2008 AUDI A4 AVANT sensor

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& WARNING
Always read and heed all WARNINGS and other important informa­
tion
=> page 180.
[ i] Tips
The seat height adjustment on the front seats can also be used the adjust the position of the safety belts .•
Improperly worn safety belts
Incorrectly positioned safety belts can cause severe inju­
nes.
Wearing safety belts improperly can cause serious injury or
death. Safety belts can only work when they are correctly
positioned on the body. Improper seating positions reduce
the effectiveness of safety belts and will even increase the
risk of injury and death by moving the safety belt to critical
areas of the body . Improper seating positions also increase
the risk of serious injury and death when an airbag deploys and strikes an occupant who is not in the correct seating position. A driver is responsible for the safety of all vehicle
occupants and especially for children. Therefore:
- Never permit anyone to assume an incorrect sitting posi­
tion in the vehicle while
traveling =>& .
& WARNING
Improperly worn safety belts increase the risk of serious personal
injury and death whenever a vehicle is being used.
• Always make sure that all vehicle occupants are correctly
restrained and stay in a correct seating position whenever the
vehicle is being used.
Controls and equip­ ment Safety first Vehicle operation
& WARNING
(continued)
• Always read and heed all WARNINGS and other important infor­
mation
=> page 180. •
Safety belt tensioner
How safety belt pretensioners work
In front, side and rear collisions above a particular
severity, safety belts in use are tensioned automatically.
The safety belts are equipped with safety belt pretensioners . The
system is activated by sensors in front, side and rear collisions of
great severity. This tightens the belt and takes up belt
slack=> & in
"Care, service and disposal of safety belt pretensioner". Taking up
the slack helps to reduce forward occupant movement during a collision .
0 Note
Never let the belt remain over a rear seat back that has been folded
forward. The rear belt pretensioner will be activated unnecessarily
in a collision and then has to be replaced .
[ i] Tips
The safety belt pretensioner can only be activated once.
• In minor frontal, side and rear -end collisions, in a rollover and in
accidents involving very little impact force, the safety belt preten­
sioner are not activated.
• When the safety belt pretensioner is activated, a fine dust is
released. This is normal and is not caused by a fire in the vehicle.
• The relevant safety requirements must be observed when the
vehicle or components of the system are scrapped. A qualified
deal -_,,.
Vehicle care Do-it-yourself service Technical data

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&, WARNIN G (continu ed )
• The inflating airbag will hit the child s afety seat or infant
car rier with gre at for ce and will sma sh the child safe ty se at and
c hild agai nst the ba ckre st, center arm re st, door , or roof .
• Alwa ys in sta ll re arw ard -f aci ng child re str aint s in the b ack se at .
• If you mu st in stall a rearw ard facing child safety seat on the
front p assenger se at be cause of e xce pti ona l ci rc um stan ce s a nd
the PASSENGER AIR BAG OFF light doe s not come on and stay on ,
immedi atel y insta ll the re ar-f a cing child s afet y s ea t in a re ar
se ating position and h av e the airb ag sy stem inspe cted by your
Audi dealer .
& WARNING
If, in e xception al c ir cum sta nces, you mu st in sta ll a forward -f ac in g
c hild re straint on the front p assenger 's seat:
• Alway s mak e sure the forward-f acing seat ha s been designed
and certified by it s manufacturer for u se on a front seat with a
p asseng er front and side airb ag .
• Never put the forw ard -fa cing child re straint up again st or very
near the instrument panel.
• Alway s move the p assenger seat into it s re armost position in
the se at's fore and aft adju stment range , as far a way from the
a irbag a s pos sible , before installing the forward -f a cing child
rest raint . The ba ckrest must be ad justed to an upright po sitio n.
• Make sure that the PASSENGER AIR BAG OFF light come s on
a nd stay s on all th e time whenever the ignit ion i s swi tched on .
•
Advanced Airbag System components
The front passenger seat in your vehicle has a lot of very impo rtant
parts of the Advanced A irbag System in it . These parts include the
we ight -sensing mat , sensors, wiring, brackets , and more. The func -tion of the system in the front passenger seat is checked by the e
lec ­
tronic contro l unit w hen t he ignit ion is on . The co ntrol uni t monitors
the Advanced Airbag System and turns the airbag indicator light on
whe n a malfunction i n the system components is detected. T he
function of the airbag ind icator light is described in greater detai l
below. Because the front passenger seat contains important parts
o f 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 do ing its job in
a crash .
