engine AUDI S8 2015 Repair Manual

212 Trailertowing
drive at the maximum permissible speed. Re­
duce your speed even more if load, weather or
wind condit ions are unfavorable -part icu larly
when going downhill.
Reduce vehicle speed
immedi atel y if the trail ­
er shows the slightest sign of swaying .
Do not
tr y to stop th e sway ing by acceler ating .
Observe speed limi ts. In some areas, speeds
for vehicles towing trailers are lower than for
regular vehicles .
A lways apply brakes early. When driv ing
downhill, shift into a lower gear to use the en­
gine braking effect to slow the vehicle . Use of
the brakes a lone can cause them to overheat
and fail.
Coolant t emperature
The coolant temperature gauge¢ page 10
must be observed carefully. The coolant tem­
perat ure can increase if you drive on long in ­
clines in a low gear at high engine speeds. Re­
duce your speed immediate ly if the L EDs in
the top part of the display turn on.
F or more in formation about indicator lights,
referto .¢page
15 .
A WARNING
Anyone not properly restrained in a mov­
ing veh icle is at a much greater risk in an
accident . Never let anyone ride in your car
who is not properly wear ing the restra ints
provided by Aud i.
Trailer towing tips
Important to know
Your vehicle hand les different ly when towing
-
a trailer because of the addit ional weight and
d ifferent weight distribution . Safety, perform­
ance and economy w ill greatly depend on how
carefully you load your trailer and operate
your ng.
Before you actually tow your trailer, practice
turning, stopp ing and back ing up in an area
away from traffic . Keep practicing until you have become completely familiar with the way
your vehicle-trailer combination behaves and responds .
Backing up is diffi cult and requ ires practice .
Backing up with a trailer gene rally req uires
steering action opposite to that when backing
up your vehicle without a tra iler.
Maintain a greater d ista nce between you r ve­
hicle and the one in front of you . You wi ll need
more room to stop. To compensate for the
trailer, you w ill need a larger than normal
turning rad ius.
When passing, remember that you cannot ac ­
ce lerate as fast as you norma lly would be­
ca use of the added load. Make sure yo u have
enough room to pass. After passing, allow
plenty of room for your trailer be fore chang­
ing lanes again .
Avoid jerky starts, sharp turns or rapid lane changes.
(D Tips
- Do not tow a trailer during the break-in
period of your vehicle .
- If you tow a trailer, your Audi may re ­
quire more frequent maintenance due to
the extra load¢
page 290.
Parking on a slope
Do not park on a slope with a trailer. If it can­
not b e avoided, do so only after doing th e fol­
lowing:
When par king:
.,. App ly the foot brake.
.,. Have someone p lace chocks under both the
vehicle and the tra iler wheels .
.,. With chocks in place, slowly release the
brakes unt il the wheel chocks absorb the
load .
.,. Turn the whee ls towards the curb .
.,. Apply the parking brake .
.,. Select the P se lector lever posit ion.
When re starting after parking:
.,. App ly the foot brake.

,....,
N ,....,
N
0 J:
'SI: ,...., \!) 1.1'1 ,...., 1.1'1 ,....,
~ Start the engine.
~ Se lect the D selector lever position.
~ Re lease the park ing brake and slowly pull
out and away from the wheel chocks .
~ Stop and have someone retrieve the wheel
chocks.
(D Tips
If you move the selector lever of the auto­
matic transm ission to P before applying
the parking brake and before blocking the
wheels, you may have to use more force
later to move the lever out of the P posi­
tion .
Trailer towing 213
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220 Fuel supply and filling your fuel tank
Fuel supply and filling
your fuel tank
Gasoline
Fuel supply
Appl ies to vehicles: with gasoline engine
Using the right fuel helps keep the environ­
ment clean and prevents engine damage .
Fuel recommendation
The fuel recommended for yo ur vehicle is un ­
l e aded premium
grade gasoline . Audi recom­
mends using TO P TI ER D ete rgent Gaso line
wi th a m inimum octane ra ting o f 91 A KI ( 95
RO N). Fo r more informa tio n o n TOP TIER De­
tergent Gasoline, p lease go to the o fficia l
websi te (www. topt iergas .com) .
