wheel AUDI S4 CABRIOLET 2009 Owner's Guide

-Airbag system --=----=----------------
& W
ARNING (continued )
• Improper installation of child restraints can reduce their effec­
tiveness or even prevent them from p roviding any protection .
• An improperly installed child restraint can interfere with the
airbag as it deploys and seriously injure or even kill the child -
even with an Advanced Airbag System .
• Always carefully follow the manufa cturer's instru ctions
provided with the child safety seat or carrier .
• Never place additional items on the seat that can increase the
total weight registered by the weight-sensing mat and can cause injury in a crash .
LJ
Front airbags
Description of front airbags
The air bag sy stem can provi de su ppleme ntal pr ote ct io n
to prope rly r estrai ned fron t se at occu pants.
Fig. 1 7 1 L ocation of
driver airbag: in
s teeri ng w heel
Fig . 172 Location of
fron t pa ssenger' s
airbag : in the in stru ­
ment panel
Your vehicle is equipp ed with an " Advanced Airbag System" in
complia nce wit h United States Federal Motor Vehicle Safe ty Stan ­
dard (FMVSS) 208 as appl icab le at the time your veh icle was manu ­
f act ured. The safety bel ts for the front seat s have "pretensi one rs"
t ha t help to take slack ou t of the be lt s ystem. The p re tens io ne rs a re
also activated by the electronic control unit for the airbag system.
The fr ont safe ty belts als o h ave loa d lim iters to hel p reduce the
forces applied to the body in a crash.
The a irbag f or the driver is i n the st eeri ng wheel hub~ fig. 171 a nd
t h e airbag for the front passenger is in the i nstrument panel
~ fig. 172. The genera l location of the airbags is marked "AIRBAG".
There is a lot you need to know ab out t he airbags in y our vehicle. We
u rge you to read the deta iled information about airbags, safety belts
and child s afety i n th is and th e other c ha pt ers t hat make u p the
owner's literature. Please be sure to heed the WARN INGS -they are
e xt reme ly im portan t for y our safe ty a nd the safe ty of y our passen ­
gers, especia lly infants and small childr en.
& WARNING
Never rely on airbags alone for protection .
• Even when they deploy, airbags provide only supplemental
protect ion .

Airbag system -----------------=~-
& WARNING (continued)
• If you must install a rearward facing child safety seat on the
front passenger seat because of exceptional circumstances and
the PASSENGER AIR BAG OFF light does not come on and stay on,
immediately install the rear -facing child safety seat in a rear
seating position and have the airbag system inspected by your
Audi dealer.
_& WARNING
If, in exceptional circumstances, you must install a forward-facing
child restraint on the front passenger's seat:
• Always make sure the forward-facing seat has been designed
and certified by its manufacturer for use on a front seat with a
passenger front and side airbag .
• Never put the forward-facing child restraint up against or very
near the instrument panel.
• Always move the passenger seat into its rearmost position in
the seat's fore and aft adjustment range, as far away from the
airbag as possible, before installing the forward-facing child
restraint. The backrest must be adjusted to an upright position.
• Make sure that the PASSENGER AIR BAG OFF light comes on
and stays on all the time whenever the ignition is switched on. •
Advanced Airbag System components
The front passenger seat in your vehicle has a lot of very important
parts of the Advanced Airbag System in it. These parts include the
weight-sensing mat, sensors, wiring, brackets, and more. The func­
tion of the system in the front passenger seat is checked by the elec­
tronic control unit when the ignition is on. The control unit monitors
the Advanced Airbag System and turns the airbag indicator light on
when a malfunction in the system components is detected. The
function of the airbag indicator light is described in greater detail
Controls and equip­ ment Safety first Vehicle operation
below.
Because the front passenger seat contains important parts
of the Advanced Airbag System, you must take care to prevent it
from being damaged. Damage to the seat may prevent the
Advanced Airbag for the front passenger seat from doing its job in
a crash.
