Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1273

6E1–168

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) 

P0137  O2 SENSOR CIRCUIT LOW VOLTAGE (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 1 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 excessively low for an
extended period of time, Diagnostic Trouble Code P0137
will be set.  DTC P0137 is a type A code.

Conditions for Setting the DTC

D

No related Diagnostic Trouble Codes.

D

Engine is operating in ”Closed Loop”.

D

Engine coolant temperature is above 60

°

C (140

°

F). 

D

”Closed Loop” commanded air/fuel ratio is between
14.5 and 14.8.

D

Throttle angle is between 5.9% and 50%.
All above conditions met for 0.3 seconds or for 3.0
seconds, if in ”Decelleration Fuel Cut–Off” (DFCO)
mode, and the following two conditions are met:

D

Bank 1 HO2S 2 signal voltage remains below 22 mV
during normal ”Closed Loop” operation for a total of
106.25 seconds over a 125–second period of time.

OR

D

Bank 1 HO2S 2 signal voltage remains below 426 mV
during power enrichment (P.E.) mode fuel control
operation for  5 seconds. 

The above conditions are met for 190 test failures in 220
test samples or 40 failures in 40 samples in P.E. mode
(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 Diagnostic Trouble Code set as Freeze
Frame and in the Failure Records data.

6E1–169

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

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 P0137 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

D

Diagnostic Trouble Code P0137 can be cleared by
using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

D

Heated oxygen sensor wiring – The sensor pigtail may
be mispositioned and/or contacting the exhaust
system.

D

Poor PCM to engine grounds.

D

Fuel pressure – A condition which causes a lean
exhaust can cause Diagnostic Trouble Code P0137 to
set. The system will go lean if pressure is too low. The
PCM can compensate for some decrease. However, if
fuel pressure is too low, a Diagnostic Trouble Code
P0137 may be set. Refer to Fuel System Diagnosis. 

D

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

D

Vacuum leaks – Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV system.

D

Exhaust leaks – An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the Diagnostic Trouble Code P0137 to
set. Check for exhaust leaks near the Bank 1 HO2S 2
sensor.

D

Fuel contamination – Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition. For
procedure to check for fuel contamination, refer to Fuel
System Diagnosis. 

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
3. Diagnostic Trouble Code P0137 being set in power

enrichment mode conditions may indicate a
condition described in the ”Diagnostic Aids” above.
If the Diagnostic Trouble Code P0137 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 P0137 – O2 Sensor Circuit Low 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 the parameters specified

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

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

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

26 mV

Go to Step 4 

Go to Step 3 

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 P0137 until the
Diagnostic Trouble Code P0137 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code
P0137 failed this ignition?

—

Go to Step 4 

Refer to

Diagnostic

Aids 

4

1. Turn ignition OFF.
2. Disconnect the PCM.
3. Check the Bank 1 HO2S 2 high and low signal

circuits for a short to ground or a short to the heater
ground circuit.

Were Bank 1 HO2S 2 signal circuits shorted?

—

Go to Step 5 

Go to Step 6 

6E1–170

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTC P0137 – O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)

  (Cont'd)

Step

No

Yes

Value(s)

Action

5

Repair the Bank 1 HO2S 2 signal circuit.

Is the action complete?

—

Verify repair

—

6

1. Ignition OFF.
2. Leave the PCM and HO2S 2 disconnected.
3. Check for continuity between the high and low

signal circuits.

Was there continuity between the high and low circuits?

—

Go to Step 7 

Go to Step 8 

7

Repair the short between the high and low circuits.

Is the action complete?

—

Verify repair

—

8

1. Ignition OFF.
2. Reconnect the PCM, leave HO2S 2 disconnected.
3. Ignition ON.

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

430–450 mV

Refer to

Diagnostic

Aids 

Go to Step 9 

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

—

6E1–171

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P0138 O2 SENSOR CIRCUIT HIGH 

VOLTAGE (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 1 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 excessively high for an
extended period of time, Diagnostic Trouble Code P0138
will be set.  DTC P0138 is a type A code.

Conditions for Setting the DTC

D

No related Diagnostic Trouble Codes.

D

Engine is operating in ”Closed Loop”.

D

”Closed Loop” commanded air/fuel ratio is between
14.5 and 14.8.

D

Engine coolant temperature is above 60

°

C (140

°

F).

D

Throttle angle is between 5.9% and 50%.
All above conditions met for 3.0 seconds or in
”Deceleration Fuel Cutoff” DFCO mode, and one of
the following two conditions are met:

D

Bank 1 HO2S 2 signal voltage remains above 952 mV
during normal ”Closed Loop” operation.

OR

D

Bank 1 HO2S 2 signal voltage remains above 474 mV
during deceleration fuel cutoff mode operation.

The above conditions are met for 190 test failures in 220
test samples or 40 fails in 40 samples in DFCO mode (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 Diagnostic Trouble Code 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.