MERCEDES-BENZ M-Class 2012 W166 Owner's Manual

Warning
andindic atorlamps inthe instrument cluster Seat
belt Probl
em Pos
siblecause s/cons equen cesand M Sol
utions 7
After
starting the
engine, thered seat
bel twarn ing lamp lights
up for sixsec onds. The
seat beltwarn inglamp remindsth edriv erand fron tpasse nger
to fast entheir seat belts.
X Fas teny our seat belt(Ypage 49). 7
Aft
erstart ingthe
engine, thered seat
belt warning lamplights
up. Inaddition, a
warning tonesounds
for uptosix seconds. G
Risk
ofinjur y The
driver's seatbeltisnot fastened.
X Fasten yourseatbelt(Ypage 49).
The warning toneceases. 7
The
redseat belt
warning lamplights up
after theengine starts,
as soon asthe driver's
or the front -passenger
door isclosed. G
Risk
ofinjur y The
driver orfront passenger hasnotfastened theirseatbelt.
X Fasten yourseatbelt(Ypage 49).
The warning lampgoesout. G
Risk
ofinjur y There
areobject son the front -passenger seat.
X Remove theobject sfrom thefront -passenger seatandstow
them inasecure place.
The warning lampgoesout. War
ning andindicator lampsin the instru mentcluster
269On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
7
The
redseat belt
warning lampflashes
and aninterm ittent
audi blewarning
sounds. G
Risk
ofinjury The
driver orfront passenger hasnotfastened theirseatbelt. In
addition, youaredriving fasterthan15mph (25km/ h)or you have
briefly drivenfasterthan15mph (25km/ h).
X Fasten yourseatbelt(Ypage 49).
The warning lampgoesoutand theinter mittentwarning tone
ceases. G
Risk
ofinjur y There
areobject son the front -passenger seat.Inaddition, youare
driving fasterthan15mph (25km/ h)or you have briefly driven
faster than15mph (25km/ h).
X Remove theobject sfrom thefront -passenger seatandstow
them inasecure place.
The warning lampgoesoutand theinter mittentwarning tone
ceases. 270
War
ning andindicator lampsin the instru mentclusterOn-board computer and displays

Safety
systems Problem Possible
causes/co nsequences andM Solutions
$
(USAonly)
J (Canada only)
The redbrake system
warning lampcomes on
while theengine is
running. Awarning tone
also sounds. G
Risk
ofaccident The
brake boosting effectismalfunction ingand thebraking
characterist icsmay beaffected.
X Pull over andstop thevehicle safelyassoon aspossible, paying
atten tiontoroad andtraffic condition s.Do not cont inue driving
under anycircumst ances.
X Engage theelectric parking brake.
X Consult aqual ified specialist workshop.
X Observe theadditional displaymessages inthe multifunct ion
display . $
(USAonly)
J (Canada only)
The redbrake system
warning lampcomes on
while theengine is
running. Awarning tone
also sounds. G
Risk
ofaccident There
isnot enough brakefluidinthe brake fluidreservoir.
X Pull over andstop thevehicle safelyassoon aspossible, paying
atten tiontoroad andtraffic condition s.Do not cont inue driving
under anycircumst ances.
X Engage theelectric parking brake.
X Consult aqual ified specialist workshop immediately.
X Observe theadditional displaymessages inthe multifunct ion
display .
Do not add brake fluid.Thiswillnotrectify themalfunction . G
WARNING Driving
withthebrake warning lampilluminated canresult inan accident. Haveyourbrake system
check edimmediately ifthe brake warning lampstays on.Donot add brake fluidbefore checking
the brake system.
Overfilling thebrake fluidreservoir canresult inspilling brakefluidonhot engine partsandthe
brake fluidcatchin gfire. Youcanbeseriously burned. War
ning andindicator lampsin the instrum entcluster
271On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
!
The
yello wABS warning
lamp islit while the
engine isrunning. G
Risk
ofaccident ABS
(Anti-lock Brake System) isdeactivated duetoamalfunction .
