Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1292

6E1–244

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P0402  EXHAUST GAS RECIRCULATION

(EGR) EXCESSIVE  FLOW DETECTED

060R100039

Circuit Description

The Powertrain Control Module (PCM) closes the
Exhaust Gas Recirculation (EGR) system on engine
start–up to test for excessive (any) flow. If the PCM
determines that EGR flow occurred on start–up, in two
consecutive trips, then DTC P0402 will set. DTC P0402 is
a type B code.

Conditions for Setting the DTC

D

Intake Air Temperature (IAT) is above 5

°

C (41

°

F).

D

Engine RPM is less than 500 RPM.

D

EGR Pintle Position if greater than 55 counts.

The above mentioned conditions must be met for 0.6
seconds during engine start–up on two consecutive trips.

Diagnostic Aids

Check for the following conditions:

D

Poor connection or damaged harness – Inspect the
wiring harness for damage. If the harness appears to
be OK, observe the Actual EGR Position display on the
Tech 2 while moving connectors and wiring harnesses
related to the EGR valve. A change in the display will
indicate the location of the fault.

D

Ensure EGR valve is correctly mounted. See
On–Vehicle Service.

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.

NOTE: If the EGR valve shows signs of excessive heat,
check the exhaust system for blockage (possible a
plugged catalytic converter) using the ”Restricted
Exhaust System Check.”

6E1–245

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTC P0402  EGR Excessive Flow Detected

 

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. Review and record the Tech 2 Failure Records data.
2. Clear Diagnostic Trouble Code and monitor the

Tech 2 System Info Screen while operating the
vehicle as specified in ”Diagnostic Aids.”

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

info for Diagnostic Trouble Code P0401 until the
Diagnostic Trouble Code P0401 test runs.

4. Note the test result.

Does the Tech 2 indicate Diagnostic Trouble Code
P0401 failed this ignition?

—

Go to

Diagnostic

Aids 

Go to Step 3 

3

1. Inspect the exhaust system for modification of

original installed parts or leaks.

2. If a problem was found, repair exhaust system as

necessary.

Was a condition present that required repair?

—

Verify repair

Go to Step 4 

4

1. Remove the EGR valve.
2. Visually and physically inspect the pintle, valve

passages and the adapter for excessive deposits or
any kind of a restriction.

3. If a problem if found, clean or replace EGR system

components as necessary.

Was a condition present that required repair?

—

Verify repair

Go to Step 5 

5

1. Remove the EGR inlet and outlet pipes from the

exhaust manifold and the intake manifold.

2. Inspect the manifold EGR ports and the EGR inlet

and outlet pipes for a blockage caused by excessive
deposits or other damage.

3. If a problem is found, correct the condition as

necessary.

Was a condition present that required repair?

—

Verify repair

Refer to

Diagnostic

Aids 

6E1–246

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P0404 EXHAUST GAS RECIRCULATION

(EGR) CIRCUIT RANGE/PERFORMANCE

060R100039

Circuit Description

An Exhaust Gas Recirculation (EGR) system is used to
lower Oxides of Nitrogen (NOx) emission levels caused
by high combustion temperatures.  It accomplishes this
by feeding small amounts of exhaust gases back into the
combustion chamber.  When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are
reduced.
A linear EGR valve is used on this system.  The linear
EGR valve is designed to accurately supply exhaust
gases to the engine without the use of intake manifold
vacuum.  The valve controls exhaust flow going into the
intake manifold from the exhaust manifold through an
orifice with a PCM controlled pintle.  The PCM controls
the pintle position using inputs from the Throttle Position
(TP) and Manifold Absolute Pressure (MAP) sensors.
The PCM then commands the EGR valve to operate
when necessary by controlling an ignition signal through
the PCM.  This can be monitored on a Tech 2 as the
Desired EGR Position.
The PCM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing
the EGR valve pintle position is sent to the PCM.  This
feedback signal can also be monitored on a Tech 2 and is
the actual position of the EGR pintle.  The Actual EGR
position should always be near the commanded or
Desired EGR Position.

