2021 AUDI A4 check engine

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

8W1012721BC

Drive select

refer to Audi drive select.............0. 110
Drive system... 1.2... cee ee eee 101
AUdi drive Select sais s & news < ¢ says & 3 ve 110
Drive system (message) ........... eee eee 103
Driving down hills............ 00.000 eee 107
DFIVIMGJPFOGFAMM:. « wnaceos % 0 spesine 6 & axonese on mune 137
Driving through water...............0.. 108
Driving CIM: « cescues & a ssanees vw ones vv orn a 8 a 16
Driving tips
Driving through water...............-- 108
Efficient driving...............-00000- 102
Offroad GriWitG cows sc caws se pean es ewan 108
Uphill and downhill................00. 107
Driving:up Wills: « ssc s 2 wave 6 o sree wv sew 107
Dust filter
refer to Pollutant filter................. 90
DYMAMMIGIStEORIAG, cxsieos ov secre © « soneers © ¥ soaser Lill
E
EFimailss os i: cwcsan oa ncewios ow sesnin @ ononans wa wretnon 4 T/1,
Settings............. 0.00. e eee eee ee 171
EDL
refer to Electronic Differential Lock...... 113
EDR
refer to Event Data Recorder (EDR)...... 277
Efficiency ASSISE: s wes » x ows & a ews 8 6 ow 128
Predictive :comtro lin: « cxvim x 0 sensawe oo swowane 133
Electrical system ........ 2... cee eee eee 230
Electromechanical parking brake......... 106
Electronic Differential Lock.............. 113
Electronic immobilizer................5-. 38
Electronic Stabilization Control........... 113
Embedded SIM card............--.00005 174
Emergency assistance...............00. 261
Emergency braking function............. 106
Emergency call... «ccc. 2 mwa ve ewe 169,178
Emergency flashers..............--0000- 53
Emergency modéw Emergency operation
DOONS eves ov comme a a same ao omnes vv om x
Fuel filler door
Luggage compartment lid............... 43
Panoramic glass roof................005 47
Sliding/tilting sunroof...............00. 46
Emissions control system..............- 220
EnergyCOnsSUMErSi. & & sive a 2 wasn ao mare oes 16
Energy management...............0005 102
Engine
Breakingiin « sss c= cee = 2 aves ov ere a ee 101
Coolant..... 0.0... cece eee eee ee eee 227
EMe@ngenty StOpis « = ewes 5 2 sees ¢ 2 wees Fs me 95
JUMp'StARtING & vesi% « 6 war % 6 senens & ewes 268
Start/Stop system ......... 0. eee ee eee 102
Starting/Stopping:: « « seme os ews 5 wen s « 95
Engine compartment
Opening and closing the hood.......... 222
OVERVIEW cscssiic xo ciueins xo anette 6H atetaaie © ooetts 223
Safety precautions..................0. 221
Engine oil
AGQING = ex ¢ = seem « = ress « ¢ ee § pe 224
GhANGING sis «sess ss rena « waver 2» omen © 226
Checking oil level.............00-.000- 224
CONSUMPtIONs « 2 was s 2 ene x eee 5 oe 224
Indicator light « sss + «owes sw ssweenn ow vase 224
Replacement interval................. 233
Temperature display............0.e00e 15
Engine sound
Audi driveselect’s osx. < + sx » x come © ee 110
Engine Start/Stop mode
refer to Start/Stop system............. 102
Engine startsystem sce 3 5 seu o 9 was o 9 som 96
Engine stop
refer to Start/Stop system............. 102
Entry/exit. IQhtingie: + scsi as essen & © wonvme a v6 53
Entryiassistanee:: 2 coca 2s acim os eee 2 o were 65
also refer to Exit assistance............. 65
Environment
Unleaded gasoline.................00. 217
ESC
refer to Electronic Stabilization Control... 113
ESC Offroad... 2.1... eee eee ee 114
ESC Sport........... 000.000.0000 0000- 114
eSIM
refer to Embedded SIM card............ 174
Event Data Recorder (EDR).............. 277
Exit assistance .... 0.2... 0.00... e eee eee 65
Exit warning ...... 0.66... e ee ee eee eee 148
Exteriomantenna «cise oo srerw wane © aecete 165
Exterior Lighting’: = = sce «= seus © x cere = 4 seus 51
291