The front Advanced Airbag System consists of the
following:
• Crash sensors in the front of the vehicle that measure vehicle
acceleration/deceleration to provide information to the Advanced
Airbag System about the severity of the crash.
• An electronic control unit, with integrated crash sensors for front
and side impacts. The control unit "decides" whether to fire the
front airbags based on the information received from the crash sensors. The control unit also "decides" whether the safety belt
pretensioners should be activated.
• An Advanced Airbag with gas generator for the driver inside the
steering wheel hub.
• An Advanced Airbag with gas generator inside the instrument
panel for the front passenger .
• A weight-sensing mat under the upholstery padding of the front
passenger seat cushion that measures the total weight on the seat.
The information registered is sent continuously to the electronic
control unit to regulate deployment of the front Advanced Airbag on
the passenger side.
• An airbag monitoring system and indicator light in the instru ­
ment cluster ~
page 179.
• The PASSENGER AIR BAG OFF light comes on and stays on in the
center of the instrument panel~
page 180, fig. 174 and tells you
when the front Advanced Airbag on the passenger side has been
turned off .
• A sensor below the safety belt latch for the front seat passenger
to measure the tension on the safety belt. The tension on the safety
belt and the weight registered by the weight -sensing mat help the
control unit "decide" whether the front airbag for the front _,.
Vehicle care Do-it-yourself service Technical data

__ __::_A:::..:..:. ir..::b ~ a::. g::!...: s:::L y..::s :.::t :.::e :.:.m.:..:.... ________________________________________________ _
or the lower parts of t he body. Front airbags on ly supp lement the
th ree p oint safe ty belts in s ome front al c olli sio ns in which the
vehic le dece leration is high enou gh to deploy th e airbags .
Front airbags will not deploy:
• if the ignition is switched off when a crash occ urs,
• i n sid e coll is ions ,
• i n rea r- e nd collisi ons ,
• in rollovers,
• when th e c ras h de cele rat io n measu red by th e airba g sys tem is
l ess than the minimum threshold needed for a irbag deplo yment as
r egi stere d by t he ele ctr onic con trol unit.
The front passenger airbag will also not deploy :
• whe n t he fr ont pass enge r sea t is not occup ied,
• when the weight on the front passenger seat as sensed by the
A dvanced A ir b ag Sys te m in d ica tes th at the fr ont airba g on the
p assenge r side has to be t urned off b y the e lectronic cont rol unit
(t he
PASSENGER AIR BAG OFF ligh t com es o n an d stays o nl.
& WARNING
Sitting in the wrong posit ion can increase the risk of serious injury
in crashes .
• To reduce the risk of injury when the airbags inflate , the driver
and passengers must always sit in an upright position , must not
lean against or place any part of the ir body too close to the area
where the airbags are located.
• Occupants who are unbelted , out of posit ion or too close to the
airbag can be seriously injured by an airbag as it unfolds with
great force in the blink of an eye:::::,
page 170 .
& WARNING
A child in a rearward-facing child safety seat installed on the front
passenger seat will be seriously injured and can be killed if the
front airbag inflates - even with an Advanced Airbag System .
• The inflating airbag will hit the child safety seat or infant
carrier with great force and will smash the child safety seat and
child against the backrest , center arm rest , door or roof.
• Always install rear-facing child safety seats on the rear se at.
• If you must install a rearward facing child safety seat on the
front passenger seat because of exceptional circumstances and
the PASSENGER AIR BAG OFF light does not come on and stay on, i mmediately install the rear-facing child safety seat in a rear
seating position and have the airbag system inspected by your
Audi dealer .
& WARNING
Objects between you and the airbag will increase the risk of injury
in a crash by interfering with the way the airbag unfolds or by
being pushed into you as the airbag inflates .
• Never hold things in your hands or on your lap when the vehicle
is in use.
• Never transport items on or in the area of the front passenger
seat. Objects could move into the area of the front airbags during
braking or other sudden maneuver and become dangerous projec ­
tiles that can cause serious personal injury if the airbags inflate .
