2009 AUDI A4 CABRIOLET sensor

Side airbags
Description of side airbags
The airbag system can provide supplemental protecti on
to pro perly restrained fr ont seat occupants.
Fi g. 177 Si de air bag
l oca tio n in th e driv er's
sea t
The s ide airbags are located in the sides of the front seat backrests
=> fig. 177 facing the doors. They are identified by the word
" AIRBAG" .
The side airba g sy stem b asica lly con sis ts of :
• the electronic contro l module and external side impact sensors
• the two s ide airbags located in th e sides of the front backrests
• the airbag warning light in the instrument cluster .
Th e airbag system is monitored elec tronically to make certain that
it is function ing properly at all times . Each time you turn on the igni ­
tion , the airbag system indicator light will come on for a few
seconds (self diagnostics).
The side airbag system supplements the safety belts and can help to reduce the risk of injury to the driver 's and front passenger 's
uppe r torso on the side of the vehicle that is struck in a side co lli­
sion . The airbag d eploys only in side impacts and on ly when the
vehicle acceleration registered by the contro l unit is high enough. If
this rate is below the reference value programmed into the contro l
Safety first
Airbag syst em
unit, the side airbags will not be triggered, even though the car may
be badly damaged as a result of the collision . It is not possible to
def ine an airbag trigger ing range that will cover every possible
ang le of impact, since the circumstances will vary considerably
between one collision and another . Important factors include , for
examp le, the nature (hard or soft) of the impacting object, the angle
of impact, vehicle speed, etc.=>
page 188, "Impo rtant safety
instructions on the side airbag system" .
Aside from their norma l safety function, safe ty bel ts work to help
keep the driver or front passenger in position in the event of a side
coll ision so that the side airbags can provide protec tion .
The airbag system is
not a subst itute for your safety belt . Rather , it
is part of the overall occupant restraint system in your vehicle.
Always remember that the side airbag system can on ly he lp to
protect you if you are wearing your safety belt and wearing it prop ­
erly. This is another reason why you should a lways wear your safety
belts, not just because th e law requires you to do so~
page 159 ,
"Genera l notes".
It is important to remember that while the supp lementa l side airbag
system is designed to reduce the likelihood of serious injuries, othe r
injuries , for example, swelling , bruising, and minor abras ions can
also be associated with deployed side airbags . Remember too, side
airbags will deploy only once and on ly in certain kinds of accidents
- your safety belts are a lways there to off er protection.
Vehic le damage , repair costs or even the lack of veh icle da mage are
not necessarily an indica tion of over -sensitive or failed airbag acti­
va tion. In some collision s, both front and side airbags may infla te .
Remember too, that airbags will deploy on ly once and only in
certain kinds of collisions -your safety belts are always there to
offer protection in those acc idents in which airbags are not
suppos ed to deploy or when they hav e already deployed .
The si de airbag system will not d eploy :
• when the ig nition is turned off
• in side collisions when the acceleration measured by the sensor
is too l ow ..
~ehicle care Technical data

