Isuzu KB P190. Manual — part 836

Engine Management – V6 – Diagnostics

Page 6C1-2–66

•

The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs.

•

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.

Conditions for Running the DTC

Run continuously once the following conditions are met:

•

The ignition voltage is 10.0 – 16.0 V.

•

The engine is running.

•

The O2 Sensors are in closed loop.

•

The ECM is commanding the HO2Ss fuel trim.

Conditions for Setting the DTC

The ECM detects the HO2S signal voltages are heading in the opposite direction of what was commanded.

Conditions for Clearing the DTC

The HO2S signal not plausible 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.

DTC P0040 and P0041 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 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 P0040 or P0041 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

Check the HO2S 2 wiring connectors for a swapped connector fault
condition.

Was any fault found and rectified?

Go to Step 5

Go to Step 4

4

Are DTCs relating to other circuits of the HO2S also set?

Go to the

appropriate DTC in

this Section

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 HO2S signal not plausible or wire connector swapped
DTCs fail this ignition cycle?

Go to Step 2

Go to Step 6

Engine Management – V6 – Diagnostics

Page 6C1-2–67

Step Action

Yes

No

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.

7.5

DTC P0053 or P0059

DTC Descriptor

This diagnostic procedure supports the following DTCs:

•

DTC P0053 – O2 Sensor Heater Resistance Range / Performance (Bank 1, Sensor 1)

•

DTC P0059 – O2 Sensor Heater Resistance Range / Performance (Bank 2, Sensor 1)

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 maintains the voltage between the reference signal circuit and low reference circuit of the HO2S 1 to about
450 mV by increasing or decreasing the oxygen content in the HO2S diffusion gap. To achieve this, the ECM controls
the current applied to the oxygen pumping cell in the HO2S.

•

If the air / fuel mixture in the exhaust is balanced (lambda = 1), the oxygen pumping cell current is zero.

•

If the exhaust gas in the HO2S 1 diffusion gap is lean, the ECM applies a positive current to the oxygen pumping
cell to discharge oxygen from the diffusion gap.

•

If the exhaust gas in the HO2S 1 diffusion gap is rich, the ECM applies a negative current to the oxygen pumping
cell to draw oxygen into the diffusion gap.

The pumping current required to maintain the HO2S 1 signal circuit voltage to about 450 mV is proportional to the level
of oxygen concentration in the exhaust gas. The ECM monitors and evaluates the oxygen pumping current to determine
the level of oxygen concentration in the exhaust.

An HO2S internal heater resistance performance DTC sets if the ECM detects an internal fault condition in the ECM
HO2S heater circuit.

Conditions for Running the DTC

Run continuously once the following conditions are met:

•

DTCs P0030, P0031, P0032, P0101, P0121, P012, P0123, P0131, P0132, P0133, P0221, P0222, P0223, P0336,
P0338, P2237, P2243 and P2626 ran and passed.

•

The calculated exhaust temperature is greater than 400ºC.

•

The engine does not misfire.

•

The ignition voltage is 10.0 – 16.0 V.

•

The HO2S is commanded on.

•

The engine is running at speed greater than 25 rpm

Conditions for Setting the DTC

There is an internal fault condition in the ECM HO2S heater circuit.

Conditions for Clearing the DTC

The HO2S internal heater resistance performance 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.

Engine Management – V6 – Diagnostics

Page 6C1-2–68

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.

•

The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs.

•

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.

DTC P0053 and P0059 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 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 P0053 or P0059 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

Are DTCs relating to other circuits of the HO2S also set?

Go to the

appropriate DTC

Table in this Section

Go to Step 4

4

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

Was the repair completed?

Go to Step 5

—

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 HO2S internal heater resistance performance 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.

7.6

DTC P0101, P0102 or P0103

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0101 – Mass Air Flow Sensor Circuit Range / Performance

•

DTC P0102 – Mass Air Flow Sensor Voltage Low

•

DTC P0103 – Mass Air Flow Sensor Voltage High

Engine Management – V6 – Diagnostics

Page 6C1-2–69

Circuit Description

The ignition control relay applies ignition positive voltage to the mass airflow (MAF) sensor. The ECM applies 5 V
reference voltage and ground through the low reference circuit.

A heater resistor on the MAF sensor heats a micro-mechanical sensor diaphragm at a constant temperature. Two
temperature dependent resistors positioned at each side of the heater resistor measure the intake air temperature:

•

The first is located at a position before the intake air passes through the heater resistor. This temperature
dependent resistor measures the temperature of the intake air before the air is heated.

•

The second is located at a position after the intake air has passed through the heater resistor. This sensor
measures the temperature of the intake air after the air is heated.

The evaluation circuit on the MAF sensor converts the difference in the resistance value of these two temperature
dependent resistors into an analogue signal voltage. The ECM monitors this signal voltage through the MAF sensor
signal to calculate the engine intake air mass.

A MAF sensor circuit DTC sets if the ECM detects the actual MAF sensor signal is not within the predetermined range of
the calculated MAF sensor value.

Conditions for Running the DTC

DTC P0101

Runs continuously once the following conditions are met:

•

DTCs P0121, P0122, P0123, P0221, P0222 and P0223 ran and passed.

•

The engine is running.

•

The ignition voltage is 10.0 – 16.0 V.

•

The MAF sensor signal is -11.6 to +295 grams per second.

•

The ECM detects greater than 150 crankshaft revolutions.

DTC P0102

Runs continuously once the following conditions are met:

•

DTCs P0121, P0122, P0123, P0221, P0222 and P0223 ran and passed.

•

The engine is running.

•

The ignition voltage is 10.0 – 16.0 V.

DTC P0103

Runs continuously once the following conditions are met:

•

DTCs P0121, P0122, P0123, P0221, P0222 and P0223 ran and passed.

•

The engine is running at speed greater than 320 rpm

•

The ignition voltage is 10.0 – 16.0 V.

Conditions for Setting the DTC

DTC P0101

The ECM detects the MAF sensor signal is not within the predetermined range of the calculated MAF value for 2
seconds.

DTC P0102

The ECM detects the MAF sensor signal is less than -11.7 grams per second.

DTC P0103

The ECM detects the MAF sensor signal is greater than 294 grams per second.