BAS (Brake Assist), BASPLUS, ESP®
(Electr onicStability
Program), PRE-SAFE®
,PRE-SA FE®
Brake, theHOLD function,hill
start assist andESP®
trailer stabilization aretherefore also
deactivated, forexample.
The brake system continues tofunct ionnormally, butwithout the
funct ionslisted above. Thewheels couldtherefore lockifyou
brake hard,forexample.
ATTENTI ONASS ISTisdeactivated.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Drive oncarefully.
X Visit aqual ified specialist workshop.
If the ABS controlunit isfaulty, thereisalso apossibili tythat other
systems, suchasthe navigation systemorthe automatic
transm ission,willnotbeavaila ble. !
The
yello wABS warning
lamp islit while the
engine isrunning. G
Risk
ofaccident ABS
istemporarily unavailable.BAS,BAS PLUS, ESP®
,EBD
(electronic brakeforcedistribution), PRE-SAFE®
,
PRE-SA FE®
Brake, theHOLD function,hillstart assist and
ESP ®
trailer stabilization aretherefore alsodeactivated, for
example.
Self diagnosis isnot yetcomplete orthe on-board voltagemaybe
insufficient ,for example.
The brake system continues tofunct ionnormally, butwithout the
funct ionslisted above. Thewheels couldtherefore lockifyou
brake hard,forexample.
ATTENTI ONASS ISTisdeactivated.
X Carefull ydrive asuitable distance makingslightsteering
movement sat aspeed above12mph (20km/ h).
The funct ionsment ioned above areavaila bleagain whenthe
warning lampgoesout.
If the warning lampisstill on:
X Observe theadditional displaymessages inthe multifunct ion
display .
X Drive oncarefully.
X Visit aqual ified specialist workshop. 272
War
ning andindicator lampsin the instrum entclusterOn-board computer and displays

Problem Possible
causes/co nsequences andM Solutions
!
The
yello wABS warning
lamp islit while the
engine isrunning. A
warning tonealso
sounds. G
Risk
ofaccident EBD
isfaulty. Therefore, BAS,BAS PLU S,ESP ®
,PR E-SAFE ®
,PR E-
SAFE ®
Bra ke, the HOLD functio n,hillsta rtas sist and ESP®
tra iler
sta bilizati onarealso una vailab le,for exa mpl e.
The brakesystem continuestofunct ionnormally, butwithout the
funct ionslisted above. Thewheels couldtherefor elock ifyou
brake hard,forexample.
ATTE NTION ASSISTisdeactivated.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Drive oncarefully.
X Visit aquali fiedspecialist workshop. $
(USAonly)
J (Canada only)
֌!
The redbrake warning
lamp, theyellow ESP®
and ESP®
OFF warning
lamps andtheyellow
ABS warning lampare
lit while theengine is
runnin g. G
Risk
ofaccident ABS
andESP®
are faulty. Therefore, BAS,BAS PLUS, EBD,PRE-
SAF E®
,PRE-S AFE®
Brake, theHOLD function,hillstart assist and
ESP ®
trailer stabilization arealso unavailab ledue toa
malfunct ion,forexample.
The brake system continues tofunct ionnormally, butwithout the
funct ionslisted above. Thewheels couldtherefor elock ifyou
brake hard,forexample.
ATTE NTION ASSISTisdeactivated.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Drive oncarefully.
X Visit aquali fiedspecialist workshop. ÷
The
yellow ESP®
warning lampflashes
while thevehicle isin
motion . G
Risk
ofaccident ESP
®
or tract ioncont rolhas interv enedbecause thereisarisk of
skidding oratleast onewheel hasstart edtospin.
Cruise controlorDIS TRONIC PLUSisdeactivated.
X Only depress theaccelerator pedalasfar asnecessary when
pulling away.
X Ease offthe accelerator pedalwhilethevehicle isin motion .
X Adapt yourdriving styletosuit theroad andweather conditions.
X Do not deactivate ESP®
.
Ex ception s:(Y page 63). War
ning andindicator lampsin the instru mentcluster
273On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
å
The
yello wESP ®
OFF
warning lampislit while
the engine isrunning. G
Risk
ofaccident ESP
®
and ESP®
trailer stabilization aredeactivated. ESP®
will not
stabilize thevehicle ifit starts toskid orifawheel startstospin.
