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Isuzu KB P190. Manual - part 867

Engine Management – V6 – Diagnostics

Page 6C1-2–190

Start the engine.

N O T E

Additional DTCs will set when the MAF
sensor is disconnected.

Disconnect the mass air flow (MAF) sensor
harness connector while the engine is operating.

Observe the Short Term FT parameter for Bank 1
and bank 2 with Tech 2.

Reconnect the MAF sensor after completing this
step.

Does the Short Term FT parameter for both banks of
the engine change more than the specified value with
the MAF sensor disconnected?

20%

Go to 7.6

DTC

P0101, P0102 or

P0103 in this

Section

Go to Step 6

Inspect for the following conditions:

−

A collapsed air intake duct

−

A restricted air filter element

−

The MAF sensor for foreign objects

−

Excessive fuel in the crankcase – Change
the oil as necessary.

−

Contaminated fuel. Refer to 6.5 Alcohol /
Contaminants in Fuel Diagnosis in this
Section.

−

The ECM grounds for being clean, tight,
and in the correct locations

−

An engine mechanical condition – refer to
6A1 – Engine Mechanical V6.

Did you find and correct the condition?

—

Go to Step 8

Go to 6C Fuel

System – V6

Inspect for the following conditions:

−

Rich injectors – refer to 6.2

Fuel

Injector Coil Test in this Section

−

Restricted exhaust system – refer to 6F
Exhaust System – V6

−

An engine mechanical condition – refer to
6A1 – Engine Mechanical V6.

Did you find and correct the condition?

—

Go to Step 8

Go to Additional

Information in this

Section.

Switch off the ignition for 30 seconds.

Using Tech 2, clear the DTCs and reset the fuel
trim system.

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 DTC P2178 and / or P2180 fail this ignition cycle?

—

Go to Step 2

Go to Step 9

Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

—

Go to the

appropriate DTC

Table in this

Section System

Engine Management – V6 – Diagnostics

Page 6C1-2–191

7.53 DTC P2187 or P2189

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P2187 Fuel Trim System Lean at Idle Bank 1

•

DTC P2189 Fuel Trim System Lean at Idle Bank 2

Circuit Description

The engine control module (ECM) controls the air / fuel metering system to provide the best possible combination of
driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open and Closed Loop.
During Open Loop, the ECM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S)
input. During Closed Loop, the HO2S inputs are added and used by the ECM to calculate short and long term fuel trim
fuel delivery adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0 percent. If the O2S
indicate a rich condition, fuel trim values will be below 0 percent. Short term fuel trim values change rapidly in response
to the HO2S signals. Long term fuel trim makes coarse adjustments to maintain an air / fuel ratio of 14.7:1. If the ECM
detects an excessively lean condition, this DTC sets.

Conditions for Running the DTC

•

Before the ECM can report DTC P2187 or P2189 failed, DTCs P0101, P0121, P0122, P0123, P0133, P0153,
P0221, P0222, P0223, P0336, P0338, P0443, P0458, P0459, P0461, P0462, P0463, P2066, P2067, and P2068
must run and pass.

•

The fuel system is in closed loop.

•

The long fuel trim is active.

•

The engine coolant temperature (ECT) is more than 60° C.

•

The evaporative emission (EVAP) canister purge solenoid valve is not enabled.

•

The intake air temperature (IAT) is less than 60° C.

•

The fuel level is more than 11.6 percent.

•

The amount of air flow into the engine is more than 7000 grams.

•

DTC P2187 and P2189 runs continuously once the above conditions are met for at least 300 seconds.

Conditions for Setting the DTC

•

The Total Fuel Trim Avg. is more than 40 percent.

•

The LT FT Idle / Decel is more than seven percent.

•

The condition exists for four seconds.

Action Taken When the DTC Sets

The control module 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 Fuel Trim System circuit DTCs are Type ‘B’ DTCs. Refer to 1.4

Diagnostic Trouble Codes in this Section,

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

•

Use Tech 2 to clear the MIL and the DTC.

Engine Management – V6 – Diagnostics

Page 6C1-2–192

Additional Information

•

A fuel delivery condition causes this DTC to set. Thoroughly inspect all items that could cause a rich condition.

