2017 MERCEDES-BENZ CLA check engine light

Limited braking performance on salt-
treated roads If you drive on salted roads, a layer of salt resi-
due may form on the brake discs and brake
pads. This can result in a significantly longer
braking distance. R
In order to prevent any salt build-up, apply the
brakes occasionally while paying attention to
the traffic conditions. R
Carefully depress the brake pedal and the
beginning and end of a journey. R
Maintain a greater distance to the vehicle
ahead.
Servicing the brakes
! The brake fluid level may be too low, if: R
if the red brake warning lamp lights up in
the instrument cluster and R
you hear a warning tone while the engine is
running
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately.
Consult a qualified specialist workshop to
arrange this.
! A function or performance test should only
be carried out on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult a qualified spe-
cialist workshop in advance. You could oth-
erwise damage the drive train or the brake
system.
! As the ESP ®
system operates automatically,
the engine and the ignition must be switched
off (the SmartKey must be in position 0 or 1 in
the ignition lock) if: R
the electric parking brake is tested on a
brake dynamometer (for a maximum of
ten seconds) R
the vehicle is towed with the front axle
raised.
Braking triggered automatically by ESP ®
may
seriously damage the brake system.
All checks and maintenance work on the brake
system must be carried out at a qualified spe-
cialist workshop. Have brake pads installed and brake fluid
replaced at a qualified specialist workshop.
If the brake system has only been subject to
moderate loads, you should test the functional-
ity of your brakes at regular in t ervals.
You can find a description of Brake Assist (BAS)
on ( Y
page 60).
Mercedes-Benz recommends that you only have
brake pads/linings installed on your vehicle
which have been approved for Mercedes-Benz
vehicles or which correspond to an equivalent
quality standard. Brake pads/linings which have
not been approved for Mercedes-Benz vehicles
or which are not of an equivalent quality could
affect your vehicle's operating safety.
Mercedes-Benz recommends that you only use
brake fluid that has been specially approved for
your vehicle by Mercedes-Benz, or which corre-
sponds to an equivalent quality standard. Brake
fluid which has not been approved for
Mercedes-Benz vehicles or which is not of an
equivalent quality could affect your vehicle's
operating safety.
Checking brake lining thickness You can measure the break pad/lining thick-
ness using a test gage. Color-coding (green or
red) on the test gage allows you to determine
whether the brake pad/lining thickness is still
sufficient. The test gage is in the vehicle docu-
ment wallet in the glove box.
Front wheel146
Driving tips
Driving and parking

Important safety notes
G WARNIN G
If you operate information systems and com-
munication equipmen t integrate d in th e vehi-
cle while driving , you will be distracte d from
traffic conditions. You could also lose control
of th e vehicle. Ther e is a ris k of an accident.
Only operate th e equipmen t when th e traffic
situation permits. If you are no t sur e that this
is possible , park th e vehicl e payin g attention
to traffic condition s and operate th e equip-
men t when th e vehicl e is stationary.
You must observ e th e legal requirements for th e
country in whic h you are currentl y driving when
operating th e on-board computer.
G WARNIN G
If th e instrumen t cluste r has faile d or mal-
functioned, you may no t recognize function
restriction s in systems relevan t to safety. The
operating safet y of your vehicl e may be
impaired . Ther e is a ris k of an accident.
Drive on carefully. Hav e th e vehicl e checke d
at a qualified specialist workshop immedi-
ately.
The on-board computer only shows message s or
warning s from certain systems in th e multifunc-
tion display. You should therefor e mak e sur e
your vehicl e is operating safely at all times .
If th e operating safet y of your vehicl e is
impaired , pull ove r as soo n as it is saf e to do so.
Contac t a qualified specialist workshop.
Fo r an overview, see th e instrumen t panel illus-
tration ( Y
page 32).
Displays and operation
Instrument cluster lighting
The ligh t sensor in th e instrumen t cluste r auto -
matically control s th e brightness of th e multi-
function display. In daylight, th e displays in th e
instrumen t cluste r are no t illuminated.
The lighting in th e instrumen t cluster, in th e dis-
plays and th e control s in th e vehicl e interior can
be adjusted usin g th e brightness control knob. The brightness control knob is locate d on th e
botto m lef t of th e instrumen t cluste r
( Y
page 32). X
Turn th e brightness control knob clockwise or
counter-clockwise.
If th e ligh t switch is set to th e X , ` or
X position , th e brightness is dependen t
upon th e brightness of th e ambien t light.
Speedometer with segments The speedometer is divided int o segments on
vehicles wit h Distanc e Pilot DISTRONIC.
The segments in th e speedometer indicat e
whic h spee d range is available. R
Distanc e Pilot DISTRONI C is activated
( Y
page 150):
On e or two segments in th e set spee d range
ligh t up. R
Distanc e Pilot DISTRONI C detects a vehicl e in
fron t moving mor e slowly than th e store d
speed:
The segments between th e spee d of th e vehi-
cle in fron t and th e store d spee d ligh t up.
Tachometer
! Do no t driv e in th e overrevving range, as this
could damag e th e engine.
The red ban d in th e tachometer indicates th e
engine's overrevving range.
The engin e is limite d within a range to protect
th e engin e when th e red ban d is reached.
Outside temperature display You should pay special attention to road condi-
tion s when temperatures are aroun d freezing
point.
Bea r in min d that th e outside temperature dis-
play indicates th e temperature measured and
does no t record th e road temperature.
The outside temperature display is in th e multi-
function display ( Y
page 176).
Ther e is a short delay before a chang e in outside
temperature appear s in th e multifunction dis-
play.174
Displays and operation
On-board computer and displays