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& WARNING (continued)
-Always sit in an upright position and never lean against the
area where the supplemental side airbag is located.
- Never let a child or anyone else rest their head against the
side trim panel in the area where the supplemental side airbag
inflates.
- Always make sure that safety belts are worn correctly,
- Do not let anyone sitting in the front seat put their hand or
any other parts of their body out of the window .
• Always make sure that the side airbag can inflate without inter ­
ference .
- Never install seat covers or replacement upholstery over the
front seat backs that have not been specifically approved by
Audi.
- Never use additional seat cushions that cover the areas
where the side airbags deploy.
- Damage to the original seat covers or to the seam in the area
of the side airbag module must always be repaired immedi­
ately by an authorized Audi dealer .
• Objects between you and the airbag can increase the risk of
injury in an accident by interfering with the way the airbag unfolds
or by being pushed into you as the airbag inflates .
- Never place or attach accessories or other objects (such as
cup holders, telephone brackets, or even large, bulky objects)
on the doors, over or near the area marked "AIRBAG" on the
seat backrests .
- Such objects and accessories can become dangerous projec­
tiles and cause injury when the supplemental side airbag
deploys.
- Never carry any objects or pets in the deployment space
between them and the airbags or allow children or other
passengers to travel in this position .
Controls and equip­ ment Safety first
Vehicle operation
& WARNING (continued)
• Always prevent the side airbags from being damaged by heavy
objects knocking against or hitting the sides of the seatbacks.
• The airbag system can only be triggered once. If the airbag has
been triggered, the system must be replaced by an authorized
Audi dealership.
• Damage (cracks, deep scratches etc.I to the original seat covers
or to the seam in the area of the side airbag module must always
be repaired immediately by an authorized Audi dealer .
• If children are seated improperly, their risk of injury increases
in the case of an accident~
page 190, "Child Safety".
• Never attempt to modify any components of the airbag system
in any way .
• In a side collision, side airbags will not function properly if
sensors cannot correctly measure increasing air pressure inside
the doors when air escapes through larger, unclosed openings in
the door panel.
- Never drive with interior door trim panels removed.
-Never drive when parts have been removed from the inside
door panel and the openings they leave have not been properly
closed.
- Never drive when loudspeakers in the doors have been
removed unless the speaker holes have been properly closed.
- Always make certain that openings are covered or filled if
additional speakers or other equipment is installed in the
inside door panels .
- Always have work on the doors done by an authorized Audi
dealer or qualified workshop . •
Vehicle care Do-it-yourself service Technical data

--------------------------------------------~C~ h~ il~d ~S~ a~f e~ t~ YL _III
& WA RNIN G (conti nu ed )
• Alway s install rear-facing child safety se ats on the rear seat.
• If you mu st in stall a rearw ard f acing chi ld safety seat on the
front pa ssenger seat in exc eptional cir cum stance s and the
PA SSENGER AIR BAG OFF light do es not come on and stay on,
im medi ate ly install the re ar-fa cing child safety s eat in a rear
s e ating po sit ion and h ave the airb ag sys tem inspe cted im medi ­
ately by your Audi de aler .
& WARNING
If, in exceptional circum stance s, you must in stall a forward -facing
c hild re st ra int on the fr ont p ass eng er' s s eat :
• Alway s make sure the forward -facing seat ha s been de signed
and cert ified by it s manufa cturer f or use on a front se at with a
p ass enger front and side airbag .
• Always follow the m anufacturer's instruct ions provided with
the child safety seat or carrier.
• Alway s m ove the pa ss e nger sea t into its rearm ost p osit ion in
the seat' s fo re and aft adju stment r ange , as far away from the
a irb ag as possib le before installing the child r estr aint . The b ack­
rest mu st be adju sted to an upr ight po sition.
• Alw ays ma ke sure th at the PAS SENGER AIR BAG OFF light
c ome s on and stay s on all the time whenever the ignition i s
s witched on . •
Advanced front airbag system and children
Your vehicle is equipped with an "Advanced Airbag System" in
compliance with United States Federal Motor Vehicle Sa fety Stan ­
dard (FMVSS) 208 as applicab le at the time your vehicle was manu ­
factured .
Controls and equip­
ment Safety first Vehicle operation
The Advanced Airbag system in your vehicle has been certified to
meet the " low -risk" requirements for 3 and 6 yea r- old child ren on
the passenger side and small adu lts on the driver side. The low risk
deployment c rite ria are intended to reduce the risk of injury th rough
interaction with the airbag that can occur, for example, by being too
close to the steering whee l and instrument panel when the airbag
in flates . In add ition, the system has been cert ified to comply with
the "suppression" requirements of the Safety Standard, to turn off
the front airbag for infants up to 12 months who are restrained on
the front passenger seat in child restraints that are listed in the
Standard.
Even though your vehic le is equipped with an Advanced Airbag
system, all ch ildren, especially those 12 years and younger, should
a lways ride in the back seat proper ly restrained for the ir age and
s ize . The a irbag on the passenger side makes the front seat a poten­
tially dangerous p lace for a chi ld to r ide. The front seat is not the
safest place for a chi ld in a forward -facing child safety seat. It can be
a very dangerous place for an infant or a larger chi ld in a rearward ­
facing seat. •
Advanced Airbags and the weight-sensing
mat in the front seat
The Advanced Airbag System in your vehicle detects the p resence
of an infant or chi ld in a chi ld restraint on the front passenger seat
using the weight -sensing mat in the seat cushion and the sensor
below the safety belt latch on the front passenger seat that
measures the tension on the safety belt .
The weight -sensing mat measures t otal weight of the ch ild and the
child safety seat and a chi ld blanket on the front passenger seat. The
weight on the front passenge r seat is related to the design of the
child restraint and its "footprint", the size and shape of the bottom
of the child restraint as it sits on the seat. The weight of a child
restraint and its "footprint" vary for different kinds of child .,
Vehicle care Do-it-yourself service Technical data