The re commended gasoline octane rati ng for
your engine can a lso be fo und o n a label loc at­
ed on the ins ide of the fuel filler flap . This ra t­
ing may be specif ied as AK I or RO N.
Your veh icle may also be operated using un­
l eaded regular gasoline with a minimum oc ­
tane rating of 87 AKI/91 RO N. However, using
87 A KI/91 RON octa ne fue l wi ll slightly re ­
d uce eng ine perfo rmance .
Use unleaded ga soline only. U nleaded g aso­
l ine is available th rougho ut the USA, Canada,
a nd i n most E uropean countries . We recom ­
mend that you do not ta ke yo ur vehicle to
areas or co untries where unleaded gasoline
may not be ava ilable.
F or mo re informat io n on refue ling your ve hi­
cle, see~
page 222.
Octane rating
Octane rating ind icates a gaso line's abili ty to
res ist eng ine dam ag ing "knoc k" ca use d by
premature ign ition and detona tion. Therefore,
buy ing the correct grade of gaso line is very
important to he lp prevent possible engine
damage and a loss of engine performance.
Gasoline mos t commonly used in the Unite d
States and Canada has the following octane r
atings t hat can usu a lly be found on the fi ller
pump:
- Premium Gra de: 91 -96 A KI
- Regular Grade : 87 -90 AKI
Explanation of the abbreviations:
AKI = Anti K nock In d ex = (R+M )/2 = (RON
+ MON)/2
R ON= Resear ch Octane Numb er
MON = Motor Octane Num ber .
(D Note
-Do not use a ny fue l w it h o ctane rat ings
lower tha n 87 A KI or 91 RO N othe rwise
expensive engi ne damage w ill occur.
- Do
not use leaded gasoli ne. The use of
leaded gasoline w ill severely damage
yo ur v ehicle's cata lytic co nve rter and its
ability to co ntrol exha ust em issions .
Blended gasoline
Applies to vehicles: with gasoline engine
Use of gasoline containing alcohol or
MTBE (methyl tertiary butyl ether )
You may use unleaded g asoline blende d wi th
alcohol o r MTBE (commonly referred to as
oxygenates) if the blende d mixture meets t he
f o llow ing criteria:
Blend of gasoline methanol (wood alcohol or
methyl alcohol)
- Anti -kno ck index must be 87 A KI or higher.
- Blend must contain no more t han 3% meth-
anol.
- Blend must contain more than 2% co -sol -
vents.
Blend of gasoline and ethanol (grain alcohol
or ethyl alcohol)
- Anti -knock index must be 87 AKI or higher .
- Blend must not conta in mo re tha n 10%
ethanol.
Blend of ga soline and MTBE
- Anti-knock index must be 87 AKI or higher. IJll,

,....,
N ,....,
N
0 J:
'SI: ,...., \!) ..,.,
,...., ..,., ,....,
-Blend must contain not more than 1S%
MTBE.
Seasonally adjusted gasoline
Many gasoline grades are blended to perform
espec ially we ll for winter or summer driving.
During seasonal change-over, we suggest that
you fill up at busy gas stat ions where the sea­
sonal adjustment is more likely to be made in
time .
(D Note
-Methanol fuels which do not meet these
requirements may cause corrosion and
damage to plastic and rubber compo­
nents in the fuel system.
- Do not use fue ls that fail to meet the
specified criter ia in this chapter.
- If you are unable to determine whether
or not a particular fue l blend meets the
specifications, ask your service station or
its fuel supp lier.
- Do not use fuel for which the contents
cannot be identified.
- Fuel system damage and performance
problems resulting from the use of fuels
different from those specified are not
the responsibility of Audi and are not
covered under the New Vehicle or the Emission Control System Warranties.
- If you experience a loss of fuel economy
or driveability and performance prob­ l ems due to the use of one of these fuel
blends, we recommend that you switch
to unblended fuel.
Gasoline additives
Appl ies to vehicles : wit h gasoli ne e ng in e
A majo r concern among many auto manufac­
ture rs is carbon deposit build-up caused by
the type of gasoline you use.