• Never place or attach accessories or other objects (such as cup
holders , telephone brackets , large, heavy or bulky obje cts) on the
doors , over or near the area marked "AIRBAG" on the steering
wheel, instrument panel , seat backrests or between those areas
and yourself . These objects could cause injury in a crash, espe­
cially when the airbags inflate .
• Never recline the front passenger's seat to transport objects .
Items can also move into the area of the side airbag or the front ..,

___ A_ ir_b _ a_ g~ s_ y_s _t _e _m _________________________________________________ _
& WARN IN G (c ontinu ed )
seating posit ion and ha ve the airb ag system inspected by your
Audi dealer .
• A t ight tether or other strap on a rearward-fa cing child restr aint
atta ched to the front pas senger se at can put too much pres sure
on the weight-sensing mat in the seat and reg ister more weight
than i s actually on the seat. The heavier weight registered can
make the system work as though an adult were on the seat and
deploy the Advanced Airbag when it must be suppre ssed causing
serious or even fatal injury to the child .
• If, in exc eptional cir cum stance s, you mu st in stall a forward ­
facing child restraint on the front passenger seat , always move the
seat into its rearmost po sition in the seat's fore and aft adjust ­
ment range , as far away from the airbag as possible . The ba ckrest
must be adjusted to an upright position. Make sure that the
PASSENGER AIR BAG OFF light comes on and stays on all the time
whenever the ignition is switched on .
& WARNING
• If the PASSENGER AIR BAG OFF light does not go out when an
adult is sitting on the front passenger seat after taking the steps
described above, make sure the adult i s properly seated and
restrained at one of the rear seating position s.
• Have the airbag system inspected by your Audi dealer before
transpo rting anyone on the front passenger seat .
[ i ] Tips
If the weight -sensing mat in the front passenger seat detects an
e m pty seat , the fron t airbag on the passenge r side will be tu rned
off, and PASSENGER AIR BAG OFF will stay on.•
Repair, care and disposal of the airbags
P arts of the airbag system are installed at many different p laces on
your Au di. Insta lli ng, removing, se rvic ing or repa iring a par t in an
area of the vehicle can damage a part of an airbag system and
p revent that system from w orking properly in a c ollisi on.
There are some important things you have to know to make sure
that the effectiveness of the system will not be impai red and that
discarded componen ts do no t cause injury or po llute t he e nv iro n­
ment .
& WARNING
Improper care , servicing and repair procedures can increase the
risk of personal injury and death by preventing an airbag from
deploying when needed or deploying an airbag unexpectedly:
• Never cover , obstruct , or change the steering wheel horn pad
or airbag cover or the instrument panel or modify them in any way .
• Never attach any objects su ch as cup holders or telephone
mountings to the surfa ces covering the airbag units .
• For cleaning the horn pad or instrument panel , use only a soft ,
dry cloth or one moistened with plain water. Solvents or cleaner s
c ould damage the airbag cover or change the st iffness or strength
of the material so that the airbag cannot deploy and protect prop­
erly .
• Never repair , adju st, or change any parts of the airbag sy stem .
• All work on the steering wheel , instrument panel, front seats or
electrical system (including the installation of audio equipment ,
cellular telephones and CB rad ios , etc .I must be performed by a
qualified technician who has the training and special equipment
necessary .
• For any work on the airbag system, we strongly recommend
that you see your author ized Audi dealer or qualified workshop .
• Never modify the front bumper or parts of the vehicle body .

___ A_ ir_b _a_ g:-- s-=- y_s _t _e _m _________________________________________________ _
& WARNING
Item s s to red betwe en th e safe ty belt b uckle a nd th e cente r
co nso le can c au se the sen sors in the buc kle to send the wro ng
inf orm ation t o the e lec tronic c ontrol m odule and pre vent th e
Adv anced Airb ag System fr om working pr operly .
• Always make su re that n oth ing ca n int erfere with the saf ety
belt buckle s and that they ar e not ob structed.
