2021 AUDI A4 check engine light

8W1012721BC
Checking and Filling

Checking and Filling
Fuel
Types of gasoline
The correct gasoline grade is stated on the inside
of the fuel filler door.
The vehicle is equipped with a catalytic converter
and must only be driven with unleaded gasoline.
Audi recommends using TOP TIER Detergent Gas-
oline. For additional information on TOP TIER De-
tergent Gasoline, visit www.toptiergas.com.
The individual gasoline grades are differentiated
by octane ratings. This value is given with (R
+M)/2 equating to AKI or in RON.
The headings below match the sticker in the fuel
filler door (examples):
UNLEADED FUEL ONLY MIN. (R+M)/2 87
Regular / MIN. RON 91 Regular
Use regular gasoline with minimum 87 AKI /
91 RON > ©.
Audi recommends using premium gasoline with
minimum 91 AKI / 95 RON to achieve the rated
horsepower and torque.
UNLEADED FUEL ONLY PREMIUM MIN. (R
+M)/2 91 / SUPER MIN. RON 95
Using premium gasoline with minimum 91 AKI /
95 RON is recommended.
If premium gasoline is not available, you can also
use regular gasoline 87 AKI / 91 RON. However
this does reduce the engine power slightly.
UNLEADED FUEL ONLY PREMIUM MIN. (R
+M)/2 93 / SUPER PLUS MIN. RON 98
Using premium plus gasoline with at least 93
AKI / 98 RON is recommended.
If no premium plus gasoline is available, you can
also use premium gasoline with 91 AKI /95 RON.
However this does reduce the engine power
slightly.
CG) Note
— Filling the tank just one time with leaded
fuel or other metallic additives will cause
permanent deterioration to the catalytic
converter function.
— When gasoline with an octane rating that is
too low is used, high speeds or heavy engine
load can lead to engine damage.
@ Tips
The vehicle may be filled with fuel that has a
higher octane rating than what is required by
the engine.
Gasoline mixture
Gasoline with alcohol or MTBE (Methyl-Tert-
Butyl-Ether)
You can use unleaded gasoline mixed with alco-
hol or MTBE (generally labeled as oxygenated
compounds) as long as the fuel meets the follow-
ing conditions:
Gasoline with methanol content (methyl alco-
hol or methanol)
— Anti-Knock Index is at least 87 AKI
—No more than 3% methanol
— More than 2% solvent
Gasoline with ethanol content (ethyl alcohol or
ethanol)
— Anti-Knock Index is at least 87 AKI
—No more than 15% ethanol
Gasoline with MTBE content
— Anti-Knock Index is at least 87 AKI
—No more than 15% MTBE
Gasoline adapted to the season
Many gasoline fuels are adapted to the seasons.
When the season changes, refueling at high-traf-
fic gas stations is recommended. It is more likely
that the gasoline will be suitable for the season
there.
@) Note
— Gasoline with methanol content that does
not meet the specified conditions may cause >
217

8W1012721BC
Checking and Filling

continue fueling, or else the expansion space in
the tank will be filled with fuel.
> After the fuel pump has switched off, wait five
seconds before removing the nozzle to allow
the rest of the fuel to finish dripping into the
fuel tank.
> Turn the fuel cap clockwise until it clicks into
place.
> Close the fuel filler door and then press on the
left side until it latches.
The correct fuel type for your vehicle can be
found on a label located on the inside of the fuel
filler door. For additional information on fuel, see
=> page 217.
For the tank capacity in your vehicle, refer to the
Technical Data > page 287.
To reduce the risk of fuel leaking out or vapors
escaping, make sure that the fuel tank is closed
correctly. Otherwise the Ey indicator light will
turn on.


ZX WARNING
Improper fueling procedures and improper
handling of fuel can lead to explosions, fires,
severe burns, and other injuries.
— Do not smoke. Keep away from open flames.
— The ignition must be switched off when re-
fueling.
— Mobile devices, radio devices, and other ra-
dio equipment should always be switched
off when refueling. Electromagnetic rays
could cause sparks and start a fire.
— If you do not insert the fuel pump nozzle all
the way into the filler tube, then fuel can
leak out. Spilled fuel can ignite and start a
fire.
— Never get into the vehicle when refueling. If
there is an exceptional situation where you
must enter the vehicle, close the door and
touch a metal surface before touching the
fuel pump nozzle again. This will reduce the
risk of electrostatic discharge that can cause
flying sparks. Sparks can start a fire when
refueling.


