGR valve control vacuum hose

from the EGR valve.

3. Connect a hand-held vacuum pump (5-8840-

0279-0/J-23738-A) to the disconnected vacuum
hose.

4. Start the engine and let engine idle.
5. Perform the EGR Solenoid Valve test with the

scan tool.

6. Command the EGR Solenoid Valve ON and OFF

with the scan tool.

Does the hand-held vacuum pump indicate more
than 50 cmHg (20 inHg) when commanding the ON
and less than 10 cmHg (4 inHg) when commanding
OFF?



Go to Step 7

Go to Step 10

6E-120 Engine Control System (4JH1)

Step Action

Value(s)

Yes

1. Turn OFF the ignition.
2. Disconnect the hand-held vacuum pump from the

vacuum hose.

3. Connect the hand-held vacuum pump to the

vacuum port of EGR valve.

4. Start the engine and let engine idle.
5. Apply vacuum pressure to the EGR valve while

observing the MAF sensor parameter.

Does the MAF Sensor parameter decrease by at
least 200 mg/strk when the vacuum pressure is
applied?



Go to Diagnostic

Aids

Go to Step 8

1.  Turn OFF the ignition.
2.  Disconnect the MAF sensor harness connector.
3.  Inspect for an intermittent, for a poor connection

and corrosion at the harness connector of the
MAF sensor (pin 3 of C-116 connector).

4. Disconnect the engine control module (ECM)

harness connector.

5. Inspect for an intermittent, for a poor connection

and corrosion on each MAF sensor circuit at the
harness connector of the ECM (pin 92 of C-57
connector).

6. Test for high resistance on each MAF sensor

circuit.

7. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 11

Go to Step 9

Replace the EGR valve. Refer to EGR Valve
Replacement in engine mechanical section.
Did you complete the replacement?



Go to Step 11



Replace the EGR solenoid valve. Refer to EGR
Solenoid Valve Replacement in this section.
Did you complete the replacement?



Go to Step 11



1. Reconnect all previously disconnected harness

connector(s).

2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine and warm up (allow engine

coolant temperature to reach at least 60°C
[140°F]) while observing the MAF Sensor
parameter with the scan tool.

Does the MAF Sensor parameter follow the Desired
MAF parameter within 50 mg/strk?



Go to Step 12

Go to Step 2

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

Engine Control System (4JH1) 6E-121

DTC P0243 (Symptom Code 8) (Flash Code 64)

Circuit Description
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharger
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. When the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure. If the
ECM detects that a short to battery or ignition voltage
on the turbocharger solenoid valve control circuit, this
DTC will set.
Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the high voltage condition

on the turbocharger solenoid valve control circuit
for longer than 3 seconds when the solenoid valve
is commanded ON.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits fuel injection quantity.
• The ECM uses a turbocharger solenoid valve

control substitution of 32%.

• The ECM uses an EGR solenoid valve control

substitution of 10%.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the scan tool.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Test Description
The number below refers to the step number on the
diagnostic table.
3. If the control circuit of the turbocharger solenoid valve
between the ECM and the solenoid valve is normal, the
control circuit voltage low DTC P0243 (Symptom Code
4) will set.

DTC P0243 (Symptom Code 8) (Flash Code 64)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action

Value(s)

Yes

Did you perform the Diagnostic System Check-
Engine Controls?



Go to Step 2

Go to Diagnostic

System Check-

Engine Controls

1.  Install the scan tool.
2.  Turn OFF the ignition for 30 seconds.
3.  Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Does the DTC fail this ignition?



Go to Step 3

Go to Diagnostic

Aids

1. Turn OFF the ignition.
2. Disconnect the turbocharger solenoid valve

harness connector.

3. Start the engine.
4. Monitor the DTC Information with the scan tool.
Does the DTC P0243 (Symptom Code 4) set, but not
DTC P0243 (Symptom Code 8)?



Go to Step 5

Go to Step 4

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