Content .. 389 390 391 392 ..

Isuzu Rodeo UE. Manual - part 391

6E2–319

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0420 –TWC System Low Efficiency Bank 1

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

Are any other DTCs set (such as P0140, P0146)?

—

Diagnose

other DTC(s)

first

Go to

Step 3

1. Visually and physically inspect the three-way

catalytic converter for damage. Check for the
following:

dents

severe discoloration caused by excessive
temperatures

holes

internal rattle caused by damaged catalyst

2. Also, ensure that the three-way catalytic converter

is a proper original equipment manufacturer part.

Did your inspection reveal a problem?

—

Go to

Step 6

Go to

Step 4

1. Visually and physically inspect the exhaust system

between the three-way catalytic converter and the
rear converter flange for leaks, damage, and loose
or missing hardware.

2. If a problem is found, repair as necessary.

Did your inspection reveal a problem?

—

Go to

Step 7

to verify

repair

Go to

Step 5

1. Visually and physically inspect the Bank 1 HO2S 2.
2. Ensure that the Bank 1 HO2S 2 is secure and that

the pigtail and wiring harness is not contacting the
exhaust pipe or is not otherwise damaged.

3. If a problem is found, repair as necessary.

Did your inspection reveal a problem?

—

Go to

Step 7

to verify

repair

Go to

Step 6

Replace the three-way catalytic converter.

NOTE: Check for conditions which may cause catalyst
damage (refer to

Diagnostic Aids).

Is the action complete?

—

Go to

Step 7

to verify

repair

—

1. Review and record the Tech 2 Failure Records data.
2. Clear DTC P0420.
3. Start the engine and allow it to warm up until the

engine coolant temperature monitored on the Tech
2 is above the specified value.

4. Run the engine to maintain the specified mass air

flow range for at least 2 minutes.

5. Operate the vehicle to maintain DTC P0420 test

conditions (refer to

DTC Test Description in

Diagnostic Support for detailed instructions).

6. Using a Tech 2, monitor “DTC” info for DTC P0420

until the DTC P0420 test runs.

7. Note the test result.

Does the Tech 2 indicate DTC P0420 passed this
ignition?

Engine

coolant temp:

greater than

(140

F).

Mass air flow:

between 8

g/second and

50 g/second

Repair

complete. If

a driveability

symptom still

exists, refer

Symptoms.

Go to the

Diagnostic

Aids.

6E2–320

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0430 TWC System Low Efficiency Bank 2

T321075

Circuit Description

To control emissions of hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen (NOx), a
three-way catalyst (TWC) is used. The catalyst 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 2 HO2S 1 and the
Bank 2 HO2S 2 heated oxygen sensors. The Bank 2
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 2 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
2 HO2S 1 signal will be far more active than that produced
by the Bank 2 HO2S 2 sensor. If the PCM detects a level
of Bank 2 HO2S 2 activity that indicates the catalyst is no
longer operating efficiently, DTC P0430 will be set.

Conditions for Setting the DTC

No related DTCs.

The engine is operating in “closed loop.”

Engine air load is below 99%.

Engine coolant temperature is above 60

C (140

F).

Mass air flow is between 8 g/second and 50 g/second.

Change in engine load is below 8%.

Engine speed is below 3500 RPM.

Vehicle speed is between 26 km/h and 123 km/h (16
mph and 75 mph).

Catalyst temperature is above 399

C (750

F).

The PCM determines that the catalyst’s oxygen
storage capacity is below the acceptable threshold.

Action Taken When the DTC Sets

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

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 P0430 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0430 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
display on the Tech 2 while moving connectors and
wiring harnesses related to the sensor. A change in the
display will indicate the location of the fault.

Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.

Bank 2 HO2S 1/Bank 2 HO2S 2 Activity Test:
– Ensure that the engine is fully warmed up.
– Using a Tech 2, monitor Bank 2 HO2S 1 and Bank 2

HO2S 2 displays in “Park” while using the Tech 2 IAC
RPM control function to maintain a mass air flow of
10 g/second. Compare the amount of activity
(frequency and amplitude) on Bank 2 HO2S 1 to the
activity on Bank 2 HO2S 2 over a 30 second period.

