check engine AUDI A4 2021 Owner´s Manual

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.

8W1012721BC
Checking and Filling

Coolant loss usually indicates that there is a leak.
Immediately drive your vehicle to an authorized
Audi dealer or authorized Audi Service Facility
and have the cooling system inspected. If the
cooling system is not leaking, coolant loss can re-
sult from the coolant boiling due overheating
and then being forced out of the cooling system.

A WARNING
— The engine compartment in any vehicle is a
potentially dangerous area. Stop the engine,
switch the ignition off, and allow the engine
to cool before working in the engine com-
partment. Always follow the information
found in > page 221, General information.
— Never open the hood if you can see or hear
steam or coolant escaping from the engine
compartment. This increases the risk of
burns. The cooling system is under pressure.
When you no longer see or hear steam or
coolant escaping, you may open the engine
compartment with caution.
— When working in the engine compartment,
remember that the radiator fan can switch
on even if the ignition is switched off, which
increases the risk of injury.
— Coolant additive and coolant can be danger-
ous to your health. For this reason, store the
coolant in the original container and away
from children. There is a risk of poisoning.

® Note
Do not continue driving if the coolant expan-
sion tank is empty. Do not add any coolant,
because air could enter the cooling system
and damage the engine. See an authorized
Audi dealer or authorized Audi Service Facility
for assistance.
Brake fluid

BFV-0229]


Fig. 162 Engine compartment: cap on brake fluid reservoir
Observe the safety precautions > page 221, Gen-
eral information.
Checking the brake fluid level
The brake fluid reservoir is located under a cover
on the driver’s side.
> Lift the cover > page 223, fig. 159 at both
openings and remove it.
> Read the brake fluid level on the brake fluid res-
ervoir > page 223, fig. 159. The brake fluid lev-
el must be between the MIN and MAX markings
of.
The brake fluid level is monitored automatically.
Messages
EG / @ Brakes: stop vehicle and check brake
fluid level
Stop the vehicle and check the brake fluid level.
See an authorized Audi dealer or authorized Audi
Service Facility for assistance.
Changing the brake fluid
Brake fluid should be changed at regular inter-
vals. Have the brake fluid changed by an author-
ized Audi dealer or authorized Audi Service Facili-
ty. The authorized Audi dealer or authorized Audi
Service Facility will inform you of the replace-
ment intervals.

Z\ WARNING
— If the brake fluid level is below the MIN
marking, it can impair the braking effect and
driving safety, which increase the risk of an

229

Checking and Filling


accident. Do not continue driving. See an au-
thorized Audi dealer or authorized Audi
Service Facility for assistance.
— If the brake fluid is old, bubbles may form in
the brake system during heavy braking. This
could impair braking performance and driv-
ing safety, which increases the risk of an ac-
cident.
— The brake fluid in your vehicle must meet
the standard VW 501 14 and is available at
an authorized Audi dealer or authorized
Audi Service Facility. If this brake fluid is not
available, another high-grade brake fluid of
equivalent quality may be used, and it must
meet the U.S. Federal Motor Vehicle Stand-
ard (FMVSS) 116 DOT 4, Class 6.

Switch off all electrical equipment that is not
needed. If necessary, some equipment will be
switched off automatically. Vehicle functions or
driving stability may be limited. Drive to an au-
thorized Audi dealer or authorized Audi Service
Facility immediately.
z= Electrical system: low battery charge. Bat-
tery
will be charged while driving
The starting ability may be impaired.
If this message turns off after a little while, the
vehicle battery has charged enough while driving.
If this message does not turn off, drive immedi-
ately to an authorized Audi dealer or authorized
Audi Service Facility.