ZA\ WARNING
Audi does not recommend transporting fuel
containers inside the vehicle. Fuel could leak
out of the container and ignite, especially dur-
ing an accident. This can cause explosions,
fires, and injuries.
—If you must transport fuel in a fuel contain-
er, note the following:
— Always place the fuel container on the
ground before filling. Never fill the fuel
container with fuel while it is inside or on
the vehicle. Electrostatic discharge can oc-
cur while refueling and the fuel vapors
could ignite.
— When using fuel containers made of met-
al, the fuel pump nozzle must always re-
main in contact with the container to re-
duce the risk of static charge.
— Insert the fuel pump nozzle as far as pos-
sible into the filler opening while refuel-
ing.
— Follow the applicable legal regulations in
the country where you are driving when
using, storing and transporting fuel con-
tainers.
— Make sure that the fuel container meets
the industry standards, for example ANSI

or ASTM F852-86.



1) Depending on the engine and country
C) Note
— Remove fuel that has overflowed onto any
vehicle
components immediately to reduce
the risk of damage to the vehicle.
— Never drive until the fuel tank is completely
empty. The irregular supply of fuel that re-
sults from that can cause engine misfires.
Uncombusted fuel may enter the exhaust
system and increase the risk of damage to
the catalytic converter.
@) For the sake of the environment
— Do not overfill the fuel tank, or fuel could
leak out when the vehicle is warming up.
— Fuel should never enter the sewer system or
come into contact with the ground.
219
>

Checking and Filling

@ Tips
The fuel filler door on your vehicle does not
lock if you lock the vehicle from the inside us-
ing
the central locking switch.
Fuel filler door emergency release
Applies to: vehicles with manual fuel filler door release

If the central locking system malfunctions, the
fuel filler door can be unlocked manually.

Fig. 155 Right side trim panel in the luggage compart-
ment: opening the trim panel

Fig. 156 Luggage compartment: fuel filler door emergency
release
The emergency opening mechanism is located
behind the right side trim panel in the luggage
compartment.
> Open the cover in the side panel > fig. 155.
> To unlock the fuel filler door, loosen the red
loop from the retainer and then pull on the
loop carefully > fig. 1569©.
> Press on the left side of the fuel filler door to
open it > page 218, fig. 153.
@) Note
Only pull on the loop until you feel resistance.
You will not hear it release. If you continue to
220

pull, you could damage the emergency re-
lease mechanism.
Emissions control
system
General information
Z\ WARNING
The temperature of the exhaust system is
high, both when driving and after stopping
the engine.

— Never touch the exhaust tail pipes once they
have
become hot. This could result in burns.
— Do not park your vehicle over flammable
materials such as grass or leaves because
the high temperature of the emissions sys-
tem could start a fire.
— Do not apply underbody protectant in the
exhaust system area, because this increases
the risk of fire.
(er) 1 id (Rel Uae lg
Observe the safety precautions > page 220, Gen-
eral information.


The vehicle may only be driven with unleaded
gasoline, or the catalytic converter will be de-
stroyed.
Never drive until the tank is completely empty.
The irregular supply of fuel that results from that
can cause engine misfires. Uncombusted fuel
could enter the exhaust system, which could
cause overheating and damage to the catalytic
converter.
Malfunction Indicator Lamp (MIL)
If the S indicator light blinks or turns on, there
is a malfunction that is causing poor emissions
quality and that could damage the catalytic con-
verter. Drive slowly to an authorized Audi dealer
or authorized Audi Service Facility to have the
malfunction corrected.

8W1012721BC
Checking and Filling

The indicator light can also turn on if the fuel fill-
er cap is not closed correctly > page 218),
Engine compartment
General information
Special care is required if you are working in the
engine compartment
For work in the engine compartment, such as
checking and filling fluids, there is a risk of in-
jury, scalding, accidents, and burns. For this
reason, follow all the warnings and general
safety precautions provided in the following in-
formation. The engine compartment is a dan-
gerous area in the vehicle. > A.
Explanation of warnings (sticker in the engine
compartment):

Hot engine components!
@ Rotating parts!


The radiator fan can switch on at any
[2 time!