Although gasoline grades differ from one manufacturer to another , they have certain
things in common. All gasoline g rades contain
substances that can cause deposits to collect
on vital engine parts, such as fuel injectors
and intake valves. Although most gasoline
Fuel supply and filling your fuel tank 221
brands include additives to keep engine and
fuel systems clean, they are not equally effec­
tive .
Audi recommends using TOP TIER Detergent
Gasoline . For more information on TOP TIER
Detergent Gasoline, please go to the official
webs ite (www.toptiergas.com).
After an extended per iod of using inadeq uate
fuels, carbon deposit build-ups can rob your
engine of peak performance.
(D Note
Damage or malf unct ion due to poor fuel
quality is not covered by the Audi New Ve­
hicle Limited Warranty.
Diesel fuel
Applies to veh icles : w ith diese l en gine
Always use ULSD (Ultra Low Sulfur Diesel)
No. 2. The ULSD No. 2 meets the ASTM D97S.
Diesel fuel with concentrations of biodiesel
highe r than S % such as Bll, B2O or BlOO are
strictly prohib ited .
Se rv ice stat ion fuel pumps are labeled with
the cor rect fuel informat ion for easy recogn i­
tion by the user. If the diesel fuel pump is not
labeled ask the station operator what fuel is
being dispensed before filling up your vehicle.
ULSD No. 2 may not be available outside the
USA and Canada. Be sure to check before trav­
eling to other countries .
Winter operation
ULSD No. 2 can become thicker in the winter .
Because of this, gas stations sell ULSD No. 2
with imp roved flow when cold during the win­
ter. Ask the gas stat ion attendant if the diesel
sold is winterized sufficient ly for the current
and the predicted temperatures.
If not winterized o r insuff icient ly w interized
ULSD No. 2 has already thickened to the ex­
tent that the engine will not start, warm the
vehicle up by leaving it in a heated garage.
Ill-
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222 Fuel su ppl y and fillin g yo ur fu el t an k
Cold diesel engines normally produce louder
noises during winter conditions than during
warmer periods . In addition, the exhaust gas ­
es may be light blue in color until the engine has warmed up.
.&_ WARNING
Never use starting assist fluids. They may
be potentially explos ive or cause a "run­
away" engine condition . Th is could resu lt
in ser ious persona l injury and eng ine dam­
age.
- Your vehicle's diesel engine was de­ signed so ley for use with ULSD No. 2.
Therefo re, never use gaso line, heat ing
oi l or other fuels. These fuels contain
substances that will severely damage the
fuel system and the engine. Such dam­
age will not be covered by your New Ve­ hicle limited Warranty.
- If you put any amount of incorrect fue l in
the fue l tank, do not start the engine un­
der any circumstances. Immediately con­
tact the nearest authorized Audi dealer
or authorized Audi Service Facility for as­
s istance. These fuels contain substances
that can severely damage the fuel sys­
tem and the engine if the engine is start­
ed .
- Do not mix additives such as "flow im­
provers", gasoline or other substances
with ULSD No. 2.
Fuel tank
Fuel filler neck
The fuel filler neck is located on the right rear
side panel behind the fuel filler flap .
If the power locking system should fail, you
can still open the flap manually- for detailed instructions see
c> page 2 2 4 .
You can f ind the fue l tank ca pa city of your ve­
hicle in
<=> page 288.
The label on the inside of the fuel f iller flap
te lls you the correct fue l for your vehicle. For
more information about fuel specifications,
see
c> page 220.
Your vehicle fuel tank has an on board refuel­ ling vapor recovery system. This feature helps
to prevent fuel vapors from escaping from the
tank and polluting the environment while you
refuel your vehicle. In order to fill the tank
proper ly while protecting the environment,
please follow this refueling procedure careful­
ly .
.&_ WARNING
Under normal operating cond itions , never
ca rry addit ional fue l conta iners in your car .
Gas canisters and other containers used to
transport fuel can be dangerous. Such con­
tainers, fu ll or empty, may leak and could
cause a fire in a collision. If you must
transport fuel to use for your lawn mower,
snow b lower, etc ., be very careful and al­
ways observe local and state laws regard­
i ng the use, transportation and storage of
such fuel containers. Make certa in the con­
tainer meets industry standards (ANSI/
ASTM
F852 -86).