@) Note
— If the brake fluid level is above the MAX
marking, brake fluid may leak out over the
edge of the reservoir and result in damage
to the vehicle.
— Do not allow any brake fluid to come into
contact with the vehicle paint, because it
will corrode the paint.
Electrical system
If the = / B or = indicator light turns on,
there is a malfunction in the power supply, the
battery, or the vehicle electrical system.
mz / B Electrical system: malfunction! Safely
stop vehicle
Do not continue driving and switch the ignition
off > A\. See an authorized Audi dealer or author-
ized Audi Service Facility for assistance.
= Electrical system: malfunction! Restart not
possible. Please contact Service
If you switch the ignition off, you will not be able
to restart the vehicle. Vehicle functions or driving
stability may be limited. Drive to an authorized
Audi dealer or authorized Audi Service Facility im-
mediately.
= Electrical system: malfunction! Please con-
tact Service
230
ZA\ WARNING
When there is an electrical system malfunc-
tion, vehicle functions may not work and driv-
ing stability may be limited, which increases
the risk of an accident. Do not continue driv-
ing and switch the ignition off. See an author-
ized Audi dealer or authorized Audi Service Fa-
cility for assistance.

Battery
ela lame (Tem eeecela)
Because of the complex power supply, all work on
batteries such as disconnecting, replacing, etc.,
should only be performed by an authorized Audi
dealer or authorized Audi Service Facility > A\.
Multiple batteries with different technologies
may be installed in your vehicle:
— Vehicle battery (for example, for starting the
engine, basic power supply) > page 231, 12
Volt vehicle battery or > page 232, Other bat-
tery types
— Auxiliary battery (for example, for recuperation
or optional equipment) > page 232, Other bat-
tery types
Not running the vehicle for long periods of
time
The battery will gradually drain if the vehicle
does not run for long periods of time. To ensure >

8W1012721BC
Checking and Filling

that the vehicle can still be started, the electrical
equipment will be limited or switched off. Some
convenience functions, such as interior lighting
or power seat adjustment, may not be available
under certain circumstances. The convenience
functions will be available again when you start
the
engine.
Even when electrical equipment is switched off,
the equipment can still drain the battery if the
vehicle is not driven for Long periods of time.
Deep draining results in a chemical reaction that
destroys the inside of the battery. The battery
must be charged every month to prevent this
= page 232. Contact an authorized Audi dealer or
authorized Audi Service Facility for more infor-
mation.
Winter operation
Cold weather places an especially high load on
the 12 Volt vehicle battery. Have the battery
checked by an authorized Audi dealer or author-
ized Audi Service Facility before cold weather be-
gins.
so that it will not be destroyed by “freezing”
=> page 232, Charging the 12 Volt vehicle
battery.
— There are electrical components under the
cargo floor behind a trim panel that warm
up during operation. To reduce the risk of
the components overheating, do not store
objects such as blankets under the cargo
floor. If the components overheat, they will
switch off temporarily. This will be indicated
by a message that will be displayed in the
instrument cluster until the temperature re-
turns to normal.
12 Volt vehicle battery
Explanation of warnings:
Always wear eye protection.

forbidden.

ZA WARNING
— 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.
— Never connect a charging cable or jump
start cable directly to the 12 Volt vehicle
battery. Only use the connections in the en-
gine compartment > page 232.

ZA WARNING
California Proposition 65 Warning:
— 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.

@) Note
— If the vehicle will be parked for long periods
of time, protect the battery against the cold
A highly explosive mixture of gases can
form when charging batteries.

Always keep children away from battery
acid and the battery.
Battery acid is highly corrosive. Always
wear protective gloves and eye protection.
® Fire, sparks, open flame, and smoking are

@/ | Always follow the instructions in the oper-
(QO | ating manual.

@) For the sake of the environment

“© % Lead-acid batteries must be disposed of
using methods that will not harm the environ-
ment. Do not dispose of them in household
trash. They contain harmful substances, such
as sulfuric acid and lead, and also recyclable
raw materials. Contact an authorized Audi
dealer or authorized Audi Service Facility for
more information.
231

Checking and Filling

Other battery types
Explanation of warnings:


Fire, sparks, open flame, and smoking are
& forbidden.
Always keep children away from battery
@) acid and the battery.


@/ | Always follow the instructions in the oper-
fQ) | ating manual.

ZA\ WARNING
All work on the batteries must only be per-
formed by an authorized Audi dealer or au-
thorized Audi Service Facility.
— Gases that escape from these different bat-
tery types can be poisonous or flammable.
— The contents of these battery types can be
corrosive. If any battery contents come into
contact with the skin, flush the affected
area for at least 15 minutes with clean wa-
ter. Then wash the affected area with soap.
Have the affected area examined by a medi-
cal professional.
@) Note
Components must not be connected to the
battery terminals and wires on these battery
types because this increases the risk of dam-
age, for example due to overvoltage.

