2021 AUDI A4 check engine light

8W1012721BC
Quick access

@9 Center armrest with storage com-
partment. Depending on vehicle
equipment, it may have:



— Audi music interface .......... 202
—Audi phone box ............... 164
— Starting the engine if there is a
MALFUMERION since oo sxosoue x 2 seems ss 95
@) Electromechanical parking brake
BUGGOT sieves so cman « 2 ewes 2s men 2 106
@) Selector lever (automatic transmis-
SIOM) seo so neon & v Howe & eRe Fa 97
@3 Storage compartment .......... 83
@ [START ENGINE STOP]button .... 95
@3) Audi music interface ............ 202
@@ Steering wheel adjustment ...... 66
@) Lever for:
— Cruise control system ......... 127
— Audi adaptive cruise control .... 130
® Button for switching the head-up
display on and off, adjusting the
height ........ 2... cee eee eee 25
@ Instrument illumination ......... 55
60) Connection port for the On Board
Diagnostic System (OBD) ........ 277
@) Headlight control switch ........ 51
@ Hood release ...............0-. 222
63 All-weather lights button ........ 51
@4 Luggage compartment lid button . 40
@5) Exterior mirror adjustment ...... 55
68 Buttons for:
— Power windows ...........00. 45
—Child safety lock .............. 44
@) Tips
Some the equipment listed here is only instal-
led in certain models or is available as an op-
tion.
Indicator lights overview
The indicator lights in the instrument cluster
blink or turn on. They indicate functions or mal-
functions. Some warning and indicator lights
turn on when you switch the ignition on and must
turn off when the drive system is switched on or
while driving.
With some indicator lights, messages may ap-
pear and warning signals may sound. The indica-
tor lights and messages may be covered by other
displays. To show them again, select the second
tab for messages with the multifunction steering
wheel > page 13.
Some indicator lights in the display can display in
several colors.
OMe eee any
If the wA or N indicator light turns on, check
the message in the instrument cluster.
The following indicator lights may be available,
depending on the vehicle equipment:

Red indicator lights
Central indicator light
=> page 7,
Instrument cluster
=>page 12
















Cooling system
> page 14,
=> page 227,
=> page 227
Safety belt
=> page 70
Transmission
= page 100
Drive system
= page 102,
Electrical system
=> page 230
Brake system
=>page
105,
=>page 229,
Electromechanical parking brake
=> page 107 >

Driving

“N” (Neutral) gear
In the “N” gear, power is not transmitted to the
driving wheels. Use the “N” gear in a car wash
(with conveyor belts), for example.
If you unintentionally select “N” while driving
(faster than 1 mph (2 km/h)), you can also shift
back to “D” without pressing the brake pedal.
For safety reasons, the vehicle cannot be locked
when the transmission is in the "N” gear.
“Pp” (Park) gear
Requirement: the ignition must be switched on.
The vehicle is secured from rolling away by the
parking lock when in the “P” gear.
— Bring the vehicle to a full stop and press the
brake pedal.
— Press the “P” button @) on the selector lever.
— The “P” next to the selector lever will light up.
“P” engages automatically if you switch the en-
gine off while the “D” or “R” gear is selected. If
you switch the engine off in “N”, “P” will engage
automatically after approximately 30 minutes.
If you want to switch from “P” to “D” or “R”, the
engine must be running.
If you cannot shift out of “P”, for example be-
cause the vehicle has no power, you may need to
use the emergency release for the parking lock
=> page 100.
Selecting a driving program
Various driving programs can be selected when in
the “D” gear. The programs influence when the
transmission shifts and how the accelerator ped-
al responds.
The selected driving program is displayed in the
instrument cluster.
—D (Drive): normal driving mode
— S (Sport): sporty driving mode
If you select the Dynamic mode in Audi drive se-
lect*, the “S” driving program will be activated.
When the ignition is switched off, the driving pro-
gram may be reset to “D”.
98
To switch between the current driving program
and “S”, push the selector lever toward the rear.

