1998 OPEL FRONTERA fuel pressure

6E–166
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0175 Fuel Trim System Rich Bank 2
D06RW031
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
HO2S 1 and Bank 2 HO2S 1 signals 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 2, the PCM will set DTC P0175.
The PCM’s maximum authority to control long term fuel
trim allows a range between –15%(automatic
transmission) or –12%(manual transmission) and +20%.
The PCM’s maximum authority to control short term fueltrim 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
No Tech 2 test is being run.
None of the following DTCs are set: idle system, EGR,
HO2S, (response, transition, open, low volts, no
activity), MAF, TPS, MAP, IAT, canister purge, EVAP,
injector circuit, or misfire.
Engine coolant temperature is between 25C (77F)
and 100C (212F).
Intake air temperature is between –40C (–40F) and
120
C (248F).
Manifold absolute pressure is between 24 kPa and 99
kPa.
Throttle angle is steady below 95%.
Vehicle speed is below 136 km/h (85 mph).
Engine speed is between 400 and 6,000 RPM.

6E–167 ENGINE DRIVEABILITY AND EMISSIONS
Barometric pressure is greater than 72.5 kPa.
Mass air flow is between 2 g/second and 200 g/second.
Ignition voltage is above 9.5 volts.
Fuel system is in “closed loop.”
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
failure 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
DTC P0175 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
Bank 2 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. DTCs other than P0172 and P0175 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/P0175.
4. If the DTC P0175 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.

6E–169 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0175 – Fuel Trim System Rich Bank 2
StepNo Ye s Va l u e ( s ) Action
111. 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 repairGo to Step 12
121. Ignition “ON,” engine “OFF.”
2. 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 13Go to Step 18
131. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in “closed loop” while
monitoring the “BANK 1 L.T. FUEL TRIM” and
“BANK 1 S.T. FUEL TRIM” display on the Tech 2.
Did both values change to near the specified value?
0%Go to Step 19Go to Step 14
141. Perform the “Fuel System Pressure Test.”
2. If Fuel System Pressure Test isolates a problem,
repair as necessary (refer to
Engine Fuel or Fuel
Metering System
).
Did the Fuel System Pressure Test isolate a condition
requiring repair?
—Verify repairGo to Step 16
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
161. Perform the “Injector Balance Test.”
2. If the Injector Balance Test isolates a problem,
repair as necessary (refer to
Fuel Metering
System
).
Did the Injector Balance Test isolate a problem
requiring repair?
—Verify repairGo to Step 17
171. Remove and visually/physically inspect the Bank 2
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 2 HO2S 1,
replace the contaminated sensor.
Did the sensor require replacement?
—Verify repair
Refer to
Diagnostic
Aids
181. 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—
19Replace the MAF sensor.
Is the action complete?
—Verify repair—

6E–246
ENGINE DRIVEABILITY AND EMISSIONS
amounts of fuel at idle, but may not be able to supply
enough fuel during heavy acceleration.
Water or alcohol in the fuel may cause low HO2S
voltage during acceleration.
Check for faulty or plugged fuel injector(s).
Check for low fuel.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.4. When the engine is idling or at steady cruise, the
HO2S voltage should vary from between
approximately 100 mV to 900 mV. It is possible to
measure a satisfactory fuel pressure at idle even
though the pressure may drop at high flow
requirements. It may be necessary to watch fuel
pressure at high engine load.
5. Wrap a shop towel around the fuel pressure
connector to absorb any small amount of fuel
leakage that may occur when installing gauge.
Ignition “ON,” pump pressure should be 280-320
kPa.
DTC P1171 – Fuel System Lean During Acceleration
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
2Are any component-related DTCs set?
—
Go to
component
DTC charts
Go to Step 3
31. Check the vehicle’s fuel tank for an adequate
amount of fuel.
2. Add fuel to the vehicle’s fuel tank if the tank is almost
empty.
Was fuel added to the vehicle’s fuel tank?
—Go to Step 4Go to Step 5
41. Place the transmission in park.
2. Using Tech 2, observe HO2S 1 voltage while
running warm engine 75
C-95C (167F-203F) at
1200 RPM.
3. HO2S 1 voltage should vary within the specified
range.
4. Quickly open the throttle halfway for a few seconds.
Did the voltage suddenly rise toward the high end of the
specified range?
100-900 mV
Go to Chart
A-7
Go to Step 5
51. Disconnect the fuel pump relay and crank the
engine to relieve the fuel pressure.
2. Install the fuel pressure gauge.
3. Start the engine and idle at normal operating
temperature.
4. Disconnect the vacuum line going to the fuel
pressure regulator.
With the engine running, is the fuel pressure within the
specified range?
280-325 kPa
(41-46 psi)
Go to OBD
System
Check
Go to Step 6
6Check for restricted fuel lines or restricted in-line filter.
Was a problem found?
—Verify repairGo to Step 7

