2018 MERCEDES-BENZ CLA COUPE check engine light

XTurn the fuel filler cap counterclockwise and
remove it.
XInsert the fuel filler cap into the holder on theinside of fuel filler flap =.
XCompletely insert the filler neck of the fuel
pump nozzle into the tank ,hook in place and
refuel.
XOnly fill the tank until the pump nozzle
switches off.
Do not add any more fuel after the pump stops
filling for the first time. Otherwise, fuel may leak
out.
Closing the fuel filler flap
XReplace the cap on the filler neck and turn
clockwise until it engages audibly.
XClose the fuel filler flap. Close the fuel filler flap before lockingt
he vehi-
cle.
If you are driving with the fuel filler cap open, the
8 reserve fuel warning lamp flashes. Ames-
sage appears in the multifunction display
(
Ypage 206).
In addition, the ;Check Engine warning
lamp may light up (
Ypage 224).
For further information on warning and indicator
lamps in the instrument cluster, see
(
Ypage 224).
Problems with fuel and the fuel tank
ProblemPossible causes/consequences and MSolutions
Fuel is leaking from the
vehicle.The fuel line or the fuel tank is faulty.
GWARNING
Risk of explosion or fire.
XApply the electric parking brake.
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
or, in vehicles with KEYLESS-GO start-function or KEYLESS ‑GO
XOpen the driver's door.
The vehicle electronics are now in positiong.This is the same as
the SmartKey being removed from the ignition.
XDo not restart the engine under any circumstances.
XConsult aqualified specialist workshop.
The fuel filler flap cannot
be opened.The fuel filler flap is not unlocked.
XUnlock the vehicle (Ypage 70).
The SmartKey battery is discharged or nearly discharged.
XUnlock the vehicle using the mechanical key (Ypage 77).
The fuel filler flap is unlocked, but the opening mechanism is jammed.
XConsult aqualified specialist workshop.
140Refueling
Driving and parking

Limited braking performance on salt-
treated roads
If you driveonsalted roads,alayer of salt resi-
due may for monthebraked iscsand brake
pads. This can result in asignificantly longer
braking distance.
RIn ordertop revent any salt build-up, apply the
brakes occasionally while paying attention to th et raffic conditions.
RCarefully depress th ebrakep edal and the
beginnin gand end of ajou rney.
RMaintain agreater distanc etothevehicle
ahead.
Servicing th ebrakes
!The brakef luid level may be to olow, if:
Rif th ered brakew arning lamp lightsupi n
th ei nstrumentc luster and
Ryou hearawarning tone while th eengine is
running
Observe additional warning messages in the
multifunction display.
The brakef luid level may be to olow due to
brak epad wear or leaking brak elines.
Hav ethe brakes ystem checked immediately.
Consult aqualifie dspecialist workshop to
arrange this.
!Af unction or performanc etests hould only
be carried out on a2-axle dynamometer. If
you wish to operate th evehicle on such a
dynamometer, please consult aqualifie dspe-
cialis tworkshop in advance. You could oth-
erwis edamage th edrivet rain or th ebrake
system.
!As th eESP®system operates automatically,
th ee ngine and th eignitio nmust be switched
off (th eSmartKey must be in position uor
1 in th eignitio nlock), if th eelectric parking
brakeist ested onabraking dynamometer
(maximum 10 seconds).
Brakin gtriggered automatically by ESP
®may
cause severe damage to th ebrakes ystem.
All check sand maintenanc ework on th ebrake
system must be carried out at aqualifie dspe-
cialis tworkshop.
Hav ebrakep ads installe dand brakef luid
replaced at aqualifie dspecialist workshop. If th
ebrakes ystem has onl ybeen subject to
moderatel oads, you should tes tthe functional-
ity of your brakes at regular intervals.
You can fin dadescription of Brake Assist (BAS
)
on (Ypage 61).
Mercedes-Ben zrecommend stha tyou onl yhave
brak epads/linings installe donyour vehicle
whichh ave been approved for Mercedes-Benz
vehicle sorwhichcorrespondtoane quivalent
qualitys tandard. Brake pads/linings whichh ave
not been approved for Mercedes-Ben zvehicles
or whicha re not of an equivalent qualityc ould
affect your vehicle's operatin gsafety.
Mercedes-Ben zrecommend sthaty ou onl yuse
brakef luid that has been specially approved for
your vehicle by Mercedes-Benz, or whichc orre-
sponds to an equivalent qualitys tandard. Brake
fluid whichh as not been approved for
Mercedes-Ben zvehicle sorw hichisn ot of an
equivalent qualityc ould affect your vehicle's
operatin gsafety.
Checkingb rake lining thickness
You can measure th ebreak pad/linin gthick-
nes susingat estg age. Color-coding( green or
red) on th etestg age allows you to determine
whether th ebrakep ad/linin gthicknes sisstill
sufficient .The tes tgage is in th evehicle docu-
mentw allet in th egloveb ox.
Front wheel
Driving tips147
Driving and parking
Z