{(y Note
Never drive your veh icle until the fuel tank
i s completely empty. The irregula r supply
of fue l can cause misfir ing. Gasoline cou ld
enter the exhaust system and damage the
catalytic converter.

Refuelling
Fig. 190 Right rear vehicle sid e: Opening t he fuel filler
flap
Fig. 191 Fu el filler flap with attached fuel cap
When activating the central locking, the fuel
filler flap is automatically unlocked or locked.
Refuel the vehicle with the ignition switched
off.
Taking the fuel cap off
• Press the left side of the fuel filler flap to
open it¢
fig. 190 -arrow- .
• Unscrew fuel filler cap counter-clockwise
and hang it on the fuel filler flap
r;, fig. 191.
• Check the label on the inside of the fuel fill­
er flap to determine if the vehicle must be
fueled with gasoline or diesel fuel.
Refuelling procedure
• Insert the fuel nozzle from the gasoline
pump into the fuel filler neck as far as it will
go.
• Select a medium refuelling rate so that the
nozzle switches off automatically when the
tank is full.
Putting the fuel cap back on
• After filling your tank, twist the fuel filler
cap clockwise as far as it will go.
• Close the fuel filler flap.
Fuel supply and filling your fuel tank 223
To avoid fuel spilling or evaporating from the
fuel tank always close fuel filler cap properly
and completely. An improperly closed fuel fill­
er cap may also cause the MIL lamp¢
page 29
to come on (only vehicles with gasoline en­
gine).
A WARNING
-
Improper refueling or handling of fuel can
cause fire, explosion and severe burns.
- Fuel is highly flammable and can cause
severe burns and other injuries.
- Failure to shut the engine off while refu­
eling and/or to insert the pump nozzle
fully into the fuel filler neck could cause
fuel to spray out of filler neck or to over­
flow. Fuel spray and overflowing fuel can
cause a fire.
- Never use a cellular telephone while re­
fueling. The electromagnetic radiation
can cause sparks that can ignite fuel va­
pors and cause a fire.
- Never get back into your vehicle while re­
fueling. If in exceptional circumstances
you must get back in your vehicle while
refueling, make certain that you close
the door and touch metal to discharge
static electricity before touching the fill­
er nozzle again. Static electricity can
cause sparks that can ignite fuel vapors
released during refueling .
- Never smoke or have an open flame any­
where in or near your vehicle when refu­
eling or filling a portable fuel container.
- For your safety, we strongly recommend
that you do not travel with a portable
fuel container in your vehicle. The con­
tainer, full or empty may leak and could
cause a fire, especially in a crash.
- If, under exceptional circumstances, you
must transport a portable fuel container,
please observe the following:
- Never fill a portable fuel container
while it is anywhere in or on the vehicle
(for example, in the luggage compart­
ment, or on the trunk). Static electrici­
ty can build up while filling and can ig-
nite fuel vapors causing a fire. .,.
'------------=---------

224 Fuel supply and filling your fuel tank
-Always place a portable fuel container
on the ground before filling.
- Always keep the fi ller nozzle complete­
ly inside the portable conta iner before
and during filling.
- If filling a portable container made of
metal , the filler nozz le must always be
in contact with the container. This will
help prevent static electricity from dis­
charging and cause a fire .
- Never spill fuel inside the vehicle or
luggage compartment. Fuel vapors are
highly flammable .
- Always observe local and state/provin­
cial laws regarding the use, storage
and transportation of fuel conta iners .
- Make certain the fuel container meets
industry standards (ANSI/ ASTM
F852 -86) .
Q) Note
If any fuel has spilled onto the car, it
should be removed immediately to prevent
damage to the paint.
@ For the sake of the environment
As soon as the correctly operated nozzle
sw itches off automatically for the first
time, the tank is full. Do not try to add
more fuel because fuel may spill out. In
add ition, the expansion space in the fuel
tank will be filled -caus ing the fue l to
overflow when it becomes warm and pol­
lute the env ironment.
@ Tips
- Running yo ur engine while refuelling
may cause vapors to escape or
even
cause fue l to spill out of the tank. This
would then shut off the fuel nozzle be­
fore the tank is full.