X Reactivate ESP®
.
Exc eptions: (Ypage 63).
X Adapt yourdriving styletosuit theroad andweather condition s.
If ESP ®
cannot beactivated:
X Have ESP®
check edataqual ified specialist workshop. ֌
The
yello wESP ®
and
ESP ®
OFF warning
lamps arelitwhile the
engine isrunning. G
Risk
ofaccident ESP
®
,BAS ,BAS PLUS, PRE-SA FE®
,PRE-SA FE®
Brake, theHOLD
funct ion,hillstart assist andESP®
trailer stabilization are
unavaila bledue toamalfunction .ESP ®
wi llnot stab ilize the vehicle
if it star tsto skid orifawh eel star tsto spi n.
The brakesystem continu estofuncti onnorma lly, bu tw itho utthe
func tionslist ed above.
ATT ENTION ASSIS Tis deact ivated.
X Obser vethe additio naldisplay messages inthe mult ifunc tion
display.
X Dr ive oncare fully.
X Visit aqualified specialist workshop. 274
Wa
rnin gand indica torlam psintheinstr ument clust erOn-board computer and displays

Problem Possible
causes/co nsequences andM Solutions
֌
The
yello wESP ®
and
ESP ®
OFF warning
lamps arelitwhile the
engine isrunning. G
Risk
ofaccident ESP
®
,BAS ,PRE-SA FE®
,the HOLD function,hillstart assist and
ESP ®
trailer stabilization aretemporarily unavailable.
BAS PLUS andPRE-SA FE®
Brake mayalsohave failed.
ESP ®
will notstabilize thevehicle ifit starts toskid orifawheel
starts tospin.
Self diagnosis isnot yetcomplete.
The brake system continues tofunct ionnormally, butwithout the
funct ionslisted above. Thewheels couldtherefore lockifyou
brake hard,forexample.
ATTENTI ONASS ISTisdeactivated.
X Carefull ydrive asuitable distance makingslightsteering
movement sat aspeed above12mph (20km/ h).
The funct ionsment ioned above areavaila bleagain whenthe
warning lampgoesout.
If the warning lampisstill on:
X Observe theadditional displaymessages inthe multifunct ion
display .
X Drive oncarefully.
X Visit aqual ified specialist workshop. $
(USAonly)
! (Canada only)
The redindicator lamp
for the electric parking
brake flashes and/or
the yello w
!
warning lampforthe
electric parking brake
lights up. The
electric parking brakeistemporarily malfunctioningor
defective.
X Observe theadditional displaymessages inthe multifunct ion
display . 6
The
redSRS warning
lamp islit while the
engine isrunning. G
Risk
ofinjury The
restraint systemsaremalfunction ing.Theairbags orETDs
may either betriggered unintentionally or,inthe event ofan
accident, notbetriggered atall.
X Drive oncarefully.
X Visit aqual ified specialist workshop immediately. War
ning andindicator lampsin the instrum entcluster
275On-board computer and displays Z

G
WARNING In
the event amalfu nction ofthe SRS isindica tedasoutli nedabove,the SRS may notbe
opera tional.
For yoursafet y,we stron gly recomm endthat you contactana uth oriz edMer cedes-Ben zCent er
immediately tohave thesystem checked.Other wisetheSRS may notbeactivat edwhen needed
in an acciden t,which couldresult inserious orfatal injury, oritmight deploy unexpec tedlyand
unnec essarily whichcouldalsoresult ininjury. Engine
Problem Possible
causes/consequences andM Solutions
;
The
yellow Check
En gine warning lamp
lights upwhile the
engine isrunn ing. There
maybeamalfunct ion,forexample:
R in the engine managemen t
R in the fuel injec tionsystem
R in the exhaust system
R in the ignition system(forvehicles withagasoline engine)
R in the fuel system
The emission limitvalues maybeexceeded andtheengine may
be runn inginemergen cymode.
