2005 SUBARU IMPREZA WRX service

3-23
Instruments and controls
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If the light comes on while driving, it is unnecessary to
stop the vehicle, but avoid driving up steep grades or
in stop and go traffic. TAutomatic transmission control system warn- ing
If the light flashes after the engine starts, it may indi-cate that the automatic transmission control system is
not working properly. Contact your nearest SUBARU
dealer for service immediately. „ Rear differential oil temperature
warning light (WRX-STi)
Reduce vehicle speed and park the vehicle in a
safe place as soon as possible if the R.DIFF
TEMP light comes on. Continued driving with
this light on can damage the rear differential
and other parts of the powertrain.
If this light comes on when the engine is running, it
may indicate that the rear differential oil temperature is
too hot.
At this time, the driver’s control center differential will automatically cancel the current torque-distribution ra-
tio setting and adopts its minimum ratio.
If the light comes on while driving, reduce vehicle
speed and stop the vehicle at the nearest safe place.
Park the vehicle for several minutes. After the light
goes out, you can start driving.
If the light does not go out, contact the nearest
SUBARU dealer for service.
NOTE y
If the tire pressures are not correct and/or the
tires are not all the same size and brand, the rear
differential will be heavily loaded when the vehicle
is driven, resulting in an abnormally high oil tem-
perature.y The rear differential oil will deteriorate if its tem-
perature increases enough for the rear differential
oil temperature warning light to come on. It is ad-
visable to have the rear differential oil replaced as
soon as possible. „ ABS warning light
The ABS warning light comes on when the ignition
switch is turned to the “ON” position and goes out after
about two seconds.
This is an indication that the ABS system is working
properly.
(U.S.) (Canada)

4-18
Climate control
„
Cooling and dehumidifying in high hu-
midity and low temperature weather
conditions
Under certain weather conditions (high relative humid-
ity, low temperatures, etc.) a small amount of water
vapor emission from the air outlets may be noticed.
This condition is normal and does not indicate any
problem with the air conditioning system. „ Air conditioner compressor shut-off
when engine is heavily loaded
To improve acceleration and gas mileage, the air con-
ditioner compressor is designed to temporarily shut off
during air conditioner operation whenever the acceler-
ator is fully depressed such as during rapid accelera-
tion or when driving on a steep upgrade. „ Refrigerant for your climate control
system
Your air conditioner uses ozone friendly refrigerant
HFC134a. Therefore, the method of adding, changing
or checking the refrigerant is different from the method
for CFC12 (Freon). Consult your SUBARU dealer for
service. Repairs needed as a result of using the wrong
refrigerant are not covered under warranty. Air filtration system (Turbo model
only)
If your vehicle’s air conditioning system is equipped
with an air filtration system, replace the filter element
according to the replacement schedule shown below.
This schedule should be followed to maintain the fil-
ter’s dust collection ability. Under extremely dusty con-
ditions, the filter should be replaced more frequently. It
is recommended that you have your filter checked or
replaced by your SUBARU dealer. For replacement,
use only a genuine SUBARU air filter kit.
Replacement schedule:
Every 12 months or 7,500 miles (12,000 km) whichev-
er comes first

4-21
Climate control
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5. Reinstall the air filter cover. 6. Connect the connector, and reinstall the glove box.
7. Close the glove box.
1) Service label
2) Caution label
8. LABEL installation 1) Fill out the information on the service label
(small).
2) Attach the service label to the driver side door pil-
lar and the caution label to the driver side end of the
instrument panel.
Contact your dealer if the following occurs,
UG4052CA
UG4051BA
2 1
UG4068BB

