Isuzu Rodeo UE. Manual — part 201
6E1–175
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0172 SYSTEM TOO RICH (BANK 1)
D06RX048
Circuit Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a ”Closed Loop”
air/fuel metering system is used. While in ”Closed Loop”,
the powertrain control module (PCM) monitors the Bank 1
heated oxygen sensor (HO2S) 1 and adjusts fuel delivery
based upon the HO2S signal voltages. A change made to
fuel delivery will be indicated by the long and short term
fuel trim values which can be monitored with a Tech 2.
Ideal fuel trim values are around 0%; if the HO2S signals
are indicating a lean condition the PCM will add fuel,
resulting in fuel trim values above 0%. If a rich condition is
detected, the fuel trim values will be below 0%, indicating
that the PCM is reducing the amount of fuel delivered. If
an excessively rich condition is detected on Bank 1, the
PCM will set Diagnostic Trouble Code P0172. DTC
P0172 is a type B code.
The PCM’s maximum authority to control long term fuel
trim allows a range between –14% and +20%. The PCM’s
maximum authority to control short term fuel trim allows a
range between –11% and +20%. The PCM monitors fuel
trim under various engine speed/load fuel trim cells
before determining the status of the fuel trim diagnostic.
Conditions for Setting the DTC
f
No Tech 2 test is being run.
f
None of the following was set: EGR Diagnostic Trouble
Codes, HO2S Diagnostic Trouble Codes, (response,
transition, open, low volts, no activity), TPS Diagnostic
Trouble Codes, MAP Diagnostic Trouble Codes, IAT
Diagnostic Trouble Codes, canister purge Diagnostic
Trouble Codes, EVAP Diagnostic Trouble Codes,
injector circuit Diagnostic Trouble Codes, or misfire
Diagnostic Trouble Codes.
f
Engine coolant temperature is between 65
°
C (149
°
F)
and 104
°
C (219
°
F).
f
Intake air temperature is between –40
°
C (–40
°
F) and
120
°
C(248
°
F).
f
Manifold absolute pressure is between 23.75 kPa and
99 kPa.
f
System voltage is greater than 9.5 volts.
f
Engine speed is between 400 and 6000 RPM.
f
Barometric pressure is greater than 72.3 kPa.
f
Engine is operating in ”Closed Loop”.
f
The average of the long term full trim samples is less
than 1.03 and the average of the adaptive index
multiplier samples is less than or equal to 0.82.
Action Taken When the DTC Sets
f
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
f
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
f
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.
6E1–176
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
f
A history Diagnostic Trouble Code P0172 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.
f
Diagnostic Trouble Code P0172 can be cleared by
using the Scan Tool’s ”Clear Info” function.
Diagnostic Aids
Check for the following conditions:
f
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.
f
Damaged harness – Inspect the wiring harness for
damage; shorts to ground, shorts to battery positive
and open circuits. If the harness appears to be OK,
observe the Bank 1 HO2S 1 display on the Tech 2 while
moving connectors and wiring harnesses related to the
engine harness. 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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Diagnostic Trouble Codes other than P0172 may
indicate a condition present which may cause a lean
condition. If this is the case, repairing the condition
which caused the other DTC will most likely correct
the DTC P0172.
4. If the Diagnostic Trouble Code P0172 test passes
while the Failure Records conditions are being
duplicated, the rich condition is intermittent. Refer to
Diagnostic Aids or Symptoms for additional
information on diagnosing intermittent problems.
—
6E1–177
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DTC P0172 – System Too Rich (Bank 1)
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
Are any Diagnostic Trouble Codes set other than
P0172?
—
Go to the
applicable
DTC charts
and repair the
other DTCs
before
proceeding
with this
chart.
Go to Step 3
3
1. Start the engine and operate the vehicle in ”Closed
Loop”.
2. Observe ”BANK 1 L.T. FUEL TRIM” display on the
Tech 2.
Are the displayed values more negative than the
specified values?