ZA WARNING
— Before you start driving, check if the label
for the desired selector lever position next
to the selector lever is lit up.
— Secure the vehicle against rolling before ex-
iting the vehicle > page 96.
— Power is still transmitted to the wheels
when the engine is running at idle. To pre-
vent the vehicle from “creeping”, you must
keep your foot on the brake in all selector
lever positions (except "P" and "N") when
the engine is running.
— To reduce the risk of an accident, do not
press the accelerator pedal when changing
gears if the vehicle is stationary and the en-
gine is running.
— Never select the “R" or "P” gears while driv-
ing. Doing so could cause an accident.
— The vehicle can roll even if the ignition is
switched off.

@) Tips
If you shift between “D” and “R” within one
second, you do not need to press the brake
pedal. This makes it possible to “rock” if it is
stuck, for example.

8W1012721BC
Driving

Switching the Start/Stop system off and on
The )* button is located above the selector lev-
er in the center console. The LED in the button
turns on when the function is switched off.
> Press (A)°* to switch the system on or off.
If you switch the system off during a Stop phase,
the engine will start again automatically.
Basic requirements
— The driver’s door and the hood must be closed
and the driver’s safety belt must be fastened.
—"P","N", or "D" must be engaged.
—The steering wheel must not be turned far in ei-
ther direction.
— The vehicle must have driven faster than 2 mph
(3 km/h) since the last time it stopped.
— The vehicle is not in trailer mode.
@ Note
Always switch the Start/Stop system off when
driving through water > page 103.
@ Tips
— Depending on the driving situation, the en-
gine may already stop when coasting before
the vehicle has come to a complete stop.
— If you select the "D" position after shifting
into reverse, the vehicle must be driven fast-
er than 6 mph (10 km/h) in order for the
Start/Stop system to become active again.
This makes it possible to maneuver without
stopping the engine.
Stopping and starting the engine
Applies to: vehicles with Start/Stop system
> Press and hold the brake pedal until the vehicle
has stopped. The @] indicator light appears in
the instrument cluster once the engine stops
automatically.
> The engine starts again when you remove your
foot from the brake pedal. The indicator light
turns off.
If the parking brake is set, the engine will only
start again when the accelerator pedal is pressed.
@) Tips
— Press the brake pedal during a Stop phase
to keep the vehicle from rolling.
— The ignition will turn off if you press the
START ENGINE STOP] button during a Stop


phase.
— If you leave the vehicle briefly during a Stop
phase and then enter again, the driver's
door must be closed and the safety belt
must be fastened in order for the engine to
be able to restart.
— You can control if the engine will stop or not
by reducing or increasing the amount of
force you use to press the brake pedal. For
example, if you only lightly press on the
brake pedal in stop-and-go traffic or when
turning, the engine will not switch off when
the vehicle is stationary. If you press the
brake pedal harder, the engine will switch
off.
Starting and stopping the engine automat-
ically
Applies to: vehicles with Start/Stop system
The system checks if certain conditions are met
before and during the Stop phase, and deter-
mines if the engine stops and how long it re-
mains stopped. For example, if power usage is
high, the engine will not be stopped. Along with
other conditions, the following factors influence
the automatic engine start or stop:
— Environmental conditions (slopes, inclines, ele-
vation, temperature)
— Battery (charge status, temperature, power us-
age)
— Engine temperature
— Assist systems
— Driving behavior
Depending on the engine, the Gy indicator light
may appear if the engine is not stopped.
Applies to: vehicles with Start/Stop system
Drive system: please start the vehicle manually >
103

8W1012721BC
Driving


ZA WARNING
— Only apply the brakes for the purpose of
cleaning the brake system when road and
traffic conditions permit. You must not en-
danger other road users and increase the
risk of an accident.
— Due to the risk of injury, only have an au-
thorized Audi dealer or authorized Audi
Service Facility work on the brake system.
Incorrect repairs could impair the function.
— Never let the vehicle roll while the engine is
stopped because this increases the risk of an
accident.
— During automatic braking maneuvers, the
brake pedal may move downward automati-
cally. To reduce the risk of injury, do not
place your foot under the brake pedal.
@) Note
— Never let the brakes “rub” by pressing the
pedal lightly when braking is not actually
necessary. This can cause the brakes to over-
heat and increases braking distance and
causes wear.
— Observe the important information for driv-
ing downhill > page 107. This especially ap-
plies when towing a trailer.
@) Tips
— In vehicles with an electromechanical brake
booster, the resistance in the brake pedal
may vary depending on the driving situation
(such as if driver assistance system are ac-
tive).
— If you retrofit your vehicle with a front spoil-
er, wheel covers or similar items, make sure
that the air flow to the brakes is not ob-
structed. Otherwise the brake system can
overheat.