<£> For the sake of the environment
Undeployed airbag modules and pretensioners might be c lassified
as Perchlorate Material -specia l handling may apply, see
www .dtsc.ca .gov/hazardouswaste/perchlorate. When the vehicle o r
parts of the restraint system including airbag modules safety be lts
with pretensioners are scrapped, all applicable laws and regula ­
tions must be observed . Your author ized Audi dealer is fami liar with
these requirements and we recommend that you have your dea ler
perform th is service for you. •
Knee airbags
Description of knee airbags
The airbag system can pr ovide supplemental protection
t o properly restrained fron t se at occu pants.
Fi g. 175 Dr iver's
ai rba g
The airbag for the driver is located in the instrument panel under ­
neath the steering wheel=> fig. 175, the airbag for the passenger is
at about the same height in the instrument panel underneath the
g love compartment.
The knee airbag offers additional protection to the driver 's and
passenger's knees and upper and lower thigh areas as a supple­
ment to the safety be lts.
If the front airbags deploy, the knee airbags also deploy in frontal
coll isions above a certain severity=>
page 177, "More important
things to know about front airbags".
Besides their normal safety function, safety be lts work to help keep
the driver or front passenger in position in case of a frontal collision
so that the airbags can provide protection.
The airbag system is not a substitute for your safety belt. Rather, it is part of the overall occupant restraint system in your vehicle.
Always remember that the airbag system can only help to protect
you if you are wearing your safety belt and wearing it properly. This
~

-Airbag system ----=--=---------------------------------
If the front airbags d ep loy, the kne e airbags a lso d ep loy in frontal
c oll is ions abov e a certai n s ev er ity.
Whe n the syst em is dep loy ed, the airba gs start to f ill with a prope l­
l ant gas, and inf late bet ween t he lower pa rt of the instr ument pa ne l
and the drive r and the l ower part of th e instru ment pane l a nd th e
front passenge r:::;, page
177 , fig. 173 .
A lth oug h the y are no t a s oft p illow, t hey can "cushion" th e im pact
and in this way they can help to r educe the ris k of injury to the lower
e xt remitie s.
A ll thi s takes place ins ta nta ne ous ly, so fast tha t many p eople don't
even realize that the airbags have deployed. The ai rbags a lso inf late
w it h a gre at d eal o f f orce and it is im por tant for occupa nt safety t hat
nothing sho uld be in their way when they dep loy.
Full y infla ted ai rbags i n co mbina tion wi th properl y w orn safe ty bel ts
s low down and limit the occupant's forward movement and he lp to
r e du ce t he risk .•
Important safety instructions on the knee
airbag system
Air bag s are only sup plemen tal restra ints. Alwa ys wea r
s af ety bel ts co rr e ctly and ride i n a prop er se atin g po sition .
Ther e is a lo t that you and your passe ngers must know a nd do to
he lp the safety belts and airbags to provide supp lemental protec ­
ti on .
& WARNING
An inflating knee airbag can cause serious injury. Wearing safety
belts incorrectly and improper seating positions increase the risk
of serious personal injury and death whenever a vehicle is being
used .
• The airbag system cannot protect you properly if you are
seated too close to any of the airbag locations . When adjusting
& WARNING (continued )
their seat positions, it is important that both the driver and the
front passenger keep their upper bodies and knees at the
following minimum safe d istances :
-1 O inches (25 cm) between the chest and the steering
wheel /instrument panel .
- 4 inches (10 cm) between the knees and the lower part of the
instrument panel.
• The risk of personal injury increases if you lean forward or to
the side, or if the seat is improperly positioned and you are not
wearing your safety belt. The r isk increases even more should the
airbag deploy .
• Always make sure that the knee airbag can inflate without
interference. Objects between yourself and the airbag can
increase the risk of injury in an accident by interfering with the
way the airbag deploys or by being pushed into you as the airbag
deploys.
-No persons (children) or animals should ride in the footwell
in front of the passenger seat . If the airbag deploys, this can
result in serious or fatal injuries.