High voltage! Switch off the engine be-
5 fore coming into contact with any igni-
tion system components!



The catalytic converter can be damaged
"71 if the oil level is too high!

Always follow the instructions in the op-
Co erating manual.

ZA WARNING
— Turn the engine off.
— Switch the ignition off.
— Set the parking brake.
— Select the “P” (Park) selector lever position.
— Allow the engine to cool.
— Keep children away from the engine com-
partment.
— Never spill fluids on a hot engine. These flu-
ids (such as the freeze protection contained
in the coolant) can catch fire.
— Avoid short circuits in the electrical system.
— Never reach into the radiator fan. The fan is

temperature-controlled and can turn on
suddenly, even when the ignition is switched
off.
— Never open the hood when there is steam or
coolant escaping from the engine compart-
ment, because there is a risk that you could
be burned. Wait until no steam or coolant is
escaping.
— The cap on the coolant expansion tank must
never be opened when the coolant is hot.
The cooling system is under pressure. There
is a risk of burns
—To protect your face, hands, and arms from
hot steam or coolant, cover the cap with a
thick cloth when opening.
— Do not remove the engine cover under any
circumstances. This increases the risk of
burns.
— Due to the risk of electric shock, never touch
the ignition cable or other components in
the electronic high-voltage ignition system
when the engine is running or is starting.
— If a gear is engaged while the vehicle is sta-
tionary and the engine is running, do not
press the accelerator pedal inadvertently.
Pressing the accelerator pedal will cause the
vehicle to move, and this could result in an
accident.
— If inspections or repairs must be performed
while the engine is running, moving compo-
nents (such as the ribbed belt, generator,
and radiator fan) pose an additional risk.
— Set the parking brake first and select the
“P” (Park) selector lever position.
— Always make sure that no parts of the
body, jewelry, ties, loose clothing, and
long hair can be caught in moving engine
components. Before any work, always re-
move any jewelry and/or ties, tie back long
hair, and make sure all clothing fits close
to the body to reduce the risk of anything
becoming caught in engine components.
— Pay attention to the following warnings list-
ed when work on the fuel system or on the
electrical equipment is required.
— Do not smoke.


1) Depending on the engine and country
221

Checking and Filling


— Never work near open flames.
— Always have a working fire extinguisher
nearby.
— All work on the battery or electrical system
in your vehicle can result in injuries, chemi-
cal burns, accidents, or burns. Because of
this, all work must be performed only by an
authorized Audi dealer or authorized Audi
Service Facility.
— Limit your exposure to exhaust and chemi-
cals to as short a time as possible.

Z\ WARNING
California Proposition 65 Warning:
— Engine exhaust, some of its constituents,
and certain vehicle components contain or
emit chemicals known to the State of Cali-
fornia to cause cancer and birth defects and
reproductive harm. In addition, certain flu-
ids contained in vehicles and certain prod-
ucts of component wear contain or emit
chemicals known to the State of California
to cause cancer and birth defects or other
reproductive harm.
— Battery posts, terminals and related acces-
sories contain lead and lead compounds,
chemicals known to the State of California
to cause cancer and reproductive harms.
Wash hands after handling.



O Note
When filling fluids, be sure not to add any flu-
ids to the wrong reservoirs. Otherwise severe
malfunctions and engine damage will occur.
@ For the sake of the environment
You should regularly check the ground under
your vehicle in order to detect leaks quickly. If
there are visible spots from oil or other fluids,
bring your vehicle to an authorized Audi deal-
er or authorized Audi Service Facility to be
checked.

D_ The & symbol is not available in all countries.
222

Opening and closing the hood
The hood is released from inside the vehicle.