— Also refer to the information about brake
fluid > page 229.
Ga 7 @ Brakes: malfunction! Stop vehicle
safely
There is a malfunction in the brake system. If
[S/ Bana fA also turn on, there is a malfunc-
tion in the ABS, ESC, and braking distribution. If
the brake booster is not working, you have to use
much more force when braking the vehicle.
Do not continue driving. See an authorized Audi
dealer or authorized Audi Service Facility for as-
sistance. Read and follow the other safety pre-
cautions > A\.
Hie / © Brake pads: wear limit reached. You
can continue driving. Please contact Service
The brake pads are worn. Drive to an authorized
Audi dealer or authorized Audi Service Facility as
soon as possible to have the malfunction correct-
ed.
Brake booster: limited functionality. You can
continue driving. Please contact Service
There is a brake booster malfunction. The brake
booster is available, but its effectiveness is re-
duced. The braking performance may be different
compared to the usual performance. Drive to an
authorized Audi dealer or authorized Audi Service
Facility immediately to have the malfunction cor-
rected.
Brake booster: deactivated. See owner's manual
The brake booster remains active for a brief peri-
od of time after switching off the ignition. Secure
the vehicle against rolling > page 96.
Other indicator lights
When you switch the ignition on, the EG i @
indicator light turns on briefly to check the func-
tion. If the indicator light does not turn on, there
is a system malfunction.
file / © stays on, there is a malfunction in
the brake system.
@- A high load was placed on the brakes from
driving downhill for a long period of time. Follow
the instructions in the message to utilize the en-
gine braking effect and to relieve the brakes.

Z\ WARNING
If a malfunction occurs in the ABS, ESC, and
braking distribution, interventions that >

105

Driving

Offroad driving
Applies to: allroad
Your vehicle is not an offroad vehicle. Note the
following points when driving offroad:
— Drive slowly and carefully.
—To reduce the risk of underbody damage, pay
attention to the vehicle's ground clearance and
drive across raised areas of the ground with the
wheels on one side of the vehicle, instead of al-
lowing the center of the vehicle to pass over the
raised areas.
— To reduce the risk of becoming stuck, drive
through sandy or swampy areas at a steady
speed and without stopping, if possible.
If necessary, use the following functions:
— Audi drive select* Offroad mode > page 110
— Hill hold assist* > page 108
— Limit ESC > page 114

ZA WARNING
Only drive in terrain that is suitable for the ve-
hicle and your driving ability.

@ For the sake of the environment
Avoid actions that are damaging to the envi-
ronment. Show respect for the natural envi-
ronment and remain on marked routes.
G) Tips
Clean your vehicle after driving offroad. Dirt
and stones falling off your vehicle can affect
other road users.
Driving through water
If you must drive through water, follow these in-
structions:
— Check the stability of the ground, the current,
and the water depth. If the ground is unstable,
there is a strong current, or there are waves,
the water must only reach up to the lower edge
of the body at the most.
— Deactivate the Start/Stop system*.
— Drive carefully and no faster than at walking
speeds to prevent the front of the vehicle from
108
creating waves, because they could splash
above the lower edge of the body. Oncoming
vehicles could also create waves.
— Do not stop the vehicle while in the water.
— Drive in reverse.
— Do not turn the engine off.