- No objects of any kind should be carried in the footwell area
in front of the driver's or passenger's seat. Bulky objects (shop­
ping bags , for example) can hamper or prevent proper deploy ­
ment of the airbag . Small objects can be thrown through the
vehicle if the airbag deploys and injure you or your passengers .
• Make sure there are no cracks , deep scratches or other damage
in the area of the instrument panel where the knee airbags are
located .
• If children are incorrectly seated , their risk of injury increases in
the case of an accident:::;,
page 190, "Child Safety". •

The direction in which the driver wishes to travel is determined with
the aid of the steering angle and vehicle speed and is continua lly
compared with the actual behavior of the vehicle. If the two do not
match, -for example, when the vehicle starts hydrop laning on a
wet road -, ESP will automatical ly brake the appropriate wheel to
correct the problem.
The veh icle is then stabi lized by the forces act ing on the whee l
during braking. If the vehicle is oversteering (rear tends to skid out
of the turn), the brakes are mainly app lied on the whee l that is on
the outside of the curve. In the case of a vehicle that is understeering
(tendency to s lide out of the curve), the brakes are applied at the
rear wheel that is on the inside of the curve . An acoustic signal indi­
cates when ESP brake application cuts in =>
&.
The system operates across the entire speed range in combinat ion
with the ABS system => page 216 . If the Anti -Lock Brake System
(ABS) malfunctions, the ESP wi ll be out of act ion as well.
Activa tion
When you turn on the engine, ESP w ill automatica lly be activated
and will perform a self -test .
The system can be activated o r deactivated by pressing the butto n
=> page 212, fig . 190 . The warning light comes on when the system
is switched off .
Normally, the ESP should a lways be on, however, it may be advanta­
geous to turn off the system in certain specia l cases when some
degree o f wheel spin is desired such as :
• when driving with snow chains
• when driving in deep snow or on a loose surface (to allow the
whee ls to dig in to reach firm ground)
• when trying to "rock" the vehicle free whe n it has become stuck .
The system shou ld be reactivated once you are no longer in such
situations.
Both , the ABS and EDL systems are still functioning even if the ESP
is switched off .
Controls and equip­
ment Safety first Vehicle operation
Int
ellig ent tec hnol ogy
& WARNING
The Ele ctron ic Stab ilization Program is neve rth ele ss s ubje ct to th e
law s of phy sic s. It is p art icularly important to pay at tent ion to thi s
f ac t on wet and slipper y ro ad s. It i s therefore important th at yo u
alway s adapt your driving to the condition of the road and traffic
c onditio ns. Do not allo w the in crea sed safety prov ided by t he Ele c­
tronic Stabilization Program sy stem to lull you into a ccepting
addition al safety ri sk s.
• Plea se note that when ESP i s deactivated , the drive wheel s can
s pin on icy and slippery ro ads a nd the vehi cle can break away -
d anger of skidding ! C
E lectronic differential lock CEDL)
The electronic differential lock monitors the rotational
speed of the drive wheels.
Gener al notes
The electronic differential lock (EDU helps the car to start moving,
accelerate and c limb a gradien t on surfaces providing poor or
a lmost no grip . Without EDL, this would be difficult , if not impos ­
sible.
How the syst em works
The EDL operates automat ical ly . It monito rs the rotationa l speed of
the drive whee ls on an axle with the he lp of the ABS sensors
=> page 216 . If a noticeable difference in rotational speed between
the drive wheels on one axle is de tected (e.g. on slippery grou nd on
one side), the spinning wheel is braked, thereby transferring power
to the other drive wheel or wheels (a ll -whee l drive) . This is done up
to a speed of about 60 mph ( 100 km/h). Noises from the brake
system signal that wheel spin is being control led.
~
Vehicle care Do-it-yourself service Technical data

___ ln_ te_ ll..,,ig ..,_ e_ n_t _t_ e_ c_ h _ n_o _ l_o _,.g= y,_ __________________________________________ _
Driving off
When driving off, always be sure to keep road conditions in mind as
you accelerate. If one drive wheel spins because it is on a surface
with less grip, gradually increase the pressure on the accelerator
pedal until the car starts to move. The wheel less able to transfer
power spins.
