Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1274

6E1–172

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

D

A history Diagnostic Trouble Code P0138 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

D

Diagnostic Trouble Code P0138 can be cleared by
using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check the following items:

D

Fuel pressure – An excessively rich fuel mixture can
cause a Diagnostic Trouble Code P0138 to be set.
Refer to Fuel System Diagnosis. 

D

Rich injector(s) – Perform ”Injector Balance Test.”

D

Leaking injector – Refer to Fuel System Diagnosis. 

D

Evaporative emissions (EVAP) canister purge – Check
for fuel saturation. If full of fuel, check the canister
control and hoses. Refer to Evaporative Emission
(EVAP) Control System. 

D

Check for a leaking fuel pressure regulator diaphragm
by checking the vacuum line to the regulator for the
presence of fuel.

D

TP sensor – An intermittent TP sensor output will
cause the system to go rich, due to a false indication
of the engine accelerating.

D

Shorted Heated Oxygen Sensor (HO2S) – If the HO2S
is internally shorted the HO2S voltage displayed on the
Tech 2 will be over 1 volt. Silicon contamination of the
HO2S can also cause a high HO2S voltage. This
condition is indicated by a powdery white deposit on
the portion of the HO2S exposed to the exhaust

stream. If contamination is evident, replace the
affected HO2S.

D

Open HO2S Signal, Low Circuit or Faulty HO2S – A
poor connection or open in the HO2S signal or low
circuit can cause the DTC to set during deceleration
fuel mode.  An HO2S which is faulty and not allowing
a full voltage swing between the rich and lean
thresholds can also cause this condition. Operate the
vehicle while monitoring the HO2S voltage with a Tech
2. If the HO2S voltage is limited within a range between
300 mV to 600 mV, check the HO2S signal and low
circuit wiring and associated terminal connections. If
the wiring and connections are OK, replace the HO2S.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
3.Diagnostic Trouble Code P0138 being set during

deceleration fuel mode operation may indicate a
condition described in the ”Diagnostic Aids” above.
If the Diagnostic Trouble Code P0138 test passes
while the Failure Records conditions are being
duplicated, an intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage
since the diagnostic test last failed may help
determine how often the condition that caused the
Diagnostic Trouble Code to be set occurs. This may
assist in diagnosing the condition.

DTC P0138 – O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

 

Step

Action

Value(s)

Yes

No

1

Was the ”On–Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2 

Go to OBD

System

Check 

2

1. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within parameters specified

under ”Conditions for Setting the Diagnostic
Trouble Code” included in Diagnostic Support.

4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Does the Bank 1 HO2S 2 voltage remain above the
specified value?

952 mV

Go to Step 4 

Go to Step 3 

3

1. Ignition ON review and record Tech 2 Failure

Records data.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor “Diagnostic Trouble Code”

info for Diagnostic Trouble Code P0138 until the
Diagnostic Trouble Code P0138 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code
P0138 failed this ignition?

—

Go to Step 4 

Refer to

Diagnostic

Aids 

6E1–173

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTC P0138 – O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

  (Cont'd)

Step

No

Yes

Value(s)

Action

4

1. Ignition OFF.
2. Disconnect Bank 1 HO2S 2.
3. Ignition ON.
4. At HO2S 2 connector (PCM side) use a DVM to

measure voltages at the high and low signal
terminals.

Are the voltages in the specified range?

5–14 V

Go to Step 5 

Go to Step 6 

5

Repair short to voltage in signal circuit.

—

Verify repair

—

6

1. Ignition OFF.
2. Disconnect the PCM connector.
3. Check for damage to the PCM pins and terminals.

Was a problem found?

—

Verify repair

Go to Step 7 

7

1. Ignition ON, engine OFF.
2. Disconnect Bank 1 HO2S 2 and jumper the HO2S

high and low circuits (PCM side) to ground.

3. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.

Is Bank 1 HO2S 2 voltage below the specified value?

10 mV

Go to Step 8 

Go to Step 9 

8

Replace Bank 1 HO2S 2.

Is the action complete?

—

Verify repair

—

9

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed. Refer to On–Vehicle Service in
Powertrain Control Module and Sensors for
procedures. 

And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.

Is the action complete?

