2008 AUDI A4 check engine light

Checking and topping up fluids 254Checking and topping up fluidsBonnetReleasing the bonnet
The bonnet is released from inside the vehicle.– Open the driver's door.
– Pull the lever under the dashboard in the direction indi-
cated (arrow) ⇒fig. 250.The bonnet springs out of its lock.
Opening the bonnetBefore opening the bonnet make sure that the windscreen
wiper arms are not lifted away from the glass. Otherwise the
paint may get damaged.
– Lift the bonnet slightly ⇒.
– Press the release catch under the bonnet upwards
⇒fig. 251. This will release the arrester hook.
– Open the bonnet.The bonnet is held open by two gas-filled struts.
WARNING
To avoid the risk of being scalded, never open the bonnet if you see
steam or coolant escaping from the engine compartment. Wait
until no steam or coolant can be seen before opening the bonnet.
Fig. 250 Detail of foot-
well on driver's side:
Release lever
Fig. 251 Release catch
under the bonnet
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Checking and topping up fluids261
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
•
The coolant additive G12++ can be mixed only with additives
G12+ and G12.
Checking coolant level
The coolant level can be checked at a glance.– Switch off the ignition.
– Read off coolant level on radiator expansion tank
⇒fig. 257. When the engine is cold it should be between
the “MIN” and “MAX” marks. When the engine is hot it
may be slightly above the “MAX” mark.The coolant level should be checked with the engine switched off.
The coolant level is monitored by a warning lamp in the instrument
cluster ⇒page 33. However, we recommend that it should be
checked occasionally.
Coolant losses
Any loss of coolant normally indicates a leak in the cooling system.
In this case the cooling system should be inspected by a qualified
workshop without delay. It is not sufficient merely to top up the
coolant.If there are no leaks in the system, a loss of coolant can only occur
if the coolant boils and is forced out of the system as a result of
overheating.
Caution
Radiator sealants must not be added to the coolant. Such additives
could seriously impair the function of the cooling system.Topping up the coolant
Be careful when topping up coolant.– Switch off the engine.
– Wait for the engine to cool down.
– Cover the cap on the expansion tank ⇒fig. 257 with a
cloth, and carefully unscrew the cap anti-clockwise
⇒.
– Add coolant.
– Screw the cap on again tightly.Make sure that the coolant meets the required specifications
⇒page 260, “Coolant”. Do not use a different type of additive if anti-
freeze additive G12++, G12+ or G12 is not available. In this case use
only water and bring the coolant concentration back up to the
correct level as soon as possible by putting in the specified additive.
Always top up with fresh, unused coolant.
Do not fill above the “MAX” mark. Excess coolant is forced out of the
system through the valve in the filler cap when the engine gets hot.
If a lot of coolant has been lost, wait for the engine to cool down
before putting in cold coolant. Failure to do so could result in
serious engine damage.
Fig. 257 Engine
compartment: Mark-
ings on radiator expan-
sion tank
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Checking and topping up fluids 262
WARNING
•
The cooling system is under pressure. Do not unscrew the cap
on the expansion tank when the engine is hot: you could be
scalded by escaping steam
•
The coolant and coolant additive can be a health hazard. Store
the coolant additive in the original container in a safe place out of
reach of children – risk of poisoning.For the sake of the environment
Drained off coolant should not be used again. Drain off the used
coolant into a suitable container and dispose of it in the proper
manner (observe environmental regulations).Radiator fan
The radiator fan can start running spontaneously.The radiator fan is driven by the engine via a poly V-belt. The speed
of the fan is varied by a viscous clutch according to the temperature.
There is also an auxiliary electric fan, which cuts in automatically
whenever the temperature of the coolant and the engine compart-
ment rises above a certain level.
The auxiliary fan can continue to run for as long as 10 minutes after
stopping the engine – even after the ignition is switched off. It may
also start running suddenly ⇒ after a while if•
residual heat raises the coolant temperature, or
•
the hot engine compartment is additionally heated up by the
sun.
WARNING
When working in the engine compartment be aware that the radi-
ator fan may start running suddenly – risk of injury.
Brake fluidChecking brake fluid level
The brake fluid level can be checked at a glance.– Check the fluid level on the brake fluid reservoir
⇒fig. 258. It should always be between the “MIN” and
“MAX” marks.In right-hand drive vehicles the brake fluid reservoir is on the other
side of the engine compartment.