If the amount of activity on Bank 2 HO2S 2 is nearly as
great as the activity on Bank 2 HO2S 1, a problem exists.
Use the DTC P0430 diagnostic chart. If much less activity
is noted on Bank 2 HO2S 2, the system is functioning
properly.

6E2–321

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
7. Difficulty completing the DTC P0430 “Status This

Ign.” test may be encountered in areas where test
conditions cannot be maintained easily, especially in
urban areas. To minimize the amount of driving
required to complete the DTC P0430 “Status This
Ign.” test, use the following procedure:

Allow the engine to warm completely.

With the vehicle in “Park,” monitor mass air flow on
the Tech 2 and hold part throttle to maintain a
reading of over 12 g/second for at least 2 minutes.
This will achieve the “warm catalyst” required for
running the test.

Operate the vehicle in second or third gear to remain
in the DTC P0430 test conditions described in
“Conditions for Setting the DTC” as much as
possible. If you must stop the vehicle, maintain the
“warm catalyst” criteria as follows:
– Place the vehicle in “Park” or “Neutral.”
– Hold part throttle to maintain a mass air flow

reading of over 15 g/second for the duration of the
stop.

The “TWC Monitor Test Counter” displayed on the Tech 2
may be used to monitor the progress of the TWC
diagnostic. To complete the TWC diagnostic with a good
catalyst, the counter must be allowed to increment to 49
samples and roll over to 0 at least twice.

6E2–322

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0430 –TWC System Low Efficiency Bank 2

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

Are any other DTCs set (such as P0160)?

—

Diagnose

other DTC(s)

first

Go to

Step 3

1. Visually and physically inspect the three-way

catalytic converter for damage. Check for the
following:

dents

severe discoloration caused by excessive
temperatures

holes

internal rattle caused by damaged catalyst

2. Also, ensure that the three-way catalytic converter

is a proper original equipment manufacturer part.

Did your inspection reveal a problem?

—

Go to

Step 6

Go to

Step 4

1. Visually and physically inspect the exhaust system

between the three-way catalytic converter and the
rear converter flange for leaks, damage, and loose
or missing hardware.

2. If a problem is found, repair as necessary.

Did your inspection reveal a problem?

—

Go to

Step 7

to verify

repair

Go to

Step 5

1. Visually and physically inspect the Bank 2 HO2S 1.
2. Ensure that the Bank 2 HO2S 2 is secure and that

the pigtail and wiring harness is not contacting the
exhaust pipe or is not otherwise damaged.

3. If a problem is found, repair as necessary.

Did your inspection reveal a problem?

—

Go to

Step 7

to verify

repair

Go to

Step 6

Replace the three-way catalytic converter.

NOTE: Check for conditions which may cause catalyst
damage (refer to

Diagnostic Aids).

Is the action complete?

—

Go to

Step 7

to verify

repair

—

1. Review and record the Tech 2 Failure Records data.
2. Clear DTC P0430.
3. Start the engine and allow it to warm up until the

engine coolant temperature monitored on the Tech
2 is above the specified value.

4. Run the engine to maintain the specified mass air

flow range for at least 2 minutes.

5. Operate the vehicle to maintain DTC P0430 test

conditions (refer to

DTC Test Description in

Diagnostic Support for detailed instructions).

6. Using a Tech 2, monitor “DTC” info for DTC P0430

until the DTC P0430 test runs.

7. Note the test result.

Does the Tech 2 indicate DTC P0430 passed this
ignition?

Engine

coolant temp:

greater than

(140

F).

Mass air flow:

between 8

g/second and

50 g/second

Repair

complete. If

a driveability

symptom still

exists, refer

Symptoms.

Go to the

Diagnostic

Aids.

Content .. 389 390 391 392 ..