The front Adva nc ed Airbag S ystem consi sts of th e
following :
• Crash sensors in the front of the ve hicle that measure veh ic le
acce leration/deceleration to provide information to the Advanced
A irbag System about t he severity of t he crash .
• An electronic control unit, with integrated crash sensors for front
and side impacts. The control unit "dec ides" whethe r to fire the
front airbags based on the information received from the crash sensors . The control unit also "dec ides" whether the safety be lt
pretensioners should be activated.
• A dual -stage Advanced Airbag with gas generator for the driver
inside the steering wheel hub.
• A dual-stage Advanced A irbag and gas generator inside the
instrument pane l for the front passenger .
• A we ight -sensing mat under the upholstery padding of the front
passenger seat cushion that measures the tota l weight on the seat .
T he information registered is sent continuously to the electronic
control un it to regu late dep loyment of the front Advanced Airbag on
the passenger side .
• An airbag monitor ing system and indicator light in the instru ­
ment
cluster=> page 198 .
• The PASSENGER AIR BAG OFF light comes on and stays on in t he
center of the instrument panel
=> page 199, fig . 180 and te lls you
when the fron t Advanced Airbag on the passenger side has been
turned off.
~

Airbag system 111111
-------------------------------------------- -=-:~--___.
• A sensor below the safety belt latch for the front seat passenger
t o m easure the tens io n on t he sa fety be lt. T he tension on the safe ty
belt and the weight registered by the weight -sensing mat help the
contr ol unit "decide" whe the r the front ai rbag for the fron t
passenger seat should be turned off or
not=> page 189, "Child
r est ra ints on the front seat - some important th ings to know".
• A sensor in the safety belt latch for the driver and for the front
seat passenge r that senses whether t hat safety bel t is la tched or no t
and transmits this information to the e lectronic control unit.
& WARNING
Damage to the front pas senger seat can pre vent the front airbag
from working properly.
• Improper repair or disassembly of the front passenger and
driver seat will prevent the Advanced Airbag System from func ­
tioning properly .
• Repairs to the front passenger seat must be performed by qual ­
ified and properly trained workshop personnel .
• Never remove the front pa ssenger or driver seat from the
vehi cle .
• Ne ver remo ve the upholstery from the front passenger seat .
• Never disassemble or remove parts from the seat or disconnect
wires from it .
• Never carry sharp objects in your pockets or place them on the
seat . If the weight -sen sing mat in the passenger seat i s pun ctured
it cannot work properly.
• Never carry things on your lap or carry objects on the
passenger seat . Such items can increase the weight registered by
the weight -sensing mat and send the wrong informat ion to the
airbag control unit .
• Never store items under the front passenger seat . Parts of the
Advanced Airbag System under the passenger seat could be
d amaged , preventing them and the airbag system from working
properly.
Controls and equip­ ment Safety first
Vehicle operation
& WARNING (continued )
• Never place seat covers or replacement upholstery that have
not been specifically appro ved by Audi on the front seat s.
• Seat covers can prevent the Advanced Airbag System from
recognizing child restraint s or occupants on the front passenger
seat and prevent the side airbag in the seat backrest from
deploying properly.
• Never use cushions, pillows , blankets or similar items on the
front passenger seat. The additional padd ing will prevent the
weight-sensing mat in the seat from accurately registering the
child restraint or person on the seat and prevent the Ad vanced
Airbag System from functioning properly .
• If you mu st use a child re straint on the front pas senger seat
and the child restraint manufacturer's instru ctions require the use
of a towel , foam cu shion or something el se to properly position
the child restraint , make certain that the PASSENGER AIR BAG OFF
light comes on and stays on whenever the child restraint i s
installed on the front passenger seat.
• If the PASSENG ER AIR BAG OFF light does not come on and stay
on , immed iately install child re straint in a re ar seat ing position
and have the airbag sy stem inspected by your Audi dealer . •
How the Advanced Airbag System
components work together
The front Advanced Airbag System and the side airbags supplement
the prote ction off ered by the fro nt three -p oi nt safe ty belts with
pretensioners and load limiters and the adjustable head restra ints
to help reduce the risk of injury in a wide range of accident and
crash situations. Be sure to read the important informat ion about
safety and heed the WARNI NGS in this chapter.
