Isuzu KB P190. Manual — part 835

Engine Management – V6 – Diagnostics

Page 6C1-2–62

DTC P0008, P0009 or P0016 Diagnostic Table

Step Action

Yes

No

1

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.4 Diagnostic
System Check in

this Section

2

1

Switch off the ignition for 30 seconds.

2

Start the engine.

3

Allow the engine to reach the normal operating temperature.

4

Increase the engine speed to 2,000 rpm for 10 seconds.

5

Using Tech 2, select the DTC display function.

Does DTC P0008, P0009 or P0016 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

1

Are DTCs relating to the following DTCs also set:

•

Camshaft actuator circuit

•

CMP sensor circuit

•

CKP sensor circuit

Go to the

appropriate DTC

Table in this Section

Go to Step 4

4

1

Inspect the engine for the following fault conditions. Refer to
6A1 Engine Mechanical – V6:

•

incorrect installation of the CMP sensor,

•

incorrect installation of the CKP sensor,

•

timing chain tensioner fault condition,

•

incorrectly installed timing chain,

•

excessive play in the timing chain, and

•

timing chain that jumped teeth.

Was any fault found and rectified?

Go to Step 5

Refer to Additional

Information in this

DTC

5

1

Using Tech 2, clear the DTCs.

2

Switch off the ignition for 30 seconds.

3

Start the engine.

4

Operate the vehicle within the conditions for running the DTC.

Does any of the crankshaft / camshaft position correlation DTCs fail
this ignition cycle?

Go to Step 2

Go to Step 6

6

Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

7.3

DTC P0030, P0031, P0032, P0036, P0037,
P0038, P0050, P0051, P0052, P0056,
P0057 or P0058

DTC Descriptor

This diagnostic procedure supports the following DTCs:

•

DTC P0030 – O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)

•

DTC P0031 – O2 Sensor Heater Circuit Low Voltage (Bank 1, Sensor 1)

Engine Management – V6 – Diagnostics

Page 6C1-2–63

•

DTC P0032 – O2 Sensor Heater Circuit High Voltage (Bank 1, Sensor 1)

•

DTC P0036 – O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)

•

DTC P0037 – O2 Sensor Heater Circuit Low Voltage (Bank 1, Sensor 2)

•

DTC P0038 – O2 Sensor Heater Circuit High Voltage (Bank 1, Sensor 2)

•

DTC P0050 – O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)

•

DTC P0051 – O2 Sensor Heater Circuit Low Voltage (Bank 2, Sensor 1)

•

DTC P0052 – O2 Sensor Heater Circuit High Voltage (Bank 2, Sensor 1)

•

DTC P0056 – O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)

•

DTC P0057 – O2 Sensor Heater Circuit Low Voltage (Bank 2, Sensor 2)

•

DTC P0058 – O2 Sensor Heater Circuit High Voltage (Bank 2, Sensor 2)

Circuit Description

The engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S. The ECM applies a
pulse width modulated (PWM) ground to the heater control circuit of the HO2S through a device within the ECM called a
driver, to control the HO2S rate of heating.

The driver has a feedback circuit that is pulled-up when the voltage is approximately 3.3 V. The ECM monitors the driver
feedback circuit to determine if the control circuit is open, shorted to ground or shorted to a positive voltage.

An HO2S heater control circuit DTC sets if the ECM detects a high resistance, open circuit, short to ground or short to
voltage fault condition in the HO2S heater control circuit.

Conditions for Running the DTC

Runs continuously once the following conditions are met:

•

The ignition voltage is 10.0 – 16.0 V.

•

Engine speed is greater than 80 rpm

Conditions for Setting the DTC

DTC P0030, P0036, P0050 or P0056

The ECM detects an open circuit fault condition in the HO2S heater control circuit when the HO2S heater is commanded
off.

DTC P0031, P0037, P0051 or P0057

The ECM detects a short to ground fault condition in the HO2S heater control circuit when the HO2S heater is
commanded off.

DTC P0032, P0038, P0052 or P0058

The ECM detects a short to voltage fault condition in the HO2S heater control circuit for five seconds when the HO2S
heater is commanded on.

Conditions for Clearing the DTC

The HO2S heater control circuit DTCs are Type B DTCs. Refer to 1.4

Diagnostic Trouble Codes in this Section, for

action taken when Type B DTC sets and conditions for clearing Type B DTCs.

Additional Information

•

Refer to 6C1-1 Engine Management – V6 – General Information for details of the HO2S system operation.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

A faulty HO2S heater element may cause an open heater circuit condition. This fault may be intermittent or only
show up after the sensor has operated for a period.