7-2
Starting and operating
Starting and operatingFuel
Use of a fuel which is low in quality or use of an
inappropriate fuel additive may cause engine
damage.
„ Fuel requirements
T 2.5-liter non-turbo models
The 2.5-liter non-turbo engine is designed to operate
using unleaded gasoline with an octane rating of 87
AKI or higher. T 2.0-liter turbo models
The 2.0-liter turbo engine is designed to operate using
premium unleaded gasoline with an octane rating of
91 AKI or higher. If premium unleaded gasoline is not
available, regular unleaded gasoline with an octane
rating of 87 AKI or higher may be temporarily used.
For optimum engine performance and driveability, it is
required that you use premium grade unleaded gaso-
line. T
2.5-liter turbo model
The 2.5-liter turbo engine is designed to operate using
super-premium unleaded gasoline with an octane rat-
ing of 93 AKI or higher. If super-premium unleaded
gasoline with an octane rating of 93 AKI or higher is
not available, premium unleaded gasoline with an oc-
tane rating of 91 AKI or higher can be used. For opti-
mum engine performance and driveability, it is recom-
mended that you use super-premium grade unleaded
gasoline with an octane rating of 93 AKI or higher. T Fuel octane rating
This octane rating is the average of the Research Oc-
tane and Motor Octane numbers and is commonly re-
ferred to as the Anti Knock Index (AKI).
Using a gasoline with a lower octane rating can cause
persistent and heavy knocking, which can damage the
engine. Do not be concerned if your vehicle some-
times knocks lightly when you drive up a hill or when
you accelerate. See your dealer or a qualified service
technician if you use a fuel with the specified octane
rating and your vehicle knocks heavily or persistently. T Unleaded gasoline
The neck of the fuel filler pipe is designed to accept
only an unleaded gasoline filler nozzle. Under no cir-
cumstances should leaded gasoline be used because
it will damage the emission control system and may

7-3
Starting and operating
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impair driveability and fuel economy. TGasoline for California-certified LEV
Your vehicle was certified to California’s low emission
vehicle (LEV) standards as indicated on the under-
hood tune-up label. It is designed to optimize engine
and emission performance with gasoline that meets
the clean burning low-sulfur California gasoline speci-
fications. If you live in any other state than California,
your vehicle will operate on gasoline meeting Federal
specifications. Gasoline sold outside California is per-
mitted to have higher sulfur levels, which may affect
the performance of your vehicle’s catalytic converter
and may produce a sulfur exhaust odor or smell.
SUBARU recommends that you try a different brand of
unleaded gasoline having lower sulfur to determine if
the problem is fuel related before returning your vehi-
cle to an authorized dealer for service. T MMT
Some gasoline contains an octane-enhancing additive
called MMT (Methylcyclopentadienyl Manganese Tri-
carbonyl). If you use such fuels, your emission control
system performance may deteriorate and the CHECK
ENGINE warning light/Malfunction indicator lamp may
turn on. If this happens, return to your authorized
SUBARU Dealer for service. If it is determined that the
condition is caused by the type of fuel used, repairs may not be covered by your warranty. T
Gasoline for cleaner air
Your use of gasoline with detergent additives will help
prevent deposits from forming in your engine and fuel
system. This helps keep your engine in tune and your
emission control system working properly, and is a
way of doing your part for cleaner air. If you continu-
ously use a high quality fuel with the proper detergent
and other additives, you should never need to add any
fuel system cleaning agents to your fuel tank.
Many gasolines are now blended with materials called
oxygenates. Use of these fuels can also help keep the
air cleaner. Oxygenated blend fuels, such as MTBE
(Methyl Tertiary Butyl ether) or ethanol (ethyl or grain
alcohol) may be used in your vehicle, but should con-
tain no more than 15% MTBE or 10% ethanol for the
proper operation of your SUBARU.
In addition, some gasoline suppliers are now produc-
ing reformulated gasolines, which are designed to re-
duce vehicle emissions. SUBARU approves the use of reformulated gasoline.
If you are not sure what the fuel contains, you should
ask your service station operators if their gasolines
contain detergents and oxygenates and if they have
been reformulated to reduce vehicle emissions.

