2015 MERCEDES-BENZ CLA-Class check engine light

Engine
Problem
Possible causes/consequences and
M
MSolutions ;
The yellow Check
Engine warning lamp
lights up while the
engine is running.
There may be a malfunction, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system
R in the fuel system
The emission limit values may be exceeded and the engine may be
in emergency mode.
X Have the vehicle checked as soon as possible at a qualified
specialist workshop.
i In some states, you must immediately visit a qualified special-
ist workshop as 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 whether such legal regulations apply in the state in which you are currently driving. æ
The yellow reserve fuel
warning lamp lights up
while the engine is run-
ning.
The fuel level has dropped into the reserve range.
X Refuel at the nearest gas station. æ
The yellow reserve fuel
warning lamp flashes
while the vehicle is in
motion.
In addition, the
;
Check Engine warning
lamp may light up. The fuel system pressure is too low. The fuel filler cap is not closed
correctly or the fuel system is leaking.
X Check that the fuel filler cap is correctly closed.
X If the fuel filler cap is not correctly closed: close the fuel filler
cap.
X If the fuel filler cap is closed: visit a qualified specialist work-
shop. ?
The red coolant warn-
ing lamp lights up while
the engine is running
and the coolant tem-
perature gauge is at the start of the scale. The temperature sensor for the coolant temperature gauge is
defective.
The coolant temperature is no longer being monitored. There is a risk of engine damage if the coolant temperature is too high.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions. Do not continue
driving under any circumstances.
X Secure the vehicle against rolling away (Y page 160).
X Consult a qualified specialist workshop. 256
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions X
Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 289).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in moun-
tainous terrain, and stop-and-go traffic. Driving systems
Problem
Possible causes/consequences and
M MSolutions ·
The red distance warn-
ing lamp lights up while
the vehicle is in motion. A warning tone also
sounds. You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
X Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to
brake or take evasive action.
For further information about the distance warning function of
COLLISION PREVENTION ASSIST PLUS, see (Y page 64).258
Warning and indicator lamps in the instrument clusterOn-board computer and displays

!
Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood. X
Make sure that the windshield wipers are
switched off.
X Pull release lever :on the hood.
The hood is released. X
Reach into the gap between the hood and
the radiator trim and press hood catch
lever ;to the left.
X Raise the hood. X
Pull support strut ?out of bracket A.
X Lift up support strut ?and insert it into
yellow retaining clip =.
Closing the hood X
Raise the hood slightly and, at the same
time, remove support strut ?from yellow
retaining clip =.
X Swing support strut ?down and press it
into bracket Auntil it engages.
X Lower the hood and let it fall from a height
of approximately 8 in (20 cm).
X Check 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 a little 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 a different location.
When checking the oil level:
R park the vehicle on a level surface.
R the engine should be switched off for
approximately five minutes if the engine is
at normal operating temperature.
R if the engine is not at normal operating
temperature, e.g. if the engine was only
started briefly, wait about 30 minutes
before carrying out the measurement. Engine compartment
287Maintenance and care Z

G
WARNING
Battery acid is caustic. There is a risk of injury. Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean over
the battery. Keep children away from batter-
ies. Wash away battery acid immediately with
plenty of clean water and seek medical atten- tion. G
WARNING
A discharged battery can freeze at tempera-
tures below freezing point. When jump-start-
ing 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.
! Only use battery chargers with a maxi-
mum charging voltage of 14.8 V.
! Only
charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment (Y page 309).
X Open the hood.
X Connect the battery charger to the positive
terminal and ground point in the same
order as when connecting the donor bat-
tery in the jump-starting procedure
(Y page 309).
If the indicator/warning lamps do not light up 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. The service life of a
thawed-out battery may be shorter. The start-
ing characteristics can be impaired, particu-
larly at low temperatures. Have the thawed-
out battery checked at a qualified specialist
workshop.
Only charge the installed battery with a bat-
tery charger which has been tested and
approved by Mercedes-Benz. A battery
charger unit specially adapted for Mercedes-
Benz vehicles and tested and approved by Mercedes-Benz is available as an accessory.
It permits the charging of the battery in its
installed position. Contact an authorized
Mercedes-Benz Center for further informa-
tion and availability. Read the battery charg-
er's operating instructions before charging
the battery.308
Battery (vehicle)Roadside Assistance

Jump-starting
For the jump-starting procedure, use only the jump-starting connection point, consisting of a positive terminal and a ground point, in the engine compartment. G
WARNING
Battery acid is caustic. There is a risk of injury.
Avoid contact with skin, eyes or clothing. Do not inhale any battery gases. Do not lean over the
battery. Keep children away from batteries. Wash away battery acid immediately with plenty of
clean water and seek medical attention. 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 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. Jump-starting
309Roadside Assistance Z

X
Start the engine of the donor vehicle and run it at idling speed.
X Connect negative terminal ?of donor battery Bto ground point Aof your vehicle using
the jumper cable, connecting the jumper cable to battery of other vehicle Bfirst.
X If the battery is fully discharged, leave the battery that is being used to jump-start connected
for a few minutes before attempting to start. This charges the battery slightly.
X Start the engine.
X Before disconnecting the jumper cables, let the engine run for several minutes.
X First, remove the jumper cables from ground point Aand negative terminal ?, then from
positive clamp ;and positive terminal =. Begin each time at the contacts on your own
vehicle first.
X Close cover :of positive terminal ;after removing the jumper cables.
X Close the hood.
X Have the battery checked at a qualified specialist workshop.
i Jump-starting is not considered to be a normal operating condition.
i Jumper cables and further information regarding jump-starting can be obtained at any
qualified specialist workshop. Towing and tow-starting
Important safety notes
G
WARNING
Functions relevant to safety are restricted or
no longer available if:
R the engine is not running.
R the brake system or the power steering is
malfunctioning.
R there is a malfunction in the voltage supply
or the vehicle's electrical system.
If your vehicle is being towed, much more
force may be necessary to steer or brake.
There is a risk of an accident.
In such cases, use a tow bar. Before towing,
make sure that the steering moves freely. G
WARNING
You can no longer steer the vehicle if the
steering wheel lock has been engaged. There is a risk of an accident.
Always switch off the ignition when towing the
vehicle with a tow cable or a tow bar. G
WARNING
When towing or tow-starting another vehicle
and its weight is greater than the permissible gross weight of your vehicle, the:
R the towing eye could detach itself
R the vehicle/trailer combination could roll-
over.
There is a risk of an accident.
When towing or tow-starting another vehicle,
its weight should not be greater than the per- missible gross weight of your vehicle.
Details on the permissible gross vehicle
weight of your vehicle can be found on the
vehicle identification plate (Y page 352).
! When COLLISION PREVENTION ASSIST
PLUS, DISTRONIC PLUS or the HOLD func- tion is activated, the vehicle brakes auto-
matically in certain situations. To avoid
damage to the vehicle, deactivate these
systems in the following or similar situa-
tions:
R when towing the vehicle
R in the car wash Towing and tow-starting
311Roadside Assistance Z