X Have thevehicle checkedassoon aspossible ataqualified
specialist workshop. i
In
some states,you arerequired bylaw toimmediately visita
qualified specialist workshop assoon asthe yellow Check
En gine warning lamplights up.Ifin doubt, checkwhether such
legal regulations applyinthe state/prov inceinwhich youare
current lydriving. Vehicles
withadiesel engine: thefuel tank hasbeen rundry
(Y page 152).
X Start theengine threetofour times afterrefueling.
If the yellow Check Enginewarning lampgoesout,emergency
running modeiscanceled. Thevehicle neednotbecheck ed. 8
The
yellow reserve fuel
warning lampflashes
while thevehicle isin
motion. Inaddition, the
yell ow Check Engine
warning lamp;
may light up. The
fuel system pressure istoo low. Thefuel filler capisnot closed
correct lyor the fuel system isleaking.
X Observe theadditional displaymessages inthe multifunction
displa y.
X Check thatthefuel filler capiscorrect lyclosed.
X Ifthe fuel filler capisnot correctly closed:close thefuel filler
cap.
X Ifthe fuel filler capisclose d:visit aqual ified specialist
workshop. 276
War
ning andindicator lampsin the instrum entclusterOn-board computer and displays

Problem Possible
causes/co nsequences andM Solutions
8
The
yello wreserve fuel
warning lamplights up
while theengine is
running. The
fuel level hasdropped intothereserve range.
X Refuel atthe nearest gasstation. ?
The
redcoolant
warning lamplights up
while theengine is
running andthecoolant
temperature gaugeis
at the start ofthe scale. The
temperature sensorforthe coolant temperature gaugeis
defective.
The coolant temperature isno longer beingmonitor ed.There isa
risk ofengine damage ifthe coolant temperature istoo high.
X Pull over andstop thevehicle safelyandswitch offthe engine,
payi ngatten tiontoroad andtraffic condition s.Do not cont inue
driving underanycircumst ances.
X Apply theelectric parking brake.
X Consult aqual ified specialist workshop. War
ning andindicator lampsin the instrum entcluster
277On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
?
The
redcoolant
warning lampcomes on
while theengine is
running. The
coolant levelistoo low.
If the coolant leveliscorrec t,the airflow tothe engine radiator
may beblocked orthe electric engineradiator fanmay be
malfunction ing.
The coolant istoo hotand theengine isno longer beingcooled
sufficiently.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Pull over andstop thevehicle safelyandswitch offthe engine,
payi ngatten tiontoroad andtraffic condition s.
X Allow theengine andcoolant tocool.
X Check thecoolant levelandadd coolant (Ypage 315). Observe
the warning notes.
X Ifyou need toadd coolant moreoften thanusual,have the
engine coolant systemchecked.
X Make surethattheairsupply tothe engine radiator isnot
blocked, e.g.bysnow, slushorice.
X At coolant temperatures under248‡(120 †),drive tothe next
qualified specialist workshop.
X Avo idsubjec tingthe engin etoheavy loads, e.g.driving in
mountainous terrain,andstop- and-go traffic. ?
The
redcoolant
warning lampcomes on
while theengine is
runnin g.Awarning tone
also sounds. The
coolant temperat urehas exceeded 248‡(120 †).The
airflow tothe engine radiator maybeblocked orthe coolant level
may betoo low.
The engine isnot being cooled sufficient lyand may bedamaged.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Pull over andstop thevehicle safelyandswitch offthe engine,
paying attentiontoroad andtraffic conditions.
X Allow theengine andcoolant tocool.
X Check thecoolant levelandadd coolant (Ypage 315). Observe
the warning notes.
X Ifyou need toadd coolant moreoften thanusual ,have the
en gin eco olan tsyst em checke d.
X Mak esur eth at theair supp lyto theen gin eradi ator isno t
bloc ked, e.g. by snow, slushor ice .
X At coolan ttemperatures under248‡(120 †),drive tothe next
qualified specialist workshop.
X Avo idsubjec tingthe engin etoheavy loads, e.g.driving in
mountainous terrain,andstop- and-go traffic. 278
War
ning andindicator lampsin the instru mentclusterOn-board computer and displays