Important safety notes
GWARNING
If you operate information systems and com-
munication equipmen tintegrate dinthevehi-
cle when driving ,you may be distracte dfrom
th et raffic situation .You could also lose con-
trol of th evehicle. Ther eisariskofana cci-
dent.
Only operate this equipmen twhen th etraffic
situation permits. If you are no tsuret hatthis
is possible ,park th evehicl epayin gattention
to traffic condition sand operate th eequip-
men twhen th evehicl eiss tationary.
You must observ ethe legal requirements for th e
country in whic hyou are currentl ydriving when
operating th eon-bo ard computer.
GWARNIN G
If th einstrumen tcluste rhas faile dormal-
functioned, you may no trecognize function
restriction sinsystems relevan ttosafety. The
operating safet yofyour vehicl emay be
impaired .Ther eisar iskofana ccident.
Drive on carefully. Hav ethe vehicl echecked
at aq ualified specialist workshop immedi-
ately.
The on-board computer only shows message sor
warning sfromc ertai nsystems in th emultifunc-
tion display. You should therefor emakes ure
your vehicl eisoperating safely at all times .
If th eoperating safet yofyour vehicl eis
impaired ,pull ove rassoonasitiss afetodos o.
Contac taqualified specialist workshop.
Fo rano verview, see th einstrumen tpanel illus-
tration (
Ypage 33).
Display sand operation
Instrumen tcluster lighting
The ligh tsensor in th einstrumen tcluste rauto -
matically control sthe brightness of th emulti-
function display. In daylight, th edisplays in th e
instrumen tcluste rare no tilluminated. The lighting in th
einstrumen tcluster, in th edis-
plays and th econtrols in thevehicl einterior can
be adjusted usin gthe brightness control knob.
The brightness control knob is locate donthe
botto mleftoft heinstrumen tcluste r
(
Ypage 33).
XTurn th ebrightness control knob clockwise or
counter-clockwise.
If th eligh tswitch is set to th eÃ, Tor
L position ,the brightness is dependen t
upon th ebrightness of th eambien tlight.
Speedometer with segments
The speedometer is divided int osegments on
vehicles wit hDistance Pilot DISTRONIC.
The segments in th espeedometer indicat e
whic hspee drange is available.
RDistanc ePilot DISTRONI Cisactivated
(Ypage 151):
On eort wo segments in th eset spee drange
ligh tup.
RDistanc ePilot DISTRONI Cdetects avehicl ein
fron tmoving mor eslowly than th estored
speed:
The segments between th espee doft hevehi-
cle in fron tand th estoreds pee dligh tup.
Tachometer
!
Do no tdriveint heoverrevving range, as this
could damag ethe engine.
The red ban dinthetachometer indicates th e
engine's overrevving range.
The engin eislimite dwithin arange to protect
th ee nginew hen th ered ban disreached.
Outsidet emperatur edisplay
You should pay special attention to road condi-
tion swhen temperatures are aroun dfreezing
point.
Bea rinm indt hatthe outside temperature dis-
play indicates th etem perature measured and
does no trecord th eroad temperature.
The outside temperature display is in th emulti-
function display (
Ypage 179).
176Displaysand operation
On-boardc omputer and displays