ZA WARNING
After driving through water, press the brake
pedal carefully to dry the brakes so that the
full braking effect will be restored.
@) Note
Vehicle components such as the engine, drive
system, suspension, or electrical system can
be severely damaged by driving through wa-
ter
Gi) Tips
If possible, avoid driving through salt water
because it increases the risk of corrosion. Use
fresh water to clean any vehicle components
that come into contact with salt water.
Hill descent assist
Applies to: vehicles with hill hold assist


The “2 button is located above the selector lever
in the center console. It lights up when the sys-
tem is turned on.
Hill descent assist can assist you when driving
down hills by maintaining a constant vehicle
speed by automatically braking all four wheels.
You can adjust the speed using the accelerator
and brake pedals. The regulation depends on the
hill and the vehicle speed.
> Switching on: press “2.
> Switching off: press “2 again.
Active regulation
Regulation begins shortly after you start driving
and is possible at speeds up to approximately 19
mph (30 km/h) and on hills that have an approxi-
mately 6-60% grade. If these conditions are met,
regulation will be activated and the indicator
light will turn on.

8W1012721BC
Driving dynamic

Suspension
CET tes un) Led
Applies to: vehicles with suspension control
The adaptive dampers are an electronically-con-
trolled damping system. The firmness of the sus-
pension will adapt to the driving conditions and
the driving situation. The settings depend on the
selected Audi drive select* mode.
Ground clearance
The vehicle height and clearance can be influ-
enced by the following factors:
— Change in temperature
— Change in load

Z\ WARNING
To reduce the risk of injury, make sure no one
gets pinched when the vehicle level is chang-
ing, for example when cleaning the under-
body or the wheel housings.
@) Note
Always make sure there is enough clearance
above and below the vehicle. This is especially
important for entrances with height restric-
tions, for example, before driving into under-
ground garages. You could also scrape the
ground when driving over the edges of curbs
or on steep ramps, which could damage your
vehicle.

Werle
8 | Suspension: malfunction! You can continue
driving
There is a malfunction. See an authorized Audi
dealer or authorized Audi Service Facility for as-
sistance.
Steering
Electromechanical steering supports the driver's
steering movements by electronically adapting
the power steering depending on the vehicle
speed. The settings depend on the selected Audi
drive select* mode.
Dynamic steering
Applies
to: vehicles with dynamic steering
The driving dynamic and driving stability are in-
creased by the steering ratio based on the speed.
At reduced speeds, steering is direct in order to
provide agile steering behavior and keep the
steering effort as minimal as possible when the
driver is maneuvering the vehicle. This sets the
steering to be less sensitive at higher speeds in
order to provide improved vehicle control.
a Steering: malfunction! Please stop vehicle
The power steering may have failed. Adapt your
driving style immediately to compensate for the
fact that it may be more difficult to turn the
steering wheel, and stop your vehicle in a safe lo-
cation as soon as possible. Secure the vehicle
against rolling before exiting the vehicle
=> page 96. Do not continue driving. See an au-
thorized Audi dealer or authorized Audi Service
Facility for assistance.
|e —e| Steering: malfunction! Please stop vehicle
There is a malfunction in the electronic steering
lock. You cannot turn the ignition on. Secure the
vehicle against rolling before exiting the vehicle
= page 96. Do not tow your vehicle because it
cannot be steered. See an authorized Audi dealer
or authorized Audi Service Facility for assistance.
a Steering: malfunction! You can continue
driving
There is a malfunction in the steering system.
Steering may be more difficult or more sensitive.
Adapt your driving style. Have the steering sys-
tem checked immediately by an authorized Audi
dealer or authorized Audi Service Facility. Please
note that the red indicator light may turn on af-
ter restarting the engine. Do not continue driving
if it does.
l@-| Steering lock: malfunction! Please contact
Service
111
>

8W1012721BC
Trailer towing

Trailer towing
Driving with a trailer
eT e e eeu)
Your vehicle is primarily intended for transport-
ing people and luggage. However, if you drive
with a trailer, follow the technical requirements,
the operation and driving tips, and the legal reg-
ulations.
Driving with a trailer affects the vehicle's energy
usage, performance, and wear. It also requires
higher concentration from the driver.