Display messages
Possible causes/consequences and P Solutions
The yellow $ warning lamp lights up and th e red I (US A only)
or $ (Canada only) indicator lamp flashes .
It is no t possibl e to apply th e electric parking brak e manually.X
Shift th e transmission to position P .X
Visit a qualified specialist workshop .
' (USA
only)
M ( Canada
only)
Check Brake Fluid
Level There is no t enough brak e fluid in th e brak e fluid reservoir .
A warning tone sounds. The ' (US A only) or M (Canada only)
warning lamp s in th e instrumen t cluste r may also ligh t up.
G WARNIN G
The braking effec t may be impaired.
There is a ris k of an accident.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions. Do no t continu e drivin g
under any circumstances. X
Secur e th e vehicl e against rollin g away ( Y
page 140).X
Consult a qualified specialist workshop .X
Do no t add brak e fluid . This does no t correc t th e malfunction .
& Check Brake Pad Wea r The brak e pads/linings hav e reached their wear limit.X
Visit a qualified specialist workshop .
S Inoperative On e or mor e main features of th e mbrace system are malfunctioning .X
Visit a qualified specialist workshop .
Active Brake Assist
Functions Currently
Limite d See Opera‐
tor's Manual Active Brake Assis t is temporarily inoperative.
Possibl e causes are: R
th e radar sensor system is temporarily inoperative, e.g. due to elec -
tromagneti c radiation emitted by nearby TV or radi o station s or
other source s of electromagneti c radiationR
th e system is outside th e operating temperature rangeR
th e on-boar d voltag e is to o low
Whe n th e causes state d abov e no longer apply, th e display message
disappears.
Active Brake Assis t is operational again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 140).X
Restart th e engine.
Active Brake
Assist : System Inop‐
erativ e Active Brake Assis t is unavailable due to a malfunction . Situation -
dependen t parking assistanc e may also hav e failed.X
Visit a qualified specialist workshop immediately.194
Display messages
On-board computer and displays

Warning/
indicator
lamp Q Signal type
Possible causes/consequences and P Solutions
$I
Q I (USA only), $ (Canada only): the red indicator lamp for the electric
parking brake flashes or lights up and/or the yellow warning lamp for the electric
parking brake lights up. X
Observe the additional display messages in the multifunction display.
u
Q The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
G WARNING
The air bags or Emergency Tensioning Devices may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
There is an increased risk of injury. X
Observe the additional display messages in the multifunction display. X
Drive on carefully. X
Contact a qualified specialist workshop and have the restraint system checked.
For further information about the restraint system, see ( Y
page 39).
Engine Warning/
indicator
lamp Q Signal type
Possible causes/consequences and P Solutions

G WARNING
During charging and jump-starting, explosive gases can escape from the battery. There is a risk
of an explosion.
Particularly avoid fire, open flames, creating sparks and smoking. Ensure there is sufficient ven-
tilation while charging and jump-starting. Do not lean over a battery.
G WARNING
During the charging process, a battery produces hydrogen gas. If a short circuit occurs or sparks
are created, the hydrogen gas can ignite. There is a risk of an explosion. R
Make sure that the positive terminal of a connected battery does not come into contact with
vehicle parts. R
Never place metal objects or tools on a battery. R
It is important that you observe the described order of the battery terminals when connecting
and disconnecting a battery. R
When jump-starting, make sure that the battery poles with identical polarity are connected. R
It is particularly important to observe the described order when connecting and disconnecting
the jumper cables. R
Never connect or disconnect the battery terminals while the engine is running.
G WARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle or charging the battery, gases can escape from the battery. There is a risk of an explosion.
Allow the frozen battery to thaw out before charging it or jump-starting.
! Avoid repeated and lengthy starting attempts. Otherwise, the catalytic converter could be
damaged by the non-combusted fuel.
If the indicator/warning lamps do not light up in the instrument cluster at low temperatures, it is very
likely that the discharged battery has frozen. In this case you may neither jump-start the vehicle nor
charge the battery. Let the battery thaw first. The service life of a thawed-out battery may be shorter.
The starting characteristics can be impaired, particularly at low temperatures. Have the thawed-out
battery checked at a qualified specialist workshop.
Do not start the vehicle using a rapid charging device. If your vehicle's battery is discharged, the
engine can be jump-started from another vehicle or from a second battery using jumper cables.
Observe the following points: R
The battery is not accessible in all vehicles. If the other vehicle's battery is not accessible, jump-
start the vehicle using a second battery or a jump-starting device. R
You may only jump-start the vehicle when the engine and exhaust system are cold. R
Do not start the engine if the battery is frozen. Let the battery thaw first. R
Only jump-start from batteries with a 12 V voltage rating. R
Only use jumper cables that are not damaged and have a sufficient cross-section and insulated
terminal clamps. R
Make sure that the two vehicles do not touch.274
Jump-starting
Breakdown assistance