Fig. 158 Unlocked hood: lever
Make sure the wiper arms are not raised up from
the windshield. Otherwise the paint could be
damaged.
Opening the hood
> With the door open, pull the lever >) below
the instrument panel in the direction of the ar-
row > fig. 157.
>» Raise the hood slightly > page 221.
> Press the lever > fig. 158 in the direction of the
arrow. This releases the hooks.
> Open the hood.
Closing the hood
> Push the hood down until you override the
force of the struts.
> Let the hood fall lightly into the latch. Do not
press itin. > AX.
Messages
B Warning! Hood is not locked. Stop vehicle
and check the lock

Checking and Filling

Engine oil
If the engine oil level is too low
If you need to add engine oil, use an oil that is
listed on the sticker. The sticker is located at the
front of the engine compartment > page 223,
fig. 159. When using the engine oil listed on the
sticker, you can adjust the oil level as often as
needed.
If engine oil that meets the recommended speci-
fication is not available, in an emergency you
may add a maximum of 1 quart (1 liter) of
ACEA C3 or API SN engine oil one time until the
next oil change.
For more information on the correct engine oil
for your vehicle, contact an authorized Audi deal-
er or authorized Audi Service Facility. Have the oil
changed by an authorized Audi dealer or author-
ized Service Facility.
G) Tips
Audi recommends using engine oils provided
by Audi Genuine Parts.
Messages
Hiturn off engine. Oil pressure too low
Stop driving and switch the engine off. Check the
engine oil level > page 225.
— If the engine oil level is too low, add engine oil
=> page 225. Only continue driving once the in-
dicator light turns off.
— If the engine oil level is correct and the indica-
tor light still turns on, turn the engine off and
do not continue driving. See an authorized Audi
dealer or authorized Audi Service Facility for as-
sistance.
Applies to: vehicles with oil level warning
2 Please add oil immediately.
Stop driving and switch the engine off. Check the
engine oil level > page 225 and add engine oil
immediately > page 225.
3 Add max. x qt (x l) oil. You can continue
driving
224
Add the amount of oil shown immediately
=> page 225.
EA Please reduce oil level
There is too much oil in the engine and there is a
risk of damaging the catalytic converter or en-
gine. Drive to an authorized Audi dealer or au-
thorized Audi Service Facility immediately to have
engine oil extracted if necessary. Avoid high en-
gine speeds, full acceleration, and heavy engine
loads.
3 Oil level sensor: oil change necessary. Please
contact Service
Fuel has entered the engine oil. This will cause
the engine oil level to rise slowly and the engine
oil quality to decrease. Do not extract engine oil
to reduce the level, because this will increase the
risk of engine damage. Drive to an authorized
Audi dealer or authorized Audi Service Facility im-
mediately to have engine oil extracted.
& Oil level system: malfunction! Please con-
tact Service
The sensor that checks the engine oil level has
malfunctioned. Drive immediately to an author-
ized Audi dealer or authorized Audi Service Facili-
ty to have the malfunction repaired.
2 Oil pressure sensor: malfunction! Please
contact Service
The sensor that checks the engine oil pressure
has malfunctioned. Drive immediately to an au-
thorized Audi dealer or authorized Audi Service
Facility to have the malfunction repaired.
i Please drive to warm up engine
Fuel has entered the engine oil, either due to low
outside temperatures or frequent short drives.
Drive until the engine is warm so that the fuel in
the engine oil will evaporate. Avoid high engine
speeds, full accelerating, and heavy engine loads
when doing this.
G) Tips
The oil pressure warning =} is not an oil level
indicator. Always check the oil level regularly.

8W1012721BC
Checking and Filling


— Maintain enough distance when you are re-
moving the oil drain plug. While doing this,
keep your forearm parallel to the ground to
reduce the risk of hot oil dripping down your
arm.
— Drain the oil into a container designed for
this purpose that is large enough to hold the
full amount of oil in your engine.
— Engine oil is poisonous. Always store out of
reach of children.
— Prolonged contact of used engine oil with
the skin may cause skin damage. Always
wash oil off immediately with soap and wa-
ter to protect your skin.
@) Note
Do not mix any additives with the engine oil.
Additives may cause engine damage that is
not covered by your New Vehicle Limited War-
ranty.