Display messagesPossible causes/consequences andMSolutions
The yellow!warning lamp lights up and th ered F (USAonly)
or ! (Canada only) indicator lamp flashes .
It is no tpossibl etoapply th eelectric parking brak emanually.
XShift th etransmission to position B.
XVisitaqualified specialist workshop .
$(USAonly)
J(Canada only)
Check Brake Fluid
Level
There is no tenough brak efluidint hebrak efluid reservoir .
Aw arning tone sounds. The $(USAonly) or J (Canada only)
warning lamp sintheinstrumen tcluste rmay also ligh tup.
GWARNIN G
The braking effec tmay be impaired.
There is ariskofana ccident.
XPull overand stop th evehicl esafely as soo naspossible, payin g
attention to roa dand traffic conditions. Do no tcontinue driving
under any circumstances.
XSecur ethe vehicl eagainst rollin gaway (Ypage 141).
XConsult aqualified specialist workshop .
XDo notadd brak efluid .This does no tcorrect them alfunction .
#
CheckBrakePadWear
The brak epads/linings hav ereached their wear limit.
XVisit aqualified specialist workshop .
G
Inoperative
Oneorm orem ain features of th embrace system are malfunctioning .
XVisitaqualified specialist workshop .
ActiveBrakeAssistFunctionsCurrentlyLimitedSee Opera‐tor's Manual
Active Brake Assis tistemporarily inoperative.
Possibl ecauses are:
RThe radar sensor system is temporarily inoperative, e.g. due to
electromagneti cradiation emitted by nearby TV or radi ostation sor
other source sofelectromagneti cradiation .
RThe system is outside th eoperating temperature range.
RThe on-boar dvoltag eistoolow.
Whe nthe causes state dabov enol onger apply, th edisplay message
disappears.
Active Brake Assis tisoperational again .
If th edisplay message does no tdisappear :
XPull overand stop th evehicl esafely as soo naspossible, payin g
attention to roa dand traffic conditions.
XSecur ethe vehicl eagainst rollin gaway (Ypage 141).
XRestart th eengine.
Active BrakeAssist :SystemInop‐erative
Active Brake Assis tisunavailable due to amalfunction .Situation -
dependen tbraking assistanc emay also hav efailed.
XVisit aqualified specialist workshop immediately.
Display messages197
On-boardc omputer andd isplays
Z

Warning/
indicator
lampNSignal type
Possiblec auses/consequences and M
Solutions
!FNF (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.
XObserve the additiona ldisplay messages in the multifunction display.
6N The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
GWARNING
The air bagsorE mergency Tensioning Devices may either be triggeredu ninten-
tionally or, in the event of an accident, may not be triggered.
There is an increased risk of injury.
XObserve the additionald isplay messages in the multifunction display.
XDrive on carefully.
XContactaqualified specialist workshopa nd have the restraint system checked.
For further information about the restraint system, see (
Ypage4 0).
Engine
Warning/
indicator
lampNSignal type
Possiblec auses/consequences and M
Solutions
;NThe yellow Check Engine warning lamp lights up while the engine is running.
There may be amalfunction, for example:
Rin the engine management
Rin the fuel injection system
Rin the exhaust system
Rin the ignitio nsystem
Rin the fuel system
The emission limitv alues may be exceededa nd the engine may be in emergency
mode.
XVisitaq ualified specialist workshopi mmediately.
iIn some states, you must immediatel yvisit aqualified specialist workshopa s
soon as the yellow Check Engine warning lamp lights up. This is due to the legal
requirements in effect in these states. If in doubt, check whethers uch legal
regulations apply in the state in which you are currently driving.
æN The yellow reserve fuel warning lamp lights up while the engine is running.
The fuel levelh as dropped into the reserve range.
XRefuel at the neares tgas station.
224Warning and indicator lamps in the instrument cluster
On-board computer and displays

Warning/
indicator
lampNSignal type
Possiblec auses/consequences and M
Solutions
æNThe yellow reserve fuel warning lamp flashes while the vehicleisinm otion.
In addition, the ;Check Engine warning lamp may light up.
The fuel filler cap is not closed correctly or the fuel system is leaking.
XCheck that the fuel filler cap is correctly closed.
XIf the fuel filler cap is not correctly closed: close the fuel filler cap.
XIf the fuel filler cap is closed:visitaqualified specialist workshop.
?NThe red coolant warning lamp lights up while the engine is running and the
coolant temperature gage is at the start of the scale.
The temperature sensor for the coolant temperature gauge is malfunctioning.
The coolant temperature is no longer being monitored.T here isarisk of engine
damage if the coolant temperature is too high.
XPul lover and stop the vehicles afelyand switch off the engine, paying attention
to road and traffic conditions. Do not continue driving under any circumstances.
XSecure the vehiclea gainst rolling away(Ypage141).
XConsult aqualified specialist workshop.
Warning and indicator lamps in the instrument cluster225
On-board computer and displays
Z