Dep loyment of the Adva nced Ai rbag Sys tem a nd th e activation of
the safety belt pretensioners depends on the dece leration
measu red by the crash senso rs and registered by the electro nic _.,
Vehicle care Do-it-yourself service Technical data

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PASSENGER AIR BAG OFF light
N
-M -J., a, cc
Fi g. 18 0 Sec tion fr om
t h e i nstr um ent pa nel:
P ASSE NG ER AI R BA G
OFF lig ht
The PASSENGER AIR BAG OFF light is located in the center o f the
ins trumen t panel
=> fig . 180 .
The PASSENGER AIR BAG OFF light wil l come on and stay on to te ll
you when the front Advanced Airbag on the passenger side has been turned off by the electronic control unit. Each time you turn on
the ign it ion, the
PA SS ENGER AIR BA G OFF light wi ll fl as h for a few
seconds and :
• will stay on if t he front passenger seat is not occupied,
• will stay on if there is a small child or chi ld restraint on the front
passenger seat,
• will go out if the front passenger seat is occupied by an adult as
registered by the we ight -sens ing mat.
The
PA SS ENGER AIR B AG OFF light mu st come on and stay on if the
ignition is on and
• a car bed has been instal led on the front seat, or
• a rearward -facing chi ld restraint has been installed on the front
passengerseat,or
Controls and equip­ ment Safety first
Vehicle operation
• a forward -facing child restraint has been instal led on the front
passenger seat, or
• the weight register ed on the front passenger seat is equa l to or
less than the combined weigh t of a typica l 1 year-old restrained in
one of the rear -facing or forward -facing infant restraints listed in
Federa l Motor Veh ic le Safe ty S tandard
208 with wh ich the Advanced
Airbag System in your vehicle was certified .
If the front passenger seat is not occupied, the front airbag will not
dep loy, and the
PA SS ENGER AIR BAG OFF light will stay on . Never
insta ll a rearward -facing child restraint on the front passenger seat,
the safest place for a child in any kind of ch ild restraint is at one of
the seating positions on the rear
seat => page 189, "Ch ild restraints
on the front sea t-some important things to know"
and => page 210,
"Chi ld Safety" .
If the PASSENGER AIR BAG OFF light comes on when one of the
condit ions listed above is met , be sure to check the light regu lar ly
to make certain that the
PA SSENGER AIR BAG OFF light stays on
cont inuously whenever the ignition is on . If the PASSENGER AIR
BAG OFF light does not appear and not stay on all the time , stop as
soon as it is safe to do so and
• reactivate the system by turning the ignition off and then turning
it on again;
• remove and reinstall the ch ild restraint. Make sure that the child
res tra int is proper ly instal led and t hat t he sa fety be lt for the front
passenger seat has been correctly routed around the child restraint
as described in the chi ld restraint manufacturer's instructions;
• make sure that the convertible locking feature on the safety belt
for the front passenger seat has been activated a nd that the safety
belt has been pulled t ight . The belt must not be loose or have loops
of slack so t hat t he sensor below t he safety belt latch on the seat can
do its job
=> page 220.
• make s ure that th ings that may inc rease the we ight of the child
and child safety seat are not being transported on the front
passenger seat;
Vehicle care Do-it-yourself service Technical data

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• make sure that the safety belt tension sensor is not blocked.
Shake the safety belt latch on the front passenger seat back and
forth;
• If a strap or tether is being used to tie the child safety seat to the
front passenger seat, make sure that it is not so tight that it causes
the weight -sensing mat to measure more weight than is actually on
the seat.
If the PASSENGER AIR BAG OFF light still does not come on and does
not stay on continuously (when the ignition is switched on),
• take the child restraint off the front passenger seat and install it
properly at one of the rear seat positions. Have the airbag system
inspec ted by your Audi dealer immediately .
• move the child to a rear seat position and make sure that the
child is properly restrained in a child restraint that is appropriate for
its size and age.