() For the sake of the environment
— Before changing the engine oil, make sure
you can dispose of the used engine oil cor-
rectly.
— Engine oil must always be disposed of cor-
rectly. Do not dump it in the yard, in the for-
est, or in open water, river channels, or sew-
ers.
— Have your used engine oil recycled by bring-
ing it to a used oil collection site or contact
a gas station.
Cooling system
The engine cooling system is filled with a mixture
of purified water and coolant additive at the fac-
tory. This coolant must not be not changed.
The coolant level is monitored using the B indi-
cator light. However, occasionally checking the
coolant level is recommended.
Messages
/_E| Turn off engine and check coolant level. See
owner's manual
The coolant level is too low.
Stop driving and switch the engine off. Check the
coolant level > page 228.
— If the coolant level is too low, add coolant
=> page 228. Only continue driving once the in-
dicator light turns off.
& Coolant temperature: too high. Please let
engine run while vehicle is stationary
Let the engine run at idle for a few minutes to
cool off, until the indicator light turns off.
— If the indicator light does not turn off, do not
continue driving the vehicle. See an authorized
Audi dealer or authorized Audi Service Facility
for assistance.
| Coolant system: malfunction! Please turn
off engine
Do not continue driving, shut the engine off, and
switch the ignition off.
— See an authorized Audi dealer or authorized
Audi Service Facility for assistance.
Coolant additive
The coolant additive is made of anti-freezing and
corrosion protection agents. Only add the follow-
ing coolant additives mixed with distilled water.

Coolant additive Specification


Gl12evo TL774L

The amount of coolant additive that needs to be
mixed with water depends on the climate where
the vehicle will be operated. If the coolant addi-
tive percentage is too low, the coolant can freeze
and damage the engine.


Coolant Freeze protec-
additive tion
Warm min. 40% min. -13 °F
regions max. 45% 25 °C)
Cold min. 50% max. -40 °F
regions max. 55% (-40 °C)

@) Note
— Before the start of winter, have an author-
ized Audi dealer or authorized Audi Service
227
>

Checking and Filling

Facility check if the coolant additive in your
vehicle matches the percentage appropriate
for the climate. This is especially important
when driving in colder climates.
— If the G12evo coolant additive is not availa-
ble in an emergency, do not add any other
additive. You could damage the engine. If
this happens, only use distilled water and
restore the correct mixture ratio with the
specified coolant additive as soon as possi-
ble.
— Only refill with new coolant.
— Radiator sealant must not be mixed with
the coolant.
— You can continue driving if the permitted
G12evo coolant additive was not added.
However, go to an authorized Audi dealer or
authorized Audi Service Facility immediately
to have the coolant replaced to reduce the
risk of engine damage.
— Due to the risk of engine damage, the cool-
ing system should only be refilled by an au-
thorized Audi dealer or authorized Audi
Service Facility. An authorized Audi dealer or
authorized Audi Service Facility can also pro-
vide you with important information about
the recommended coolant additive.
(Gitta diet lis

RAZ-0540,



Fig. 161 Engine compartment - Coolant expansion tank:
@ cover with release button; @) markings
Observe the safety precautions > page 221, Gen-
eral information.
Checking the coolant level
> Park the vehicle on a level surface.
> Switch the ignition off.
> Open the hood > page 222.
228
The coolant expansion tank for some engines is
located in the water drip tray under a cover. If
necessary, remove the cover that is located under
the windshield wiper on the front passenger's
side.
> Check the coolant level in the coolant expan-
sion tank > page 223, fig. 159 using the outer
markings (2) > fig. 161. The coolant level must
be between the markings (2) when the engine is
cold. When the engine is warm it can be slight-
ly above the upper marking.
» Applies to: vehicles with 6-cylinder engine:
There is a float located in the coolant expansion
tank. Read the coolant level using the coolant
level float. When the engine is cold, the float
must be located between the MIN marking and
the edge of the filler opening on the coolant ex-
pansion tank.
> When you add coolant to the expansion tank,
please refer to > page 227, Cooling system.
Adding coolant
Requirement: there must be a residual amount of
coolant in the expansion tank >@).
If you must add coolant, use a mixture of water
and coolant additive. Audi recommends mixing
the coolant additive with distilled water.
> Allow the engine to cool.
> Place a large, thick towel on the coolant expan-
sion tank cap.
> Push the release button @ > fig. 161 on the
cap and carefully turn it to the left until you
feel resistance > /\.
> Push the release button again and remove the
cap completely.
» Add coolant in the correct mixture ratio
=> page 227 up to the MAX marking. Or, in
vehicles with a 6-cylinder gasoline engine, the
float must be located between the MIN mark-
ing and the edge of the filler opening on the
coolant expansion tank.
> Make sure that the fluid level remains stable.
Add more coolant if necessary.
> Vehicles with 6-cylinder engine: if necessary,
press the float into the coolant expansion tank
using the cover.
> Turn the cap to the right to tighten it until you
feel resistance a second time.