If the PCM detects a large difference between the desired
EGR position and actual EGR position, then Diagnostic
Trouble Code P0404 will set.  DTC P0404 is a type B
code.

Conditions for Setting the DTC

D

IAT is greater than 5

°

C (41

°

F).

D

EGR commanded ON (EGR Position changes is less
than 3%).

D

Actual EGR Position and from Desired EGR.

Should be within 15% must fail more than 2 interaions for
5 second.
The above conditions are met 10 second.

Action Taken When the DTC Sets

D

Malfunction Indicator Lamp (MIL) will illuminate the
second time the fault is detected.

D

The PCM will record operating conditions at the time
the diagnostic fails.

D

A history Diagnostic Trouble Code is stored.

D

The EGR Valve is disabled.

Conditions for Clearing the MIL/DTC

D

The MIL will turn OFF after three consecutive ignition
cycles in which the diagnostic runs without a fault.

D

Diagnostic Trouble Code(s) can be cleared by using a
Tech 2.

6E1–247

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Diagnostic Aids

Due to the moisture associated with exhaust systems, the
EGR valve may freeze and stick in colder weather at
times.  After the vehicle is brought into a warm shop for
repairs, the valve warms and the problem disappears. By
watching the Actual EGR and Desired EGR Positions on
a cold vehicle with a Tech 2, the fault can be verified
easily.  Check the freeze frame data to determine if the
Diagnostic Trouble Code was set when the vehicle was
cold by viewing the Engine Coolant Temperature (ECT).

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1. The Powertrain OBD System Check prompts the

technician to complete some basic checks and store
the freeze frame and failure records data on the
Tech 2 if applicable.  This created an electronic copy
of the data taken when the fault occurred.  The
information is then stored on the Tech 2 for later
reference.

2. Commanding the EGR valve open determines

whether the EGR system can control the EGR valve
accurately and if the fault if present.

3. When the EGR valve electrical connector is

disconnected, the Tech 2 should display the Actual
EGR Position as 0%.  If is does not, the fault lies
either in the EGR signal circuit or the PCM.

4. A test light, when connected to ground, will glow

dimly when the EGR valve is commanded to 25%,
and brighter as the EGR valve is commanded to
100%.  If the test light flashes, check the sensor
ground for an open.

5. An open or poor connection condition may have

caused this Diagnostic Trouble Code to set.  Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor
tension.

7. The test light will have glowed brightly in the

previous step if the EGR control circuit was shorted
to B+ and the Actual EGR Position on the Tech 2
will display 100%.  A test light that did not illuminate,
indicates that the circuit may be open or shorted to
ground.

9. If the EGR valve 5 volt reference is shorted to

voltage, the DVM will read battery voltage and
additional Diagnostic Trouble Codes may be set and
engine performance will be poor.

12. The replacement PCM must be reprogrammed and

the Tooth Error Correction (TEC) procedure must be
performed.  Refer to the latest procedures for PCM
reprogramming and Powertrain Control Module for
the Tooth Error Correction (TEC) Procedure. 

13. Although the circuitry acted correctly when

checked, a problem may still lie within the terminals
which would not show up in probe type testing. Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor
tension.

17. All circuits to the EGR valve are OK at this point.

The fault lies internally in the EGR valve and
therefore must be replaced.  Be sure all gasket
material is removed from the EGR mounting
surface.  Even a small amount of material may
cause a Diagnostic Trouble Code P0401 to set.  For
on vehicle service of the EGR Valve, refer to EGR
Valve. 

18. Check the terminals for being backed out,

improperly formed or damaged, and for poor
tension.

19. Clearing the Diagnostic Trouble Codes is a very

important step for this diagnostic.  The clearing
function allows the EGR valve to relearn a new
pintle position as the old position was inaccurate
due to the malfunction that caused the Diagnostic
Trouble Code.  The Diagnostic Trouble Code must
be cleared with the ignition switch ON, with the
engine OFF or when the engine is idling.  If the
PCM sees a EGR command, the new pintle position
will not be learned.