Overheating of brakes
To prevent the disc brake of the braked wheel from overheating if
subjected to excessive loads, the EDL cuts out temporarily. The
vehicle remains operational and behaves in the same way as a
vehicle without EDL.
As soon as the brake has cooled down, EDL switches on again auto­ matically.
& WARNING
• When accelerating on slippery surfaces, such as on ice or snow,
always be careful when depressing the accelerator pedal. Even
with the EDL working, the drive wheels can spin and reduce your ability to control your car. -Risk of crash!
• The increased safety afforded by EDL does not mean that you
can take safety risks. Always adapt your driving style to the road
conditions and traffic situation.
[ i] Tips
If a fault occurs in the ABS, the EDL is also not functioning. This is
indicated by the ABS warning light=>
page 20. •
Anti-Slip Regulation System (ASR)
The Anti-Slip Regulation System prevents the driven
wheels from spinning when the car is accelerating.
General notes
The Anti-Slip Regulation System (ASR) is integrated in the electronic
stabilization program (ESP). When the vehicle starts up and acceler­
ates, the wheels are prevented from spinning by adjusting the
engine power to match the amount of grip available from the road
surface.
How the system works
ASR performs automatically, i.e. without the driver's intervention.
With the aid of the ABS sensors=>
page 276, ASR monitors the
speed of the driven wheels. If the wheels start to spin, the engine
power is reduced automatically until the tires find enough grip to
lock onto the road surface. The system is active across the entire
speed range.
Th e ASR works in conjunction with the ABS. If a malfunction should
occur in the ABS, the ASR will also be out of action.
& WARNING
The increased safety afforded by ASR does not mean that you can
take safety risks. Always adapt your driving style to the road
conditions and traffic situation.
[ i] Tips
To ensure that the ASR works properly, all four wheels must be fitted
with identical tires Any differences in rolling radius of the tires can
cause the system to reduce engine power when this is not desired.
S ee also =>
page 279, "New tires and replacing tires and wheels". •

Braking
General information
What affects braking efficiency?
O pera tin g co ndition s and drivi ng h abit s
The brakes on today's automobiles are still subject to wear,
depending large ly on operating conditions and dr iving habits~
&­
On vehicles that are either driven mostly in stop -and -go city traffic
or are driven hard, the brake pads shou ld be checked by your autho­
rized Audi dealer more often than specified in the
W arr anty & Main ­
t e nanc e bo okle t.
Fai lure to have you r brake pads inspec ted ca n
resu lt in reduced brake performance.
On steep slopes, you shou ld use the braking effect of the engine.
This way, you prevent unnecessary wear on the brake system. If you must use your brakes, do not hold the brakes down continuous ly.
Pump the brakes at intervals.
Moi sture or road salt
If you are driv ing faster than 50 mph (80 km/h) and the windshie ld
wipers are on, the brake pads wi ll briefly touch the brake discs in
regu lar intervals so as to improve reaction time when braking on
wet surfaces. You, the driver, wil l not notice anything.
Under ce rta in conditions, for example, when dr iving through water
or very heavy rain, or even after washing your vehicle, the braking
effect can be reduced due to moisture (or in freezing conditions ice)
on the brake pads. A few cautious brake applications should dry off
the b rake pads or remove any ice coatings .
At speeds
over80 km/h and with the windshie ld wiper turned on, the
brake pads are app lied briefly to the brake discs. This occurs at
regu lar interva ls wi thout the driver not icing and provides for better
brake response time under wet conditions.
The effectiveness of the brakes can be reduced when the vehicle is driven on a sa lt-covered road and the brakes are not used. Likewise,
Controls and equip­
ment Safety first Vehicle operation
Int
ellig ent tec hnol ogy
you clean off accumulated sa lt coating from brake discs and pads
with a few ca utious applications of the brake ~
&-
Cor rosi on
There may be a tendency for dirt to build up on the brake pads and
corrosion to form on the discs if the car is not driven regularly or
only f or sho rt trips with little use of the brakes.