Engine Management – V6 – Diagnostics

Page 6C1-2–64

•

Inspect the HO2S wiring harness for contact with the exhaust system.

•

The front and the rear HO2Ss have a separate fuse connection. If both front or both the rear DTCs are set, the
appropriate HO2S ignition voltage circuit may be open.

•

Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.

•

To assist diagnosis, refer to 3

Wiring Diagrams and Connector Charts in this Section, for the system wiring

diagram and connector charts.

Test Description

The following number refers to the step number in the diagnostic table:

4

The ECM monitors the driver feedback circuit to determine if the heater control circuit is open, shorted to ground or
shorted to a positive voltage. If the voltage is outside the specified range, there is a fault condition with the heater
control circuit.

DTC P0030 to P0032, P0036 to P0038, P0050 to P0052 and P0056 to P0058 Diagnostic Table

Step Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.4 Diagnostic

System Check in

this Section

2

1

Switch off the ignition for 30 seconds.

2

Start the engine.

3

Allow the engine to run at idle speed for at least 30 seconds.

4

Increase the engine speed to 2,000 rpm for 10 seconds.

5

Using Tech 2, select the DTC display function.

Does DTC P0030, P0031, P0032, P0036, P0037, P0038, P0050,
P0051, P0052, P0056, P0057 or P0058 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

1

Disconnect the appropriate HO2S wiring connector.

2

Switch on the ignition with the engine not running.

3

Connect a test lamp between the HO2S heater ignition voltage
circuit and the ECM housing.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

Using a digital multimeter, measure the voltage between the HO2S
heater control circuit and a good ground.

Does the multimeter display:

•

HO2S 1: 4.6 – 5.2 V?

•

HO2S 2: 2.8 – 4.2 V?

Go to Step 7

Go to Step 6

5

N O T E

The HO2S ignition voltage circuit is shared with other
sensors. Ensure that all circuits and components that
share this ignition voltage circuit are tested for a short to
ground.

Repair the high resistance open circuit or short to ground fault
condition in the HO2S heater ignition voltage circuit. Refer to 8A
Electrical - Body and Chassis for information on electrical wiring
repair procedures.

Was the repair completed?

Go to Step 9

—

Engine Management – V6 – Diagnostics

Page 6C1-2–65

Step Action

Yes

No

6

Test the HO2S heater control circuit for a high resistance, open
circuit, short to ground or short to voltage fault condition. Refer to 8A
Electrical - Body and Chassis for information on electrical fault
diagnosis.

Was any fault found and rectified?

Go to Step 9

Go to Step 8

7

Replace the appropriate HO2S. Refer to 6C1-3 Engine Management
– V6 – Service Operations.

Was the repair completed?

Go to Step 9

—

8

Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.

Was the repair completed?

Go to Step 9

—

9

1

Using Tech 2, clear the DTCs.

2

Switch off the ignition for 30 seconds.

3

Start the engine.

4

Operate the vehicle within the conditions for running the DTC.

Does any of the HO2S heater control circuit DTCs fail this ignition
cycle?

Go to Step 2

Go to Step 10

10 Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

7.4

DTC P0040 or P0041

DTC Descriptor

This diagnostic procedure supports the following DTCs:

•

DTC P0040 – O2 Sensor Signals Not Plausible (Bank 1, Sensor 1 & Bank 2, Sensor 1)

•

DTC P0041 – O2 Sensor Signals Not Plausible (Bank 1, Sensor 2 & Bank 2, Sensor 2)

Circuit Description

The engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S. The ECM applies a
pulse width modulated (PWM) ground to the heater control circuit of the HO2S through a device within the ECM called a
driver, to control the HO2S rate of heating.

The ECM applies a voltage of approximately 450 mV between the reference signal circuit and low reference circuit of the
HO2S while the sensor temperature is less than the operating range.

Once the HO2S reaches operating temperature, the sensor varies this reference signal voltage, which constantly
fluctuates between the high voltage output and the low voltage output.

•

The low voltage output is 0 – 450 mV, which occurs if the air fuel mixture is lean.

•

The high voltage output is 450 – 1,000 mV, which occurs if the air fuel mixture is rich.

The ECM monitors, stores and evaluates the HO2S voltage fluctuation information to determine the level of oxygen
concentration in the exhaust.

An HO2S signal not plausible or wire connector swapped DTC sets if the ECM detects the HO2S signal voltages are
heading in the opposite direction of what was commanded.

Additional Information

•

Refer to 6C1-1 Engine Management – V6 – General Information for details of the HO2S system operation.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.