The fluid level may drop slightly after a period of time due to the
automatic compensation for brake pad wear. This is quite normal.
However, if the level goes down noticeably in a short time, or drops
below the “MIN” mark, there may be a leak in the brake system. If
the fluid level in the reservoir is too low, this will be indicated by the
brake warning lamp ⇒page 32. If this should happen, take the car
to a qualified workshop immediately and have the brake system
inspected.
Fig. 258 Engine
compartment: Mark-
ings on brake fluid
reservoir
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Checking and topping up fluids 264Please note that certain convenience features, such as the Audi
advanced key*, the remote control key or the electrical seat adjust-
ment may not be available when you unlock the vehicle. These func-
tions will be restored when you switch on the ignition and start the
engine.
Winter conditions
At low temperatures the battery has to work very hard. It also
provides only a fraction of the starting power it has at normal
temperatures.
For this reason, we recommend having the battery checked and
charged if necessary before the start of winter ⇒page 265.
WARNING
•
All work on batteries requires specialist knowledge. For queries
regarding the vehicle battery please contact an Audi dealership or
other qualified workshop (risk of chemical burns / risk of explo-
sion).
•
The battery must not be opened. Do not attempt to make any
changes to the electrolyte level of the battery. Otherwise, there is
a risk that a mixture of oxygen and hydrogen gas can accumulate
and cause an explosion.Note
If the vehicle is to be left standing for a period of several weeks at
extremely low temperatures, the battery should be removed from
the vehicle. This ensures that it cannot “freeze up” and be
damaged.
Important safety warnings for handling a car battery
All work on batteries requires specialist knowledge.The vehicle battery is located under the floor panel in the luggage
compartment.
WARNING
Always be aware of the danger of injury and chemical burns as
well as the risk of accident or fire when working on the battery and
the electrical system.•
Wear safety glasses. Do not allow acid or lead particles to come
into contact with eyes, skin or clothing.
•
Battery acid is extremely corrosive. Wear protective gloves and
safety glasses. Do not tilt the battery - acid can leak out of the
vapour vent. If electrolyte should splash into the eyes rinse at once
for several minutes using clear water. Then seek medical care
immediately. Neutralize any acid splashes on the skin or clothing
with soap solution, and rinse off with plenty of water. If acid is
swallowed by mistake, consult a doctor immediately.
•
Keep open flames, sparks, uncovered lights and lit cigarettes
away from battery. Avoid sparks (including those from static

Wear safety glasses!

Battery acid is extremely corrosive. Wear protec-
tive gloves and safety glasses.

Keep open flames, sparks, uncovered lights and
lit cigarettes away from battery!

A highly explosive mixture of gases is given off
when the battery is under charge!

Keep children away from the battery and battery
acid.
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Checking and topping up fluids265
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data charges) when handling cables and electrical equipment. Never
cross the battery poles. The resulting high-energy sparks can
cause injury.
•
A highly explosive mixture of gases is given off when the
battery is under charge. Only charge battery in a well ventilated
area.
•
Keep children away from the battery and battery acid.
•
Switch off all electrical equipment before starting any work on
the vehicle electrical system. Remove the ignition key. The minus
cable of the battery must be disconnected. When changing a light
bulb, it is sufficient to only turn off the light.
•
Before disconnecting the battery, turn off the anti-theft
system! Otherwise, the alarm will sound.
•
When disconnecting the battery from the vehicle's electrical
system, first disconnect the minus cable and then the plus cable.
•
Before reconnecting the battery, turn off all electrical equip-
ment. First connect the plus cable, then the minus cable. The
battery cables must not be connected to the wrong battery poles
- serious risk of cable fire.
•
Never charge a frozen or thawed out battery - risk of explosion
and chemical burns! A battery must be replaced once it has been
frozen. When it is discharged the battery can freeze at tempera-
tures around 0°C.
•
Make sure that the vapour hose is always attached to the
battery.
•
Never use a damaged battery - risk of explosion! Replace a
damaged battery immediately.Caution
•
Never disconnect the car's battery with the engine running or
with the ignition turned on, otherwise the electrical system or elec-
trical components will be damaged.