The
PASSENGER AIR BAG OFF light should NOT come on when the
ignition is on and an adult is sitting in a proper seating position on
the front passenger seat. If the
PASSENGER AIR BAG OFF light
comes on and stays on or flashes for about 5 seconds while driving,
under these circumstances, make sure that:
• the adult on the front passenger seat is properly seated on the
center of the seat cushion with his or her back up against the back ­
rest and the backrest is not
reclined~ page 168, "Proper occupant
seating positions",
• the adult is not taking weight off the seat by holding on to the
passenger assist handle above the front passenger door or
supporting their weight on the armrest,
• the safety belt is being properly worn and that there is not a lot
of slack in the safety belt webbing,
• accessory seat covers or cushions or other things that may cause
an incorrect reading or impression on the weight-sensing mat
under the upholstery of the seat have been removed from the front
passenger seat, •
a safety belt extender has not been left in the safety belt latch for
the front passenger seat.
In addition to the
PASSENGER AIR BAG OFF light in the center of the
instrument panel, the message
PASSENGER AIR BAG OFF or
PASSENGER AIR BAG ON will briefly appear in the instrument cluster
display. This is to inform the driver of the current front passenger
airbag status. •
Important safety instructions on monitoring
the Advanced Airbag System
& WARNING
An airbag system that is not functioning properly cannot provide
supplemental protection in a frontal crash.
• If the airbag indicator light comes on, it means that there may
be something wrong with the Advanced Airbag System. It is
possible that the airbag will inflate when it is not supposed to, or
will not inflate when it should.
• Have the airbag system inspected immediately by your Audi
dealer.
& WARNING
If the front airbag inflates, a child without a child restraint, in a
rearward-facing child safety seat or
in a forward-facing child
restraint that has not been properly installed will be seriously
injured and can be killed .
• Even though your vehicle is equipped with an Advanced Airbag
System, make certain that all children, especially 12 years and
younger, always ride on the back seat properly restrained for their age and size .
• Always install forward or rear-facing child safety seats on the
rear seat -even with an Advanced Airbag System.
.,_

-Airbag system ---=--.:..,.._ _________________________________ _
&, WARNING (continued )
cellular telephones and CB radios, etc .) 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 authorized Audi dealer or qualified workshop .
• Never modify the front bumper or parts of the vehicle body .
• Always make sure that the side airbag can inflate without inter ­
ference :
- Never install seat covers or replacement upholstery over the
front seatba cks that have not been specifically approved by
Audi.
- Never use additional seat cushions that cover the areas
where the side airbags inflate.
- 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 .
• The airbag system can be activated only once. After an airbag
has inflated , it must be replaced by an authorized Audi dealer or
qualified technician who has the technical information , training
and special equipment necessary.
• The airbag system can be deployed only once. After an airbag
has been deployed, it must be replaced with new replacement
parts designed and approved especially for your Audi model
version. Replacement of complete airbag systems or airbag
components must be performed by qualified workshops only .
Make sure that any a irbag service action is entered in your Audi
Maintenance
& Warranty booklet under AIRBAG REPLACEMENT
RECORD .
• In accidents when an airbag is deployed, the vehicle battery
separates the alternator and the starter from the vehi cle electrical
system for safety reasons with a pyrotechnic circuit interrupter.
-Work on the pyrotechni c circuit interrupter must only be
performed by a qualified dealer -risk of an accident !
&, WARNING (continued )
-If the vehicle or the circuit interrupter is scrapped, all appli­
cable safety precautions must be followed.
•
Other things that can affect Advanced Airbag performance
Changing the vehic le 's suspension system can change the way that
t he A dvance d Ai rbag S ystem p erf o rm s in a c rash. F or example,
using tire -rim combinations not approved by Audi, lowerin g the
ve hicle , ch ang ing the stiff ness of the suspe nsion, includ ing the
springs, suspension struts, shock absorbers etc. can chang e the
fo rces that a re measured by the airbag senso rs and se nt to the elec­
tronic control u nit. Some suspension chan ges can, for exampl e,
i n crease the fo rce level s measured by the sen so rs and ma ke the
a irbag s yste m de plo y in cras he s in w hi ch it wou ld not de ploy if th e
changes had not been made. Other kinds of changes may reduce
t h e fo rce lev els measu red by the senso rs a nd p reven t the airb ag
from dep loying when it should.
T he sens ors i n the safe ty belt buckle f or the dri ve r and front
passeng er seat tell t he electronic contro l modu le if the safety belt is
la tched o r not. If t he sa fe ty bel t i s being used, the fro nt ai rbag wi ll
deploy at a s ligh tly high er rate o f veh icle dece lerat io n th an if th e
safety be lt is not being u sed . Th erefo re , in a particula r co llision, it is
poss ib le th at a n airbag will not deplo y at a seat ing po sit io n wh ere
the safety be lt is being used but wi ll inflate at the pos ition where the
safety be lt is not bei ng used . It is im po rta nt tha t noth ing i nte rfere
with the safety belt buc kles so that the sensors can send the correct
i nf orm atio n abou t s afe ty belt use to th e electr onic co ntrol uni t.