—

Verify repair

—

6E1–174

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P0140 O2 SENSOR CIRCUIT NO 

ACTIVITY DETECTED (BANK 1 SENSOR 2)

060R100031

Circuit Description

To control emissions of hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen (NOx), a
three–way catalytic converter is used. The catalyst within
the converter promotes a chemical reaction which
oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx, converting it to
nitrogen. The powertrain control module (PCM) has the
ability to monitor this process using the Bank 1 HO2S 1
and the Bank 1 HO2S 2 heated oxygen sensors. The
Bank 1 HO2S 2 sensor produces an output signal which
indicates the amount of oxygen present in the exhaust
gas entering the three–way catalytic converter. The Bank
1 HO2S 2 sensor produces an output signal which
indicates the oxygen storage capacity of the catalyst; this
in turn indicates the catalyst’s ability to convert exhaust
gases efficiently. If the catalyst is operating efficiently, the
Bank 1 HO2S 1 signal will be far more active than that
produced by the Bank 1 HO2S 2 sensor. If the Bank 1
HO2S 2 signal voltage remains between 400 mV and 500
mV for an extended period of time, Diagnostic Trouble
Code P0140 will be set.  DTC P0140 is a type A code.

Conditions for Setting the DTC

D

No related Diagnostic Trouble Codes.

D

Engine run time is longer than 120 seconds.

D

Oxygen sensor heater is functioning properly, and the
oxygen sensor has reached operating temperature.

D

Engine is operating in ”Closed Loop”.

D

Bank 1 HO2S 2 signal voltage remains between 426
mV and 474 mV.

The above conditions are met for 850 test failures in 1000
test samples (125 msec/test).

Action Taken When the DTC Sets

D

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

D

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

Conditions for Clearing the MIL/DTC

D

The PCM will turn the MIL OFF on the third consecutive
trip cycle during which the diagnostic has been run and
the fault condition is no longer present.

D

A history Diagnostic Trouble Code P0140 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

D

Diagnostic Trouble Code P0140 can be cleared by
using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

D

Poor connection or damaged harness – Inspect the
harness connectors for backed–out terminals,

6E1–175

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

improper mating, broken locks, improperly formed or
damaged terminals, poor terminal–to–wire
connection, shorts to ground, shorts to battery positive
and open circuits.

D

Faulty HO2S heater or heater circuit – With the ignition
ON engine OFF the HO2S voltage displayed on a Tech
2 should gradually drop to below 250 mV. If not,
disconnect the HO2S and connect a test light between
the HO2S ignition feed and heater ground circuits. If
the test light does not light, repair the open ignition feed
or sensor ground circuit as necessary. If the test light
lights and the HO2S signal and low circuits are OK,
replace the HO2S.

D

Intermittent test – With the ignition ON monitor the
HO2S signal voltage while moving the wiring harness
and related connectors. If the fault is induced, the

HO2S signal voltage will change. This may help isolate
the location of the malfunction.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
3.If the Diagnostic Trouble Code P0140 test passes

while the Failure Records conditions are being
duplicated, an intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage
since the diagnostic test last failed may help
determine how often the condition that caused the
Diagnostic Trouble Code to be set occurs. This may
assist in diagnosing the condition.

DTC P0140 – O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

 

Step

Action

Value(s)

Yes

No

1

Was the ”On–Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2 

Go to OBD

System

Check 

2

1. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the engine above 1200 RPM for two

minutes.

Does the Tech 2 indicate Bank 1 HO2S 2 voltage vary
outside the specified value?

425–475 mV

Go to Step 3 

Go to Step 4 

3

1. Ignition ON engine OFF review and record Tech 2

Failure Records data and note parameters.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using a Tech 2, monitor “Diagnostic Trouble Code”

info for Diagnostic Trouble Code P0140 until the
Diagnostic Trouble Code P0140 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code
P0140 failed this ignition?

—

Go to Step 4 

Refer to

Diagnostic

Aids 

4

Check for a poor Bank 1 HO2S 2 high or low signal
circuit terminal connection at the Bank 1 HO2S 2
harness connector and replace terminal(s) if
necessary.

Did any terminals require replacement?

—

Verify repair

Go to Step 5 

5

1. Ignition OFF.
2. Disconnect the PCM.
3. Check for poor Bank 1 HO2S 2 high or low signal

circuit terminal connection at the PCM and replace
the terminal if necessary.

Did either terminal require replacement?

—

Verify repair

Go to Step 6 

6

Check continuity of the Bank 1 HO2S 2 signal circuits.
If either Bank 1 HO2S 2 signal circuit measures over 5

W

, repair open or poor connection as necessary.

Was a Bank 1 HO2S 2 signal circuit problem found and
corrected?

—

Verify repair

Go to Step 7