•

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.

Test Description

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

This step determines if there is a current condition.

If DTC P2187 and P2189 are set at the same time, this indicates that both banks of the engine are operating lean.
Inspect for items that would cause both banks of the engine to operate lean.

Disconnecting the mass air flow (MAF) sensor determines if the MAF sensor signal is skewed. If the Short Term
FT parameter changes more than the specified value, there is a condition with the MAF sensor. A MAF sensor
condition can cause this DTC without setting a MAF DTC. If there is a MAF sensor condition, the MAF sensor
parameters will appear to be within range.

A vacuum leak causes DTC P2187 and P2189 to set at the same time. Inspect all areas of the engine for a
vacuum leak. Also inspect the positive crankcase ventilation (PCV) valve for being the correct one for this
application. Make sure that the engine oil fill cap is in place and that it is tight. Verify that the engine oil dip stick is
fully seated.

DTC P2187 or P2189 Diagnostic Table

Step Action Value(s)

Yes

Has the Diagnostic System Check been completed?

—

Go to Step 2

Refer to

4.4 Diagnostic

System Check in this

Section

N O T E

If any DTCs are set, except P2187 and
DTC P2189, refer to those DTCs before
proceeding with this diagnostic.

Idle the engine at the normal operating
temperature.

The fuel system is in Closed Loop.

Observe the Total Fuel Trim Avg. parameter for
bank 1 and / or bank 2 with a scan tool.

Is the Total Fuel Trim Avg. less than the specified
value?

40%

Go to Step 3

Go to Step 4

Observe the Freeze Frame and / or the Failure
records data for this DTC.

Turn the ignition OFF for 30 seconds.

Start the engine.

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 and / or the Failure
records data.

Does the DTC fail this ignition cycle?

—

Go to Step 4

Refer to Additional

Information in this

DTC.

Are both banks of the engine operating lean?

—

Go to Step 5

Go to Step 7

Engine Management – V6 – Diagnostics

Page 6C1-2–193

Start the engine.

N O T E

Additional DTCs will set when the MAF
sensor is disconnected.

Disconnect the mass air flow (MAF) sensor
harness connector while the engine is operating.

Observe the Short Term FT parameter for bank 1
and bank 2 with Tech 2.

Reconnect the MAF sensor after completing this
step.

Does the Short Term FT parameter for both banks of
the engine change more than the specified value with
the MAF sensor disconnected?

20%

Go to 7.6

DTC

P0101, P0102 or

P0103 in this

Section

Go to Step 6

Inspect for the following conditions:

−

Vacuum hoses for splits, kinks, and proper
connections.

−

The throttle body and the intake manifold
for vacuum leaks.

−

The crankcase ventilation valve and system
for leaks.

−

Air intake system after the MAF sensor for
vacuum leaks.

−

Contaminated fuel – Refer to 6.5 Alcohol /
Contaminants in Fuel Diagnosis in this
Section.

−

Lean injectors – Refer to 6.2

Fuel

Injector Coil Test in this Section.

−

The ECM grounds for being clean, tight,
and in the correct locations

−

A high engine oil level condition. A high
engine oil level causes oil residue to form
on the MAF sensor, causing a lean
indication. The MAF sensor does not need
to be replaced.

−

An engine mechanical condition – refer to
6A1 – Engine Mechanical V6.

Did you find and correct the condition?

—

Go to Step 8

Refer to Additional

Information and Test

Descriptionin this

DTC

Inspect for the following conditions:

−

Vacuum leaks that only affect one bank of
the engine – For example, the intake
manifold, the injector O-rings.

−

Lean injectors – refer to 6.2

Fuel

Injector Coil Test in this Section

−

Exhaust leaks, missing or loose exhaust
hardware.

−

The heated oxygen sensor (HO2S) is
installed securely and the electrical
connector is not contacting the exhaust
system.

−

An engine mechanical condition – 6A1 –
Engine Mechanical V6.

Did you find and correct the condition?

—

Go to Step 8

Refer to Additional

Information in this

DTC.

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