•
Do not expose the battery to direct sunlight over a long period of
time, as the intense ultraviolet radiation can affect the battery
housing.
•
If the car is left standing for long periods, protect the battery
from extreme cold temperature so that it does not “freeze up” and
become damaged.
Charging the battery
Terminals for charging the battery are fitted in the engine
compartment.– Note the warnings ⇒ in “Important safety warnings
for handling a car battery” on page 264 and ⇒.
– Switch off all electrical equipment. Remove the ignition
key.
– Open the bonnet ⇒page 254.
– Open the red cap on the positive terminal ⇒fig. 259.
– Follow the correct procedure for connecting the charger
cables to the jump-start terminals (terminal with red cap
= “positive”, terminal with hexagon = “negative”).
WARNING (continued)
Fig. 259 Engine
compartment: Termi-
nals for jump leads and
battery charger
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Checking and topping up fluids267
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
Windscreen washerPlain water on its own is not sufficient for the windscreen
washer system.The container for the windscreen washer
 contains the cleaning
fluid for the windscreen and the headlight washer system*
⇒fig. 260. Container capacity: ⇒page 321.
Plain water on its own is not enough to clean the glass properly. It
is therefore advisable to add a suitable washer fluid additive (with
wax solvent) to the water. A washer fluid with freeze-resistant addi-
tive should be used in winter.
Caution
•
Never put in radiator anti-freeze or other additives.
•
Never use washer fluid which contains paint thinners or solvents
as it can damage the paintwork.
Fig. 260 Engine
compartment: Wind-
screen washer
container
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Fuses and bulbs305
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
WARNING
•
Take particular care when working on components in the
engine compartment if the engine is warm - risk of burns!
•
Bulbs are sensitive to pressure. The glass can break when you
touch the bulb, causing injury.
•
Incorrect handling of the high-voltage element of xenon gas-
discharge bulbs* can have potentially fatal consequences.
•
When changing bulbs, please take care not to injure yourself on
sharp edges, in particular on the headlight housing.Caution
•
Always remove the ignition key before carrying out any work on
the electrical system - danger of short circuiting!
•
Switch off the lights or parking lights before you change a bulb.
•
Take good care to avoid damaging any components.
•
Removing the lights in particular can lead to the paintwork
becoming damaged. This is another reason why we recommend
having the bulbs changed by a qualified workshop.For the sake of the environment
Please ask your specialist retailer how to dispose of used bulbs in
the proper manner.
Note
Place the parts you have removed on a soft cloth so that they do not
become scratched.•
Please check at regular intervals that all lighting (especially the
exterior lighting) on your vehicle is functioning properly. This is not
only in the interest of your own safety, but also in that of all other
road users.
•
Before changing a bulb, make sure you have the correct new
bulb.
•
Do not touch the glass part of the bulb with your bare hands, use
a cloth or paper towel instead. Otherwise, the fingerprints left on
the glass will vaporise as a result of the heat generated by the bulb,
be deposited on the reflector and impair its surface.
Bulbs with a bayonet fastenerBulbs with a bayonet fastener must be changed as follows:
Removing the bulb
– Lightly press the defective bulb into the bulb holder, then
turn it anti-clockwise and remove it.
– Do not touch the glass part of the new bulb with your
bare hands, use a cloth or paper towel instead.
Fitting the bulb
– Fit the new bulb, pressing it into the bulb holder, and turn
it clockwise as far as it will go.
– If necessary, use a cloth to remove any fingerprints from
the glass part of the bulb.
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Index 330AAbroad
Changing headlight dip settings . . . . . 59
ABS
SeeAnti-lock brake system . . . . . . . . . 19
AC mode . . . . . . . . . . . . . . . . . . . . . . . 98, 107
Acceleration figures
SeePerformance, weights and
dimensions . . . . . . . . . . . . . . . . . . . . 323
Accessories . . . . . . . . . . . . . . . . . . . . . . . . 277
Trailer . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Acoustic parking aid . . . . . . . . . . . . . . . . 169
Adapter for anti-theft wheel bolts . . . . . 292
adaptive cruise control . . . . . . . . . . . . . . 128
Driver intervention prompt . . . . 130, 138
Driver messages . . . . . . . . . . . . . . . . . 134
Driving program . . . . . . . . . . . . . . . . . 139
Error messages . . . . . . . . . . . . . . . . . . 136
Indicator lamps . . . . . . . . . . . . . . . . . . 134
No vehicle in front . . . . . . . . . . . . . . . 130
Overriding . . . . . . . . . . . . . . . . . . . . . . 130
Setting a new speed . . . . . . . . . . . . . . 131
Setting distance . . . . . . . . . . . . . . . . . 133
Setting speed . . . . . . . . . . . . . . . . . . . 131
Setting time interval . . . . . . . . . . . . . . 133
Settings . . . . . . . . . . . . . . . . . . . . . . . . 139
Status messages . . . . . . . . . . . . . . . . . 136
Switching off (with memory function) . . .