6E–247 ENGINE DRIVEABILITY AND EMISSIONS
DTC P1171 – Fuel System Lean During Acceleration
StepNo Ye s Va l u e ( s ) Action
71. Ignition “OFF.”
2. Remove the fuel pump relay and replace it with a
fused jumper which will connect the relay’s battery
terminal to the terminal leading to the fuel pump
fuse.
3. While the fuel pump is operating, use pliers to slowly
close the return line (do not exceed the first
specified value).
Using the pliers to restrict the return line, can the fuel
pressure be manipulated to exceed the second
specified value?
414 kPa
(60 psi)
325 kPa
(46 psi)
Go to
Diagnostic
Aids
Go to Step 8
8Check for:
Faulty fuel pump
Restricted fuel pump strainer (sock)
Incorrect fuel pump
Incorrect fuel being used
Hot fuel
Is the action complete?
—Verify repair—

6E–251 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1508 IAC System Low RPM
T321115
Circuit Description
The powertrain control module (PCM) controls engine
idle speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional stepper
motor driven by two coils. The PCM applies current to the
IAC coils in steps (counts) to extend the IAC pintle into a
passage in the throttle body to decrease air flow. The
PCM reverses the current to retract the pintle, increasing
air flow. This method allows highly accurate control of idle
speed and quick response to changes in engine load. If
the PCM detects a condition where too low of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the IAC counts, DTC P1508 will set,
indicating a problem with the idle control system.
Conditions for Setting the DTC
No Tech 2 test is being run.
None of these DTCs are set: TP sensor, VSS, ECT,
EGR, fuel system, MAF, MAP, IAT, canister purge,
injector control or ignition control.
Barometric pressure is above 75 kPa.
Engine coolant temperature (ECT) is above 50C
(120
F).
Engine speed is more than 100-200 RPM lower than
desired idle, based upon coolant temperature.
The engine has been running for at least 125 seconds.
Vehicle speed is less than 1 mph.
Canister purge duty cycle is above 10%.
Ignition voltage is between 9.5 volts and 16.7 volts.
The throttle is closed.
Engine speed is lower than desired idle.
All of the above conditions are met for 10 seconds.
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.
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
DTC P1508 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 or IAC motor – 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 for damage.
Restricted air intake system – Check for a possible
collapsed air intake duct, restricted air filter element,
or foreign objects blocking the air intake system.
Throttle body – Check for objects blocking the IAC
passage or throttle bore, excessive deposits in the IAC

6E–254
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1509 IAC System High RPM
T321115
Circuit Description
The powertrain control module (PCM) controls engine
idle speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional stepper
motor driven by two coils. The PCM applies current to the
IAC coils in steps (counts) to extend the IAC pintle into a
passage in the throttle body to decrease air flow. The
PCM reverses the current to retract the pintle, increasing
air flow. This method allows highly accurate control of idle
speed and quick response to changes in engine load. If
the PCM detect a condition where too high of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the IAC counts, DTC P1509 will set,
indicating a problem with the idle control system.
Conditions for Setting the DTC
No Tech 2 test is being run.
None of these DTCs are set: TP sensor, VSS, ECT,
EGR, fuel system, MAF, MAP, IAT, canister purge,
injector control or ignition control.
Barometric pressure is above 75 kPa.
Engine coolant temperature is above 50C (120F).
Engine speed is more than 100-200 RPM lower than
desired idle, based upon coolant temperature.
The engine has been running for at least 125 seconds.
Vehicle speed is less than 1 mph.
Canister purge duty cycle is above 10%.
Ignition voltage is between 9.5 volts and 16.7 volts.
Engine speed is lower than desired idle.
All of the above conditions are met for 5 seconds.
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.
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
DTC P1509 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 or IAC motor – 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 for damage.
Vacuum leak – Check for a condition that causes a
vacuum leak, such as disconnected or damaged
h o s e s , l e a k s a t t h e E G R v a l v e a n d t h e E G R p i p e t o t h e
intake manifold, leaks at the throttle body, faulty or
incorrectly installed PCV valve, leaks at the intake
manifold, etc.

6E–263 ENGINE DRIVEABILITY AND EMISSIONS
Hard Start Symptom
StepActionVa l u e ( s )Ye sNo
1DEFINITION: Engine cranks, but does not start
for a long time. Does eventually run, or may start
but immediately stalls.
Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
—Verify repairGo to Step 3
3Was a visual/physical check performed?
—Go to Step 4
Go to
Visual/Physic
al Check
4Check engine coolant temperature (ECT) sensor for
shift in value. After 8 hours with the hood up and the
engine not running, connect Tech 2. With the ignition
“ON” and the engine not running, compare engine
coolant temperature to intake air temperature.
Are ECT and IAT within the specified value of each
other?
5C ( 9F)Go to Step 8Go to Step 5
51. Using Tech 2, display the engine coolant
temperature and note the value.
2. Check the resistance of the engine coolant
temperature sensor.
3. Refer to
Engine Coolant Temperature Sensor
Temperature vs. Resistance
chart on DTC P0118
Diagnostic Support
for resistance specifications.
Is the resistance value near the resistance for the
temperature noted?
—Go to Step 7Go to Step 6
6Replace the ECT sensor.
Is the action complete?
—Verify repair—
7Locate and repair high resistance or poor connection in
the ECT signal circuit or the ECT sensor ground.
Is the action complete?
—Verify repair—
81. Check for a faulty, plugged, or incorrectly installed
PCV valve.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 9
91. Check for water- or alcohol-contaminated fuel.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 10
101. Perform the procedure in Fuel System Pressure
Te s t
.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 11
111. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electric Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 12