Z\ WARNING
Do not transport any people in a trailer due to
the risk of fatal injury.
Technical requirements
Trailer hitch

Only use a trailer hitch with a removable ball
hitch mount and ball hitch. The trailer hitch must
be permitted for the vehicle, the trailer and the
permitted total weight of the trailer being
pulled. Above all, it must be securely and safely
attached to the vehicle trailer.
Never mount a trailer hitch on the bumper. The
trailer hitch must be mounted in a way that does
not impair the function of the bumper. Do not
make any changes to the exhaust system and the
brake system.
Check regularly if the trailer hitch is securely
mounted. Always follow the instructions given by
the trailer hitch manufacturer.
Trailer brakes
If the trailer has its own brake system, then fol-
low the manufacturer specifications. However,
the brake system on the trailer must never be
connected to the vehicle brake system.
Engine cooling system
Driving with a trailer means a higher load on the
engine and the cooling system. The cooling sys-
tem must be designed for additional load and
contain enough coolant > @®.
CG) Note
Longer inclines cannot be driven without a
suitable cooling system, especially if the out-
side temperatures are high. Otherwise, this
increases the risk of engine damage.
Operating instructions
Towing capacity
Your vehicle can only be operated with class 1 or
class 2 trailers.
Load distribution
Poor cargo load and distribution can negatively
impact vehicle handling. Load the trailer based
on the following criteria as much as possible:
— Store objects in the vehicle luggage compart-
ment, if possible. The vehicle should always
carry the heaviest possible load and the trailer
should have the lightest possible load.
— Distribute the load in the trailer so that the
heavy objects are as close to the axle as possi-
ble.
— Secure objects so that they do not slide.
— Utilize the maximum permitted tongue weight
if possible.
Tires
Set the tire pressure on your vehicle for a “full
load”; see the tire pressure sticker > page 245. If
necessary, also adjust the tire pressure on the
trailer according to the manufacturer's specifica-
tions.
The trailer and the vehicle should be equipped
with winter tires when driving in winter tempera-
tures.
Outside mirrors
If you cannot see the traffic behind the trailer
with the standard exterior mirrors, then you
must attach additional exterior mirrors. Adjust
them so you have a sufficient visibility behind
you.
Exterior lighting
Follow the legal regulations for lighting on your
trailer that are applicable in the country where
115
>

Trailer towing

you are operating the vehicle. Contact an author-
ized Audi dealer or authorized Audi Service Facili-
ty for more information.
Before you start driving, check all lighting equip-
ment on the trailer while it is hitched to the vehi-
cle.
The headlight range control automatically ad-
justs the light range of the headlights.
Safety chains
Make sure the safety chains are correctly applied
when pulling a trailer. The chains should hang
enough so that the trailer can drive around
curves. However, they must not touch the
ground.
@) Note
Attachments retrofitted on the vehicle may
cause damage, especially on the trailer hitch
ball head. In cases of damage, have the func-
tion checked by an authorized Audi dealer or
authorized Audi Service Facility.
@ Tips
— Block the wheels with chocks when parking
on inclines if the trailer is loaded.
— Audi recommends having the vehicle in-
spected between the inspection intervals if
you tow a trailer frequently.
— Avoid driving with a trailer during the vehi-
cle break-in period.
Driving with a trailer
Driving with a trailer requires extra caution.
Speed
Adhere to the legal speed limits. Follow the legal
regulations that are applicable in the country
where you are operating the vehicle.
As the speed increases, the driving stability of
the trailer decreases. Therefore you should not
exceed the maximum legal speed limit when
there are unfavorable road, weather, and/or wind
conditions. This especially applies when driving
downhill.
116
Hill
When you start driving uphill or downhill, trailers
may tilt or sway sooner than when driving ona
level surface. If small swaying movements have
already occurred, you can stabilize the trailer by
firmly braking immediately. Never attempt to
“straighten out” the trailer by accelerating.
Downshift before driving on hills to utilize the en-
gine braking effect > A\.
Brakes
When using a trailer with overrun brakes, first
brake gently then quickly. This reduces the risk of
jerking while braking if the trailer wheels lock up.
Engine coolant temperature
Pay attention specifically to the coolant tempera-
ture display when there are high outside temper-
atures, and when driving on long inclines
=> page 14. Shift to a higher gear in a timely man-
ner.

Z\ WARNING
Constant braking causes the brakes to over-
heat and can substantially reduce braking per-
formance, increase braking distance, or cause
complete failure of the brake system.