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Isuzu Trooper (1998-2002 year). Manual - part 496

6E–354

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

DTC P1125 – ETC Limit Performance Model

(Cont'd)

Step

Yes

Value(s)

Action

Replace the AP sensor.

Was a problem corrected?

—

Verify repair

Go to

Step 8

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.Refer to

ON-Vehicle Service in Power

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 replasement PCM.

Is the action complete?

—

Verify repair

—

6E–355

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC)

P1133 HO2S Insufficient Switching Bank 1 Sensor 1

D06R200010

Circuit Description

The powertrain control module (PCM) monitors the
heated oxygen sensor (HO2S) activity for 90 seconds
after “closed loop” and stoichiometric operation have
been enabled. During this test period the PCM counts the
number of times that the HO2S signal voltage crosses the
rich-to-lean and lean-to-rich threshold. If the PCM
determines that the HO2S did not switch enough times,
DTC P1133 will be set.
A lean-to-rich switch is determined when the HO2S
voltage changes above and below 450 mV.
Heated oxygen sensors are used to minimize the amount
of time required for “closed loop” fuel control operation
and to allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank
2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature for accurate exhaust oxygen
content readings further from the engine.

Conditions for Setting the DTC

Engine coolant temperature (ECT) is above 60

(140

F).

Engine is operating in “closed loop”.

The engine has been running at least one minute.

Canister purge duty cycle is greater than 2%.

Engine speed is between 1500 RPM and 3000 RPM.

Mass air flow (MAF) is between 9 g/second and 42
g/second.

Above conditions are present for 3 seconds.

90 seconds after “closed loop” and stoichiometric
operation have been achieved, the PCM monitors the
oxygen sensor as it switches above and below 450 mV.
If fewer than 23 rich-to-lean and lean-to-rich switches
are detected, DTC P1133 will be set.

Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.

”Open loop” fuel control will be in effect.

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

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.

A history DTC P1133 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1133 can be cleared by using Tech 2 “Clear Info”
function or by disconnecting the PCM battery feed.

6E–356

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Aids

A malfunction in the HO2S heater ignition feed or ground
circuit may cause a DTC P1133 to set. Check HO2S
heater circuitry for intermittent faults or poor connections.
If connections and wiring are OK and DTC P1133
continues to set, replace the Bank 1 HO2S 1.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help to determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.

3. A condition that affects other heated oxygen sensors

indicates probable contamination. To avoid
damaging the replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.

5. This step checks for conditions which may cause the

heated oxygen sensor to appear faulty. Correct any
of the described conditions if present.

11.To avoid damaging replacement sensors, correct the

condition which caused the contamination before
replacing the affected sensors.

DTC P1133 – HO2S Insufficient Switching Bank 1 Sensor 1

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

IMPORTANT: If any DTCs are set (except P1153 or
P1154) refer to those DTCs before proceeding with this
diagnostic chart.

1. Engine idling at operating temperature.
2. Operating the vehicle within parameters specified

under “Conditions for Setting the DTC” criteria
included in Diagnostic Support.

3. Using a Tech 2, monitor “DTC” info for DTC P1133

until the DTC P1133 test runs.

4. Note the test result.

Does the Tech 2 indicate DTC P1133 failed this
ignition?

—

Go to

Step 3

Check the

Procedure

Refer to

Diagnostic

Aids

Did the Tech 2 also indicate that the P1153 or P1154
tests failed?

—

Go to

Step 20

Go to

Step 4

Check for leaks at the exhaust pipe joints.

Are the joints leaking?

—

Go to

Step 5

Go to

Step 6

Tighten the bolt/nuts at the leaking joints.

Is your action complete?

—

Go to

Step 2

—

Check for gaskets that are damaged or improperly
installed.

Are there damaged or misaligned gaskets?

—

Go to

Step 7

Go to

Step 8

1. Replace the damaged gaskets.
2. Align the connections.
3. Tighten the connections.

Is your action complete?

—

Go to

Step 2

—

Check for loose exhaust flange connections.

Are the flange connections loose?

—

Go to

Step 9

Go to

Step 10

Tighten the stud nuts or bolts to specifications.

Is your action complete?

—

Go to

Step 2

—

Check for burned or corroded exhaust pipes.

Are the exhaust pipes burned or corroded?

—

Go to

Step 11

Go to

Step 12

6E–357

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1133 – HO2S Insufficient Switching Bank 1 Sensor 1

(Cont'd)

Step

Yes

Value(s)

Action

Replace the exhaust pipes, as required.

Is your action complete?

—

Go to

Step 2

—

Check for leaks at the exhaust manifold.

Are there leaks at the exhaust manifold?

—

Go to

Step 13

Go to

Step 14

Tighten the bolts to specifications or replace the
manifold if necessary.

Is your action complete?

—

Go to

Step 2

—

Visually/physically inspect the following items:

Ensure that the Bank 1 HO2S 1 is securely
installed.

Check for corrosion on the terminals.

Check the terminals at Bank 1 HO2S 1 and at the
PCM.

Check for damaged wiring.

Was a problem found in any of the above areas?

—

Verify repair

Go to

Step 15

1. Disconnect Bank 1 HO2S 1.
2. Ignition “ON”.
3. Using a DVM at the PCM side of the connector,

check the voltage between the high signal circuit
and ground. Also measure between the low signal
circuit and ground.

Are both voltages in the specified range?

3-4 mV

Go to

Step 18

Go to

Step 16

1. Ignition “OFF”.
2. Check for damage to PCM pins or terminals.

Was a problem found.

—

Verify repair

Go to

Step 17

Check for a short to voltage or ground or an open in the
signal circuit.

Was a problem found?

—

Verify repair

Go to

Step 18

1. Ignition “OFF”.
2. Disconnect the PCM connector.
3. With the HO2S disconnected, check for high and

low signal circuits shorted together between the
PCM and HO2S.

Was a problem found?

—

Verify repair

Go to

Step 19

With the PCM connected and Bank 1 HO2S 1
disconnected from the harness, check Bank 1 HO2S 1
with a Tech 2.

Is the voltage in the specified range?

425-475 mV

Go to

Step 21

Go to

Step 22

Replace the affected heated oxygen sensors.

NOTE: Before replacing the sensors, the cause of the
contamination must be determined and corrected.

Fuel contamination

Use of improper RTV sealant.

Engine oil/coolant consumption.

Is the action complete?

—

Verify repair

—

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