- Do not refuel your vehicle with the igni­
tion switched on . The fuel gauge may
otherwise not indicate the correct fuel
level after refuelling.
- Diesel vehicles* are equipped with a die­
se l m isfueling protector.
It allows the vehicle to be
fueled only with a diesel
fuel pump nozzle . A worn or damaged
nozzle or a nozzle that is too small may
not be ab le to open the diesel misfueling
protector. If this is the case, try turning
the nozzle before inserting it in the fuel
filler neck, use a different fuel pump or
see your authorized Aud i dealer or au­
thorized repair facility for assistance.
- The fuel filler flap of your vehicle is not
locked when you lock the vehicle from
the inside .
Fuel filler flap emergency release
You can open the fuel filler flap by hand if the
power locking system should fail.
Fig. 192 V ehicl es with sele cti ve catalytic re d uc tion :
Right s ide tri m pan el
Fig. 19 3 Right s ide trim pan el in th e luggage compart·
m ent: em erg enc y re le ase m echani sm
The emergency release mechanism is located
behind the right side trim panel in the lug­
gage compartment. In vehicles with selective
catalyt ic re duction* , re move th e vent gr ill e
first :
... Press both tabs@q
fig. 192 and tilt the
vent gr ille downward. You can then remove
the grille upward . ..,_

.. Loosen the loop C? fig. 193 from the retaine r
and then pull on t he loop carefully
~CD-
.. Press on the left s ide of the fuel filler door
to open C?page 223, fig. 190.
(D Note
Only pull on the loop until you feel resist­
ance. You will not hear it release . Other­
w ise you could damage the emergency re­
lease mechanism .
Selective catalytic
reduction
General information
Applies to vehicles: with d iesel e ng in e
On vehicles w ith select ive catalytic reduction,
an urea solut ion (Ad Blue) is injected into the
exhaust system befo re a nitrogen oxide cata ­
lytic converter to reduce nitrogen emiss ions .
The AdBlue is stored in a separate tank in the
ve hicle. The Ad Blue usage accounts for ap­
prox imately 0 .5% to 1.2% of the diesel fuel
that is used .
You must refill the Ad Blue or have it refilled by your authorized Audi dealer or qualified
workshop as soon as the Ad Blue refill mes ­
sage appears in the instrument cluster
C? poge 226.
,& WARNING
Failure to hee d Ad Blue refi ll information in
t he ins trument cl uste r can preven t the ve­
hicle from being s tarted and d rive n. If the
vehicle cannot be driven and an eme rgency
ar ises, persona l injury can occur.
- Always have the Ad Blue tank refilled well
before the tank runs dry .
@ Tips
-The ins trument clus ter display indi cates
the distance remaining that ca n be driv­
en
C? page 225 . If the Ad Blue tank is
complete ly empty, the engi ne will not
start again after the ignition is switched
off.
Fu el suppl y and filli ng your fuel t ank 225
- Ad Blue is req uired by law to ope rate this
vehicle .
Indicator in the instrument cluster
display
Applies to vehicles: wit h diese l engine
The display indicates if the Ad Blue level is low
or if it was filled incorrectly.
Fi g. 194 In strume nt cl uste r: indicator in the d isp lay
AdBlue level low
You w ill be informed if t he Ad B lue in the tank
drops below a certa in level.
Please refill Ad Blue. Range 1500 miles
( 2400 km )
This indicator appears when there is on ly
enough AdBl ue left to drive the distance indi­
cated in the driver information system. Please
add AdBlue.
AdBlue /; Refill AdBlue! Cannot start en­
gine in 600 miles (1000 km) ! See owner 's
manu al
This indicator appears when there is only
enough Ad Bl ue left to d rive the distance indi­
cated in the driver information system. Please
add AdBl ue. Otherwise the engine will not
start again if you stop it once the distance in­
dicated has been driven.
Refill AdBlue! No rest art! See
owner's m anual
T his message appears w hen the Ad Blue tank
is empty. P lease ad d Ad Blue. Otherwise you
will not be able to start the eng ine again once
you stop it. ..,.

226 Fuel supply and filling your fuel tank
When the minimum AdBlue leve l has been
reached, you must add Ad Blue ¢
page 226.