-Child Safety ____ .:....__ __________________________ _
restraints and for the different models of the same kind of child
restraint offered by child restraint manufacturers.
The weight ranges for the individual types, makes and models of child restraints that the NHTSA has specified in the Safety Standard
together with the weight ranges of typical infants and typical 1 year­
old child have been stored in the control unit of the Advanced
Airbag System. When a child restraint is being used on the front passenger seat with a typical 1 year-old child, the Advanced Airbag
System compares the weight measured by the weight sensing mat
with the information stored in the electronic control unit.
The electronic control unit also registers the tension on the front
passenger safety belt. The tension on the safety belt for the front
passenger seat will be different for an adult who is properly using
the safety belt as compared to the tension on the belt when it is used to attach a child restraint to the seat. The sensor below the
latch for the safety belt for the front seat passenger measures the
tension on the belt . The input from this sensor is then used with the
weight to "decide", whether there is a child restraint with a typical 1
year-old child on the front passenger seat and whether or not the airbag must be turned off.•
Child restraints and Advanced Airbags
Regardless of the child restraint that you use, make sure that it has
been certified to meet United States Federal Motor Vehicle Safety
Standards and has been certified by its manufacturer for use with
an airbag. Always be sure that the child restraint is properly
installed at one of the rear seating positions. If in exceptional
circumstances you must use it on the front passenger seat, carefully read all of the information on child safety and Advanced Airbags
and heed all of the applicable WARNINGS. Make certain that the
child restraint is correctly recognized by the weight -sensing mat
inside the front passenger seat, that the front passenger airbag is
turned off and that the airbag status is always correctly signaled by
the
PASSENGER AIR BAG OFF light. Many types and models of child restraints have been available over
the years, new models are introduced regularly incorporating new
and improved designs and older models are taken out of produc­
tion. Child restraints are not standardized. Child restraints of the
same type typically have different weights and sizes and different
'footprints,' the size and shape of the bottom of the child restraint
that sits on the seat, when they are installed on a vehicle seat. These
differences make it virtually impossible to certify compliance with
the requirements for advanced airbags with each and every child
restraint that has ever been sold in the past or will be sold over the
course of the useful life of your vehicle.
For this reason, the United States National Highway Traffic Safety
Administration has published a list of specific type, makes and
models of child restraints that must be used to certify compliance
of the Advanced Airbag System in your vehicle with the suppression
requirements of Federal Motor Vehicle Safety Standard 208. These
child restraints are:
A. Car beds, manufactured on or after September 1,
2004:
• Cosco Dream Ride 02-719
B. Rear facing child restraint systems, manufactured
on or after September 1, 2004:
(When the restraint system comes equipped with a removable base,
compliance has to be certified with or without the basel.
• Britax Handle with Care 191
• Century Assura 4553
• Century Smart Fit 4543
• Cosco Arriva 02727
• Evenflo Discovery Adjust Right 212
• Evenflo First Choice 204
• Graco Infant 8457