~

& WARNING
Changing the vehicle's suspension including use of unapproved
tire-rim combinations can change Advanced Airbag performance and increase the risk of serious personal injury in a crash.
• Never install suspension components that do not have the
same performance characteristics as the components originally
installed on your vehicle.
• Never use tire-rim combinations that have not been approved
by Audi.
& WARNING
Items stored between the safety belt buckle and the center
console can cause the sensors in the buckle to send the wrong
information to the electronic control module and prevent the
Advanced Airbag System from working properly .
• Always make sure that nothing can interfere with the safety
belt buckles and that they are not obstructed . •
Safety first
Airbag system
Side airbags
Description of side airbags
The airbag system can provide supplemental protection
to properly restrained occupants.
Fig. 181 Side airbag
location in the driver's
seat
The side airbags are located in the sides of the front seat backrests
=> fig. 181 and the rear backrest* facing the doors. They are identi­
fied by the word "AIRBAG".
The side airbag system basically consists of: • the electronic control module and external side impact sensors
• the two side airbags located in the sides of the front backrests
• two rear side airbags (as an ordered
option)
• the airbag warning light in the instrument cluster .
Th e airbag system is monitored electronically to make certain that
it is functioning 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, front and rear*
.,_
irechnical data

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passenger's upper torso on the side of the vehicle that is struck in a
side co llis ion. The airbag dep loys on ly in side impacts and only
when the vehic le acce leration registered by the control unit is high
enoug h. If this rate is below the reference va lue programmed into
the control unit, the side airbags will not be triggered, even though
the car may be badly damaged as a resu lt of the collision . It is not
possible to define an airbag trigger ing range that wi ll cover every
possible angle of impact, since the circumstances will vary consid ­
erab ly between one coll ision and another. I mportant factors
inc lude, for example, the nature (hard or soft) of the impacting
object, the angle o f impact, vehicle speed,
etc .=> page 205, "I m por ­
tant safety instructions on the side airbag system".
Aside from their normal safety funct ion, safety be lts work to help
keep the driver or front passenger in posit ion in the event of a side
collision so t hat the side airbags can provide protection.
The airbag system is
not a substitute for your safety belt. Rather, it
is part of the overa ll occupant restraint system in your vehicle .
A lways re m ember that t he side airbag system can on ly he lp to
protect you if you are wearing your safety be lt and wearing it prop ­
e rly. This is a nother reason why yo u should a lways wear you r safety
belts, not just because the law requires you to do
so=> page 176,
"General notes".
It is important to re m em ber that while the supp lemental side airbag
system is designed to reduce the like lihood of serious injuries, other
injuries, for example, swel ling, bru is ing, and minor abrasions can
a lso be associated with deployed side airbags. Remember too, side
a irbags wil l deploy o nly once and on ly in certain kinds of accidents
- your safety belts are a lways there to offer protection.
Vehicle damage, repair costs or even the lack of vehic le damage are
not necessari ly an indication of over-sensitive or failed airbag acti ­
vation. In some collisions, both front and side airbags may inflate.
Reme mber too, that a irbags w ill dep loy on ly once and on ly in
certain kinds of col lisions -your safety belts are always there to
offer pro tec tion in those acc ide nts in whic h airbags are not
supposed to deploy or when they have already deployed. T
he s ide a irbag sys te m will not d eplo y:
• whe n the ign ition is turned off
• in side collisions when the acce leration measured by the sensor
is t oo low
• in front-end co llisions
• in rear-end co llisions
• in ro llovers .
I n some types of accidents the front airbags, side curta in airbags
and side airbags may be triggered together.
& WARNING
• Safety belt s and the airbag sy stem will only prov ide protection
when occupant s are in the proper se ating posit ion
=> page 2 05 .
• If the airbag indic ator light come s on when the vehicle i s being
u sed , ha ve the sy stem inspe cted immed iat ely by y our authorized
Audi d ealer . The airbag may not work properly when the vehicle
a cc eler ation in a side colli sion is high enough to acti vate the
airba g.•