¢-fi Filling incorrectly
If the Ad Blue tank was filled with a different
fluid than Ad Blue and the system detects that
it is incorrect, a message w ill appear.
Ad Blue../ AdBlue: Sy stem fault No restart
in 600 miles (1000 km)! See owner's man­
ual
This message appears when it is only poss ible
to drive the distance indicated in the dr iver in­
formation system. Drive to the nearest quali­
fied workshop to have the malfunction re­
pa ired. Otherwise the engine will not start
again if you stop it once the distance ind icated
has been driven.
Ad Blue: System fault No restart!
See owner's manual
This message appears if the system detects it
was filled incorrect ly. Drive immed iately to
the nearest qualified workshop to have the
malfunction repaired. Otherwise you will not
be ab le to start the engine again once you
stop it.
Filling AdBlue
Applies to vehicles: with diesel engine
A special refill bottle must be used to fill the
AdBlue .
Fig. 195 Rig ht rear vehicle s ide: removing the Ad B lue
filler cap
Fig. 196 AdBl ue fille r tube: inse rti ng the refill bottle
The Ad Blue filler tube is located near the d ie ­
sel fi ller tube . Always add 1 ga llon (3.8 liters)
of Ad Blue (two bott les) . Th is is the minimum
amount required to ensure the system detects
the refill ing and to start the engine . You can
add a maximum of approxima tely 4 gallons
(16 liters).
Opening the filler tube and adding
AdBlue
Requirement: The request to add Ad Blue must
appear in the instrument cluster display.
" Switch the ignition off.
"O pen the tank cover
r::!> page 223.
"Tur n the Ad B lue filler cap counterclockwise
to remove it
r::!> fig. 195.
"Remove the cap from the refill bottle .
.. Position the refill bottle on the filler tube
and turn the bottle clockwise until it stops
turning (Dr:!>fig .196 .
" Press lightly against the bottom of the bot­
tle @to empty it. Continue pressing the
bottom of the bottle until it is empty or un­
til flu id stops flowing into the tank.
" Turn the bottle to the left w ithout pressing
on the bottom.
Closing the filler tube
" Turn the AdB lue fi ller cap clockw ise on the
fi ller tube until you hear it engage.
" Close the tank cover.
After filling
The vehicle must be driven. The system may
take up to two minutes to detect that the
AdBlue has been f illed. .,.

,....,
N ,....,
N
0 J:
'SI: ,...., \!) 1.1"1 ,...., 1.1"1 ,....,
~ If there was no Ad Blue left in the tank and a
range of
O mi (0 km ) was displayed in the
instrument cluster, switch the ignition on
for about 15 seconds before starting the en­
gine.
_& WARNING
Ad Blue can irr itate the skin, eyes and res­
piratory system . If there is contact with
the fluid, flus h immed iately with plenty of
wate r. Consult a physician if necessary.
(D Not e
-Only use Ad Blue that conforms to the
standard ISO 22241-1. Do not mix any
additives with the Ad Blue and do not di­ l ute it with water .
- Do not add Ad B lue to the diesel tank or
add diesel fuel to the Ad Blue tank. M ix­
i ng can lead to damage to the engine
and the Ad Blue tank system . The Limited
New Vehicle Warranty does not cover
such damage.
- Ad Blue attacks surfaces such as painted
vehicle components, plastic and carpet.
Remove the fluid as quick ly as possib le
with a damp cloth and plenty of cold wa­
ter. If the Ad Blue has already crystal­
lized, use warm water and a sponge.
AdBlue residue that is not removed w ill
crystall ize and can damage the affected
surface.
- Do not store the refill bottle in the vehi­ cle. If it leaks, the escap ing Ad B lue could
damage the vehicle inter ior.
- Do not allow Ad Blue to come into con­
tact with clothing. If there is contact
with the flu id, flush immediately with
plenty of water.
(D Tips
- You can obtain refill bott les from any au­
thorized Audi dealer or other qua lified
workshop.
- Follow the AdBl ue manufacturer's in­
str uctions for usage and sto rage.
Fu el su ppl y and fi lling yo ur fu el t an k 22 7
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