L.T. Fuel
Trim: –14%
Go to Step 5
Go to Step 4
4
1. Review and record the Tech 2 Failure Records data.
2. Clear the Diagnostic Trouble Code P0172 and
operate the vehicle to duplicate the Failure Records
conditions.
3. Monitor the Tech 2 “Diagnostic Trouble Code” info
for Diagnostic Trouble Code P0172 while operating
the vehicle to duplicate the Failure Records
conditions.
4. Continue operating the vehicle until the Diagnostic
Trouble Code P0172 test runs and note test result.
Does the Tech 2 indicate Diagnostic Trouble Code
P0172 failed this ignition?
—
Go to Step 5
The rich
condition is
not present. If
a driveability
symptom still
exists, refer
to Symptoms.
5
Visually and physically inspect the air filter element and
replace it if necessary.
Did the air filter require replacement?
—
Verify repair
Go to Step 6
6
Visually and physically inspect the air intake duct for
collapse or restriction and repair if necessary.
Did your inspection reveal a condition requiring repair?
—
Verify repair
Go to Step 7
7
Start the engine and note the idle quality.
Is a low or unsteady idle being experienced?
—
Go to Step 8
Go to Step
10
8
With the engine idling, observe the ”IDLE AIR
CONTROL” display on the Tech 2.
Is the ”IDLE AIR CONTROL” value below the specified
value?
Below 100
counts
Go to Step
10
Go to Step 9
9
1. Ignition OFF.
2. Physically inspect the throttle body bore, throttle
plate, and IAC passages for coking and foreign
objects.
3. If a problem was found, repair as necessary.
Did your inspection reveal a condition requiring repair?
—
Verify repair
Go to Step
10
6E1–178
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DTC P0172 – System Too Rich (Bank 1)
(Cont'd)
Step
No
Yes
Value(s)
Action
10
1. Perform the ”Idle Air Control (IAC) Valve Check.”
2. If a problem is found, repair as necessary.
Did the test isolate a problem requiring repair?
—
Verify repair
Go to Step
11
11
1. Disconnect the vacuum hose from the fuel pressure
regulator and inspect the hose for the presence of
fuel.
2. If fuel is present in the vacuum hose, replace the
fuel pressure regulator (refer to Fuel Metering
System).
Did the fuel pressure regulator require replacement?
—
Verify repair
Go to Step
12
12
Ignition ON engine OFF monitor the TP Angle display
on the Tech 2 while slowly depressing the accelerator
pedal.
Does the TP Angle display increase steadily and
evenly from minimum value at closed throttle to
maximum value at wide–open throttle?
Minimum 0%
Maximum
100%
Go to Step
13
Go to Step
17
13
1. Perform the ”Fuel System Pressure Test.”
2. If the test isolates a problem, repair as necessary
(refer to Engine Fuel or Fuel Metering System).
Did the test isolate a problem requiring repair?
—
Verify repair
Go to Step
14
14
1. Perform the ”Evaporative Emissions Control
(EVAP) Canister Purge Valve Check.”
2. If the test isolates a problem, repair as necessary.
Did the test isolate a problem requiring repair?
—
Verify repair
Go to Step
15
15
1. Perform the ”Injector Balance Test.”
2. If the test isolates a problem, repair as necessary
(refer to Fuel Metering System).
Did the test isolate a problem requiring repair?
—
Verify repair
Go to Step
16
16
1. Remove and visually/physically inspect the Bank 1
HO2S 1 for silicon contamination. This will be
indicated by a powdery white deposit on the portion
of the HO2S that is exposed to the exhaust stream.
2. If contamination is evident on the Bank 1 HO2S 1,
replace the contaminated sensors.
Did the sensor require replacement?
—
Verify repair
Refer to
Diagnostic
Aids
17
1. Check the TP sensor mounting screws and tighten
or replace them as necessary if they are loose or
missing.
2. If the screws are OK, replace the TP sensor.
Is the action complete?
—
Verify repair
—
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