If the brakes are not used frequently, or if corrosion has formed on
the discs, it is advisable to clean off the pads and discs by braking
firm ly a few times from a moderately high speed~
&-
Fa ults in the brake system
If you shou ld notice a sudden increase in brake pedal trave l, then
one of the two brake circuits may have failed~
&-
Lo w brak e fluid l evel
Malfunctions can occur in the brake system i f the brake fluid level is
too low . The brake fluid level is monitored electronically .
Brake lining wear statu s
Brake lining wear may be checked by visua l inspection of the condi ­
tion o f the brake pads through the open ings in the wheel. If neces­
sary, the wheel may be removed for this inspection
~ page 293,
"Whee l change".
& WARNING
• You should perform braking maneuver s for the purpo se of
cl eani ng th e br ake sy stem onl y if ro ad condition s permit . Other
road u se rs mu st not be put a t ris k -you may cau se an accident!
• Before des cending a steep gr ade , reduce sp eed and sh ift tr ans ­
mi ssion into a lower gear or lower driving po sition . Do not ride the
brake s or hold the pedal d ow n too long or t oo often . This could
cau se the brake s to get hot and dimini sh brakin g efficien cy . _.
Vehicle care Do-it-yourself service Technical data

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& WARNING (continued)
• Do not "ride the brakes" by resting your foot on the pedal when
you do not intend to brake. This may cause the brakes to overheat, premature wear and increased stopping distance.
• Under certain climatic and operating conditions such as
passing through water, driving in heavy rain or after washing the
vehicle, the effectiveness of the brakes can be reduced. In winter,
ice can accumulate on the brake pads, linings, discs and drums .
Cautiously apply brakes for a test. Brakes will dry and ice coatings
will be cleaned off after a few cautious brake applications .
• Driving for an extended period of time on salt-covered roads
without using your brakes can also affect braking efficiency. Clean
off accumulated salt coating from brake discs and pads with a few
cautious brake applications.
• If you damage the front spoiler, or if you install a different
spoiler, be sure the air flow to the front brakes is not obstructed.
Otherwise the brake system could overheat reducing the effective ­
ness of the entire brake system.
• Failure of one brake circuit will impair the braking capability
resulting in an increased stopping distance. Avoid driving the
vehicle and have it towed to the nearest Audi dealer or qualified
workshop. u
Brake booster
The brake booster adds extra braking power.
The brake booster works with vacuum pressure which is created
only when the engine is running~ &.
& WARNING
• Never let the vehicle roll to a stop with the engine shut off.
• If the brake booster is not working, for example when towing
your vehicle, or because the brake booster has somehow been
& WARNING (continued)
damaged, the brake pedal must be pressed considerably harder to
make up for the lack of booster assistance. •
Functioning of Anti-Lock Brake System (ABS)
ABS prevents the wheels from locking up under braking.
The ABS contributes effectively to vehicle control since it prevents
the wheels from
locking when the brakes are applied. This means
that the vehicle remains steerable and is less likely to skid.
With ABS you do not need to pump the brake. Just hold the brake
pedal down.
However , do not expect that the ABS shortens braking distance
under
all circumstances. When driving on gravel or on newly fallen
snow on top of icy surfaces, braking distance may be even longer,
therefore, under these circumstances, it is especially important that
you drive slowly and with great care.
How the ABS system works
An automatic check is made when a speed of about 4 mph (6 km/h)
is reached. When this happens, a pumping noise can be heard.
If an individual wheel begins to rotate too slowly in relation to
vehicle speed and tends to lock, the ABS automatically reduces brake pressure to prevent that wheel from locking.
This automatic adjustment process will cause a
slight vibration of
the brake pedal and some noises to alert you that vehicle speed
must be adapted to existing road and traffic conditions.
& WARNING
Although the ABS is very effective, always remember that braking
capability is limited by tire traction . Always adjust your driving
speed according to the road and traffic conditions. Do not let the .,_