131, 132
Switching on and off . . . . . . . . . . . . . 131
System limitations . . . . . . . . . . . . . . . 140
Vehicle in front . . . . . . . . . . . . . . . . . . 130Vehicles with manual gearbox . . . . . . 129
Volume of warning tone . . . . . . . . . . . 139
adaptive light . . . . . . . . . . . . . . . . . . . . . . . 61
Defective . . . . . . . . . . . . . . . . . . . . . . . . 39
advanced key
Locking and unlocking the vehicle . . . 47
START ENGINE STOP button . . . . . . . 118
Starting the engine . . . . . . . . . . . . . . . 118
Switching on the ignition . . . . . . . . . . 118
Air conditioner . . . . . . . . . . . . . . . . . . 93, 101
AC mode . . . . . . . . . . . . . . . . . . . . . . . . . 98
See alsoDeluxe automatic air conditioner
93
Air recirculation mode
Deluxe automatic air conditioner . . . . 97
Deluxe automatic air conditioner plus . . .
105
Airbag . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Deactivating . . . . . . . . . . . . . . . . . . . . . 208
Front airbags . . . . . . . . . . . . . . . . . . . . 203
Head-protection airbag . . . . . . . . . . . 207
Key-operated switch for front passenger's
airbag . . . . . . . . . . . . . . . . . . . . . . . . . 208
Side airbags . . . . . . . . . . . . . . . . . . . . . 205
Triggering . . . . . . . . . . . . . . . . . . . . . . 202
Warning lamp . . . . . . . . . . . . . . . . . . . . 17
Alarm system
SeeAnti-theft alarm system . . . . . . . . . 42
Alterations to the vehicle . . . . . . . . . . . . . 277
Alternator
Fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Anti-dazzle interior mirror . . . . . . . . . . . . . 69
Anti-freeze additive . . . . . . . . . . . . . . . . . 260Anti-knock properties of petrol . . . . . . . . 251
Anti-lock brake system
How the system works . . . . . . . . . . . . 222
Warning lamp . . . . . . . . . . . . . . . . . . . . 19
Anti-theft alarm system . . . . . . . . . . . . . . . 42
Interior monitor . . . . . . . . . . . . . . . . . . . 50
Tow-away protection . . . . . . . . . . . . . . 50
Anti-theft wheel bolts . . . . . . . . . . . . . . . . 292
Armrest (front)
Adjusting . . . . . . . . . . . . . . . . . . . . . . . . 78
Storage compartment . . . . . . . . . . . . . . 78
Ashtrays
Front . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Audi braking guard . . . . . . . . . . . . . . . . . . 142
Error messages . . . . . . . . . . . . . . . . . . 143
Settings . . . . . . . . . . . . . . . . . . . . . . . . 144
Status messages . . . . . . . . . . . . . . . . . 143
Switching on and off . . . . . . . . . . . . . . 144
Audi drive select . . . . . . . . . . . . . . . . . . . . 159
Dynamic steering . . . . . . . . . . . . . . . . 159
Suspension control . . . . . . . . . . . . . . . 159
Audi hold assist . . . . . . . . . . . . . . . . . . . . 124
Warning lamp . . . . . . . . . . . . . . . . . . . . 19
Audi lane assist
Seelane assist . . . . . . . . . . . . . . . . . . . 145
Audi parking system . . . . . . . . . . . . . . . . . 169
Audi parking system advanced . . . . . . . . 171
Audi parking system plus . . . . . . . . . . . . 170
Auto Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Auto-check control . . . . . . . . . . . . . . . . . . . 30
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