XMake sure that the windshield wipers are
switched off.
XPull release lever:on the hood.
The hood is released.
XReach into the gap between the hood and the radiator trim and press hood catch lever ;to
the left.
XRaise the hood.
XPull support strut ?out of bracket A.
XLift up support strut ?and insert it into yel-
low retaining clip =.
Closing the hood
XRaise the hood slightly and, at the same time,
remove support strut ?from yellow retaining
clip =.
XSwing support strut ?down and press it into
bracket Auntil it engages.
XLower the hood and let it fall from aheight of
approximately 8in(20 cm).
XCheck that the hood has engaged properly.
If the hood can be raised slightly, it is not
properly engaged. Do not press the hood
closed. Open the hood again and close it with
alittle more force.
Engine oil
General notes
Depending on your driving style, the vehicle
consumes up to 0.9 US qt (0.8 liters) of oil per
600 miles (1,000 km). The oil consumption may
be higher than this when the vehicle is new or if
you frequently drive at high engine speeds.
Depending on the engine, the oil dipstick may be
in ad ifferent location.
When checking the oil level:
Rpark the vehicle on alevel surface
Rthe engine should be switched off for approx-
imately five minutes if the engine is at normal
operating temperature
Rif the engine is not at normal operating tem-
perature, e.g. if the engine was only started
briefly, wait about 30 minutes before carrying
out the measurement
Checking the oil level using the oil dip-
stick
GWARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very hot.
Working in the engine compartmentp oses a
risk of injury.
Where possible, let the engine cool down and touch only the components described in the
following.
258Engine compartment
Maintenance and care

GWARNING
During charging and jump-starting, explosive gasesc an escapefrom the battery .There is arisk
of an explosion.
Particularl yavoi dfire, open flames, creating sparks and smoking. Ensure there is sufficient ven-
tilation while charging and jump-starting. Do not leano verabattery.
GWARNING
During the charging process,ab attery produces hydrogen gas. If ashort circui toccurs or sparks
are created ,the hydrogen gas can ignite. There is arisk of an explosion.
RMake sure that the positive terminal of aconnected battery does not come into contact with
vehiclep arts.
RNever place metal objects or tools on abattery.
RIt is important that you observe the described order of the battery terminal swhen connecting
and disconnecting abattery.
RWhen jump-starting, make sure that the battery polesw ith identical polarity are connected.
RIt is particularlyimportant to observe the described order when connecting and disconnecting
the jumper cables.
RNever connect or disconnect the battery terminal swhile the engine is running.
GWARNING
Ad ischarged battery can freeze at temperatures below freezing point. When jump-starting the
vehicleorc harging the battery,g asescan escapef rom the battery.T here isarisk 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 coul dbe
damaged by the non-combusted fuel.
If the indicator/warning lamp sdonot light up in the instrument cluster at low temperatures, it is very
likelyt hat the discharged battery has frozen. In this case you may neither jump-start the vehiclen or
charge the battery.L et the battery thaw first. The service life of athawed-out battery may be shorter.
The starting characteristics can be impaired,p articularlyatlow temperatures. Have the thawed-out
battery checked at aqualified specialist workshop.
Do not start the vehicleu singarapi dc harging device. If you rvehicle's battery is discharged, the
engine can be jump-started from another vehicleorf romasecond battery using jumper cables.
Observe the following points:
RThe battery is not accessible in all vehicles. If the other vehicle's battery is not accessible,j ump-
start the vehicleu singasecond battery or ajump-starting device.
RYou may only jump-start the vehiclew hen the engine and exhaust system are cold.
RDo not start the engine if the battery is frozen. Let the battery thaw first.
ROnly jump-start from batterieswitha12Vv oltagerating.
ROnly use jumper cables that are not damaged and have asufficient cross-section and insulated
terminal clamps.
RMake sure that the two vehicles do not touch.
Jump-starting279
Breakdown assistance
Z