@ For the sake of the environment
“These types of batteries must be dis-
posed of using methods that will not harm
the environment. Do not dispose of them in
household trash. They contain harmful sub-
stances and recyclable raw materials. Contact
an authorized Audi dealer or authorized Audi
Service Facility for more information.
232
rging the 12 Volt vehicle battery

Fig. 163 Engine compartment: connectors for a charger or
jump start cables
Observe the safety precautions > page 221, Gen-
eral information, > /\ in Battery general infor-
mation on page 231 and > /\.
Requirement: only use chargers with a maximum
charging current of 14.8 volts. The battery ca-
bles remain connected.
The charging cable connections are located in the
motor compartment. The ground point ©) is al-
ways located on the vehicle body.
> Switch off the ignition and all electrical equip-
ment.
> Open the hood > page 222.
> Press the release lever on the positive terminal
and fold the cover upward > fig. 163.
> Clamp the charger terminal clamps to the jump
start pins according to the instructions. (Hex
head bolt under a cover @), ground point on the
vehicle body ©)).
> Insert the power cable for the charging device
into the socket and switch the device on.
>» At the end of the charging process, switch the
charger off and pull the power cable out of the
socket.
> Remove the charging device terminal clamps.
> Close the cover on the positive terminal.
> Close the hood > page 222.

ZA WARNING
— Never connect a charging cable or jump
start cable directly to the 12 Volt vehicle
battery. Only use the connections in the en-
gine compartment > page 232. >

8W1012721BC
Checking and Filling


— A highly explosive mixture of gases can form
when charging batteries. Only charge the
battery in well-ventilated areas.
— A drained battery can freeze at tempera-
tures around 32 °F (0 °C). Do not charge or
use a frozen or thawed battery. If ice forms,
the battery housing can crack and battery
electrolyte can leak out, which increases the
risk of an explosion and chemical burns.
Contact an authorized Audi dealer or author-
ized Audi Service Facility for more informa-
tion.
— Do not connect or disconnect the charging
cable while charging because this increases


the risk of an explosion.

@) Tips
Read all of the manufacturer's instructions
for the charger before charging the battery.
Windshield washer
system

B8W-0125



Fig. 164 Engine compartment: washer fluid reservoir cap
Observe the safety precautions > page 221, Gen-
eral information.
The windshield washer reservoir © contains the
cleaning solution for the windshield/rear win-
dow* and the headlight washer system*
> fig. 164, > page 223. The reservoir capacity
can be found in > page 287.
To reduce the risk of lime scale deposits on the
spray nozzles, use clean water with low amounts
of calcium. Always add window cleaner to the wa-
ter. When the outside temperatures are cold, an
anti-freezing agent should be added to the water
so that it does not freeze.
Messages
3 Please add washer fluid
Fill the washer fluid for the windshield washer
system and the headlight washer system* when
the ignition is switched off.
@) Note
— The concentration of anti-freezing agent
must be adjusted to the vehicle operating
conditions and the climate. A concentration
that is too high can lead to vehicle damage.
— Never add radiator anti-freeze or other addi-
tives to the washer fluid.
— Do not use a glass cleaner that contains
paint solvents, because this could damage
the paint.
Service interval display
The service interval display detects when your ve-
hicle is due for service.
The service interval display works in two stages:
— Inspection or oil change reminder: after driv-
ing acertain distance, a message appears in the
instrument cluster display each time the igni-
tion is switched on or off. The remaining dis-
tance or time is displayed briefly.
— Inspection or oil change due: if your vehicle
has reached an inspection or oil change interval
or both intervals at the same time, the mes-
sage Inspection due! or Oil change due! or Oil
change and inspection due! appears briefly af-
ter switching the ignition on or off.
Checking service intervals
You can check the remaining distance or time un-
til the next oil change or next inspection in the
Infotainment system.
Applies to MMI: Select on the home screen: VE-
HICLE > Settings & Service > Service intervals.
Resetting the indicator
An authorized Audi dealer or authorized Audi
Service Facility will reset the service interval dis-
play after performing service.
233
>

