Isuzu KB P190. Manual — part 841

Engine Management – V6 – Diagnostics

Page 6C1-2–86

DTC P2243 and P2247

The ECM detects the internal HO2S signal voltage is not 0.2 – 4.7 V.

DTC P2270 and P2272

When the ECM detects the HO2S 2 is less than 650 mV for 100 seconds, the ECM enriches the fuel mixture up to 30
percent for 10 seconds. This DTC sets if the ECM detects the HO2S 2 is still less than 650 mV.

DTC P2271 and P2273

When the ECM detects the HO2S 2 is greater than 650 mV for 100 seconds, the ECM leans the fuel mixture up to -7
percent for 10 seconds. If this signal voltage is still greater than 650 mV, the ECM tests the HO2S at the next decel fuel
cut-off. This DTC sets if the ECM detects the HO2S 2 signal voltage is greater than 200 mV after 4 seconds in decel fuel
cu-off mode.

DTC P2297 and P2298

The ECM detects the internal HO2S 1 signal voltage is greater than 3.7 V for longer than 10 seconds.

Conditions for Clearing the DTC

The HO2S reference 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.

•

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

•

A fault condition in the fuel delivery system, air intake system or exhaust system may 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 P0130 to P0132, P0135 to P0138, P0140, P0141, P0150 to P0152, P0155, P0157, P0158,
P0160, P0161, P2243, P2247, P2270 to P2273, P2297 or P2298 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 or
operate the vehicle within the conditions for setting the DTC.

5

Using Tech 2, select the DTC display function.

Does DTC P0130, P0131, P0132, P0135, P0137, P0138, P0140,
P0141, P0150, P0151, P0152, P0155, P0160, P0161, P2243, P2247,
P2270, P2271, P2272, P2273, P2297 or P2298 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

Are DTCs relating to the heater circuit of the O2 sensor, also set?
(e.g. P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051,
P0052, P0056, P0057 or P0058)

Go to the

appropriate DTC

Table in this Section

Go to Step 4

Engine Management – V6 – Diagnostics

Page 6C1-2–87

Step Action

Yes

No

4

1

Disconnect the appropriate HO2S wiring connector.

2

Switch on the ignition with the engine not running.

3

Using a digital multimeter, measure the voltage between the
HO2S reference signal circuit and low reference circuit.

Does the multimeter display 350 – 550 mV?

Go to Step 7

Go to Step 5

5

1

Test the reference signal circuit of the HO2S 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 10

Go to Step 6

6

1

Test the low reference circuit of the HO2S 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 10

Go to Step 9

7

1

Test or inspect for the following conditions that may cause the
HO2S to detect an incorrect air / fuel mixture:

−

lean or rich fuel injector fuel delivery,

−

restricted air intake system,

−

contaminated fuel,

−

low fuel line pressure,

−

exhaust leak near the HO2S, and

−

leak in the crankcase or vacuum line.

Was any fault found and rectified?

Go to Step 10

Go to Step 8

8

1

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

Was the repair completed?

Go to Step 10

—

9

1

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

Was the repair completed?

Go to Step 10

—

10 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 HO2S reference circuit DTC fail this ignition cycle?

Go to Step 2

Go to Step 11

11 1

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.

7.11 DTC P0133 or P0153

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0133 – HO2S Circuit Slow Response – Bank 1 Sensor 1

Engine Management – V6 – Diagnostics

Page 6C1-2–88

•

DTC P0153 – HO2S Circuit Slow Response – Bank 2 Sensor 1

Circuit Description

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides
more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen
pumping cell, and a heater.

The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine
control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in
the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell to
maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and
attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the
pumping cell.

By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the
concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal
to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1.
When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the
fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this
information to maintain the correct air / fuel ratio.

Conditions for Running the DTC

•

Before the ECM can report DTC P0133 or P0153 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223,
P0336, P0338, P2237, and P2240 must run and pass.

•

DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0053, P0059, P0130, P0131, P0132, P0135, P0150, P0151,
P0151, P0152, P0155, P0442, P0443, P0446, P0455, P0458, P0459, P0496, P167A, P167B, P2096, P2097,
P2098, P2099, P2231, P2234, P2243, P2247, P2251, P2254, P2297, P2298, P2626, and P2629 are not set.

•

The HO2S is at operating temperature.

•

The HO2S is between 0.94 – 1.06 lambda.

•

The engine speed is between 1,480 – 2,040 rpm.

•

The volumetric efficiency is between 16.5 – 38.3 percent.

•

The change in volumetric efficiency is less than 3 percent.

•

The evaporative emission (EVAP) purge is not active, or the ECM determines the EVAP hydrocarbon (HC)
concentration is less than a predetermined amount when EVAP purge is active.

•

The long term fuel trim correction is active.

•

DTCs P0133 and P0153 run continuously once the above conditions are met for 10 minutes.

Conditions for Setting the DTC

•

The ECM has determined that the dynamic value of the affected HO2S is less than a predetermined threshold.

•

The above condition is met for more than 4 seconds.

Action Taken When the DTC Sets

•

The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the
diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic
fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the
second consecutive ignition cycle, the control module records the operating conditions at the time of the failure.
The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•

The ECM turns OFF the malfunction indicator lamp (MIL) after four consecutive ignition cycles that the diagnostic
runs and does not fail.

•

A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

Engine Management – V6 – Diagnostics

Page 6C1-2–89

•

A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.

•

Use Tech 2 to clear the MIL/DTC.

Additional Information

•

Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a
component harness connector.

•

The lower connector of the ECM is connector A43-X1 and the upper connector of the ECM is connector A43-X2.
Refer to 3 Wiring Diagrams and Connector Charts in this Section.

•

The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be
relatively stable for an idling engine.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

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.

•

The following table illustrates the typical voltages for the HO2S circuits:

HO2S Voltages

Conditions:

•

Ignition ON, Engine OFF

•

HO2S Disconnected

HO2S Circuit

Voltage

Heater Control

4.6 – 5.0 V

Heater Supply Voltage

B+

Reference Voltage

2.6 – 3.1 V

Low Reference

2.2 – 2.7 V

Pump Current

Less than 0.5 A

Input Pump Current

Less than 0.5 A

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2

This step determines if the condition exists.

4

This step determines if the fuel system is contaminated.

DTC P0133 or P0153 Diagnostic Table

Step Action

Yes

No

1

Has the Diagnostic System Check been completed?

Go to Step 2

Refer to

4.4 Diagnostic

System Check