7-4
Starting and operating
As additional guidance, only use fuels suited for your
vehicle as explained below.y
Fuel should be unleaded and have an octane rating
no lower than that specified in this manual.y Methanol (methyl or wood alcohol) is sometimes
mixed with unleaded gasoline. Methanol can be used
in your vehicle ONLY if it does not exceed 5% of the
fuel mixture AND if it is accompanied by sufficient
quantities of the proper cosolvents and corrosion in-
hibitors required to prevent damage to the fuel system.
Do not use fuel containing methanol EXCEPT under
these conditions. y If undesirable driveability problems are experienced
and you suspect they may be fuel related, try a differ-
ent brand of gasoline before seeking service at your
SUBARU dealer. y Fuel system damage or driveability problems which
result from the use of improper fuel are not covered
under the SUBARU Limited Warranty.
Do not let fuel spill on the exterior surfaces of
the vehicle. Fuels containing alcohol may
cause paint damage, which is not covered un-
der the SUBARU Limited Warranty. „
Fuel filler lid and cap
T Refueling
0
UG7501BA

7-7
Starting and operating
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State emission testing (U.S. only)
At state inspection time, remember to tell your in-
spection or service station in advance not to place
your Subaru AWD vehicle on a two-wheel dyna-
mometer. Otherwise, serious transmission dam-
age will result.
Some states have started using dynamometers in
their state inspection programs in order to meet their
obligation under federal law to implement stricter vehi-
cle emission standards to reduce air pollution from ve-
hicles. A dynamometer is a treadmill or roller-like test-
ing device that allows your vehicle’s wheels to turn
while the vehicle remains in one place. Depending on
the severity of a state’s air pollution problems, the
states must adopt either a “basic” or “enhanced” vehi-
cle emission inspection test. Normally, a portion of the
basic emission test consists of an emission inspector
inserting an analyzer probe into the exhaust pipe of an
idling vehicle for a short period of time. States with
more severe air pollution problems are required to
adopt an enhanced vehicle emission test. This test
simulates actual driving conditions on a dynamometer
and permits more accurate measurement of tailpipe
emitted pollution than the basic emission test.
The U.S. Environmental Protection Agency (EPA) and states using two-wheel dynamometers in their emis-
sion testing programs have
EXEMPTED Subaru AWD
vehicles from the portion of the testing program that in-
volves a two-wheel dynamometer.
There are some states that use four-wheel dynamom-
eters in their testing programs. When properly used,
that equipment will not damage an AWD Subaru vehi- cle.
Under no circumstances should the rear wheels be
jacked off the ground, nor should the driveshaft be dis-
connected for state emission testing.
Testing of an All-Wheel Drive vehicle must
NEVER be performed on a single two-wheel dy-
namometer. Attempting to do so will result in
uncontrolled vehicle movement and may cause
an accident or injuries to persons nearby.
Resultant vehicle damage due to improper test-
ing is not covered under the SUBARU Limited
Warranty and is the responsibility of the state

7-8
Starting and operating
inspection program or its contractors or licens-
ees.
The EPA has issued regulations for inspecting the On-
Board Diagnostic (OBD) system as part of the state
emissions inspection. The OBD system is designed to
detect engine and transmission problems that might
cause vehicle emissions to exceed allowable limits.
These inspections apply to all 1996 model year and
newer passenger cars and light tracks. Several states
plus the District of Columbia have opted to start the
OBD system inspection prior to the required EPA reg-
ulation effective date of January 1, 2002. Other states
will add OBD system inspection in 2002. y The inspection of the OBD system consists of a vi-
sual operational check of the “ CHECK ENGINE” warn-
ing light/malfunction indicator lamp (MIL) and an ex-
amination of the OBD system with an electronic scan
tool while the engine is running. y A vehicle passes
the OBD system inspection if
proper the “ CHECK ENGINE ” warning light/MIL illumi-
nation is observed, there is no stored diagnostic trou-
ble codes, and the OBD system readiness monitors
are complete. y A vehicle fails
the OBD inspection if the “ CHECK
ENGINE ” warning light/MIL is not properly operating or there is one or more diagnostic trouble codes stored
in vehicle’s computer with the “
CHECK ENGINE”
warning light/MIL illuminated. y A state emission inspection may reject (not pass or
fail) a vehicle if the number of OBD system readiness monitors “ Not Ready ” is greater than three. Under this
condition, the vehicle operator should be instructed to
drive his/her vehicle for a few days to set the monitors
and return for an emission re-inspection. y Owners of rejected or failing vehicles should contact
their Subaru Dealer for service.