Checking and Filling

If you have changed the oil yourself, you must re-
set the oil change interval.
Applies to: MMI: To reset the display, select on
the home screen: VEHICLE > Settings & Service
> Service intervals.
@) Note
— Only reset the oil change indicator if the oil
was changed.
— Following the service intervals is critical to
maintaining the service life and value of
your vehicle, especially the engine. Even if
the mileage on the vehicle is low, do not ex-
ceed the time for the next service.
234

Emergency assistance

@) Note
The compressor must be switched off after six
minutes at the most to reduce the risk of
overheating. Let the compressor cool down
for several minutes before using it again.
Jump starting
You should only perform the steps that follow if
you have the necessary tools and technical ex-
pertise.
If the engine does not start because the vehicle
battery is drained, you can jump start your vehi-
cle using another vehicle. Jump start cables are
needed to do this.
Both vehicle batteries must have 12 V nominal
voltage. The voltage capacity (Ah) of the vehicle
battery that is giving power must not be less
than the capacity of the drained vehicle battery.
Jump start cable
Only use a jump start cable with a large enough
diameter. Note the manufacturer's specifica-
tions.
Only use a jump start cable with insulated termi-
nal clamps.
Positive cable - usually red.
Negative cable - usually black.

ZA\ WARNING
— A drained battery can freeze at tempera-
tures around 32 °F (0 °C). If the vehicle bat-
tery is frozen, it must be thawed before con-
necting the jump start cables. If it is not,
the risk of an explosion and chemical burns
increases. After jump starting the vehicle,
drive to an authorized Audi dealer or author-
ized Audi Service Facility immediately to
have the vehicle battery checked.
— Read the warnings when working in the en-
gine compartment > page 221.
— Handling the jump start cables incorrectly
may cause the vehicle battery to explode
and lead to serious injuries.

268
@) Note
Jump start cables can cause considerable
damage to the vehicle electrical system if
they are connected incorrectly.
@) Tips
— There must be no contact between the
vehicles, or else voltage could flow when
connecting the positive terminal and drain
the vehicle battery of the vehicle providing
the jump start.
— The drained vehicle battery must be con-
nected correctly to the electrical system.
— Switch off electrical equipment that is not
needed.

Both jump start cables must be connected in the
correct order.

Fig. 179 Engine compartment: connectors for jump start
cables or a charger



Fig. 180 Engine compartment: connectors for jump start
cables or a charger
The jump start cable connections are located in
the engine compartment.
Follow the information about the vehicle battery
=> page 230. >

8W1012721BC
Fuses and bulbs

@) Note
If a new fuse burns out again shortly after you
have installed it, have the electrical system
checked as soon as possible by an authorized
Audi dealer or authorized Audi Service Facili-
t y.
G@) Tips
— The following table does not list fuse loca-
tions that are not used.
— Some of the equipment listed in the follow-
ing tables applies only to certain model ver-
sions or certain optional equipment.

Fig. 184 Driver's footwell (left-hand drive vehicle): fuse
panel with plastic clip
3
=f
= & a

x
Ss $ 2 8

Fig. 185 Front passenger's footwell (right-hand drive vehi-
cle): fuse panel with plastic clip


f ) (brown)
No. | Equipment

1 | Catalytic converter heating

2 | Engine components

Exhaust doors, fuel injectors, radiator in-
let, crankcase housing heating

Vacuum pump, hot water pump, NOx sen-
4 |sor, particulate sensor, biodiesel sensor,
exhaust doors

Brake light sensor

6 | Engine valves, camshaft adjustment

Heated oxygen sensors, mass airflow sen-
sor, water pump

Water pump, high pressure pump, high
8 |pressure regulator valve, temperature
valve, engine mount

Hot water pump, motor relay, 48 V drive-
train generator, 48 V water pump

10 | Oil pressure sensor, oil temperature sensor

Clutch position sensor, 48 V drivetrain
11 |generator, water pump, 12 V drivetrain
generator

12 | Engine valves, engine mount


13 | Engine cooling

273