-In
te llig ent tec hnolo gy --=---=-=-------------
Intelligent technology
Notice about data recorded by
vehicle control modules
Your vehicle is not equipped with an Event Data Recorder (EDRl,
installed by some manufacturers for the express purpose of
capturing data for retrieval after an accident or crash event . EDR's
are sometimes called "crash recorders" .
Some state laws restrict the retrieva l or downloading of data stored
by EDR's that were insta lled in a vehicle for the express purpose of
retrieving data after an accident or crash event without the owner's
consent.
Although your vehicle is not equipped with an EDR, it is equipped
with a number of electronic control modules for various vehicle systems such as, for examp le, engine function, emission control, as
we ll as for the airbags and safety belts.
T hese electronic control modules also record vehic le-rela ted da ta
during norma l ve hicle operation for diagnost ic and repair purposes .
The recording capacity of the electronic control modules is limited
to data (no sound is recorded) and only a small amount of data is
actually recorded over a very limited period of time and stored when
a system fault or other condition is sensed by a control unit. Some
of the data then stored may relate to vehic le speed, d irection,
braking as we ll as restraint system use and performance in the
event of a crash or other condition . Stored data can only be read and
down loaded with special equipment. •
Electronic Stabilization Program (ESP)
General information
The ESP improves the vehicle s tability.
I
A F ig . 19 0 Cen ter
co nsol e w ith ESP
sw itch
ESP is designed to he lp you maintain vehic le control in situa tions
where the car approaches the limits of "grip", especially when acce lerating and cornering . ESP reduces the risk of skidding and
improves stability under all road conditions .
The syst em opera tes across the en tire speed range in combination
with the ABS system. If the Anti-Lock Brake System (ABS) malfunc ­
tions, the ESP wil l a lso shut down .
How th e sys te m work s
The Anti-Lock Brake System (ABS) , E lectronic Differential Lock (EDU
and the Anti -Sl ip Regu lation System (ASR) are integrated in the e lec­
tronic stabi li z ation program. In addition to the data provided by
these functions, the ESP control unit requires additional measure­ ment data provided by high performance sensors . T he rotational
speed of the vehic le about its ver tica l axis, t he late ral acce leration
acting on the vehic le, the brake pressure and the steering ang le are
a ll measured .

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

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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". •

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0 Note
• Before winter sets in, have the coolant checked to see if the
coolant additive in your vehicle is sufficient to meet the climate
conditions. This is especially important if you live in a region where
the winter is extremely cold . If necessary, increase the proportion of
coolant additive to 60% .
• When adding coolant additive to your cooling system,
remember:
-We recommend using only coolant additive G12+ + (check the
label) for your vehicle. This coolant additive is available at autho­
rized Audi dealers. Other types of antifreeze can significantly
reduce corrosion protection . The resulting corrosion can cause a
loss of coolant and serious engine damage.
• Do not add any type of radiator leak sealant to your vehicle's
engine coolant. Adding radiator repair fluid may adversely affect the
function and performance of your cooling system and could result
in damage not
covered by your New Vehicle Limited Warranty. •
Checking the engine coolant level
The engine coolant level can be checked with a quick
glance.
Fig . 202 Engine
compartment: Coolant
expansion tank
Before you check anything in the engine compartment,
always read and heed all WARNINGS~ & in "Working in
the engine compartment" on
page 250.
Turn off the ignition.
- Let the eng ine cool down.
Place a thick rag over the coolant expansion tank
~ fig. 202 and carefully twist the cap counter-clockwise
~& .
Read the engine coolant level in the open coolant expan­
sion tank~ fig. 202. With a cold engine, the coolant level
should be between the "min" and "max" markings. When
the engine is warm, the level may be slightly above the
"max" marking .
The location of the coolant expansion tank can be seen in the
engine compartment illustration=>
page 252.
To obtain an accurate reading , the engine must be switched off .
The expansion tank in your vehicle is equipped with an electric
coolant level sensor.
When the coolant l evel is too low, the warning light in the Auto ­
Check System :::::,
page 31 will blink until you add coolant and the
level has been restored to normal. Even though there is an electric
coolant level sensor, we still recommend you check the coolant level
from time to time .
Coolant loss
Coolant loss may indicate a leak in the cooling system. In the event
of coolant loss, the cooling system should be inspected immedi ­
ately by your authorized Audi dealer . It is not enough merely to add
coolant.
In a
sealed system, losses can occur only if the boiling point of the
coolant is exceeded as a result of overheating. ..,.