check engine light MERCEDES-BENZ A-CLASS HATCHBACK 2015 User Guide

Problems with the seat heating
Problem
Possible causes/consequences and
M
MSolutions The seat heating has
switched off prema-
turely or cannot be
switched on. The on-board voltage is too low because too many electrical con-
sumers are switched on.
X Switch off electrical consumers that you do not need, such as
the rear window heating or interior lighting.
Once the battery is sufficiently charged, the seat heating will
switch back on automatically. Steering wheel
Important safety notes
G
WARNING
You could lose control of the vehicle while
driving if you:
R adjust the driver's seat, steering wheel or
mirrors
R fasten the seat belt
There is a risk of an accident.
Adjust the driver's seat, head restraint, steer-
ing wheel and mirrors and fasten your seat
belt before starting the engine. G
WARNING
Children could become trapped by the steer-
ing wheel if they adjust it. There is a risk of
injury.
When leaving the vehicle, always take the key with you and lock the vehicle. Never leave
children unattended in the vehicle. Adjusting the steering wheel
G
WARNING
The steering wheel may move unexpectedly if you adjust it while driving. This could cause
you to lose control of the vehicle. There is a
risk of an accident.
Make sure that the steering wheel is locked
before driving off. Never unlock the steering
wheel when the vehicle is in motion. :
Release lever
; Adjusts the steering wheel height
= Adjusts the steering wheel position (fore-
and-aft adjustment)
X Push release lever :down completely.
The steering column is unlocked.
X Adjust the steering wheel to the desired
position.
X Push release lever :up as far as it will go.
The steering column is locked.
X Check if the steering column is locked.
When doing so, try to push the steering
wheel up or down or try to move it in the
fore-and-aft direction. 112
Steering wheelSeats, steering wheel and mirrors

Problem
Possible causes/consequences and
M
MSolutions Vehicles with a petrol
engine:
The engine is not run-
ning smoothly and is
misfiring. There is a malfunction in the engine electronics or in a mechanical
component of the engine management system.
X Only depress the accelerator pedal slightly.
Otherwise, non-combusted fuel may get into the catalytic con-
verter and damage it.
X Have the cause rectified immediately at a qualified specialist
workshop. The coolant tempera-
ture display is showing
more than 120 †. The
coolant warning lamp
may also be on and a
warning tone may
sound. The coolant level is too low. The coolant is too hot and the engine
is no longer being cooled sufficiently.
X Stop as soon as possible and allow the engine and the coolant to
cool down.
X Check the coolant level (Y page 326). Observe the warning
notes as you do so and top up the coolant if necessary. If the coolant level is correct, the engine radiator fan may be faulty.
The coolant is too hot and the engine is no longer being cooled
sufficiently.
X If the coolant temperature is below 120 †, you can continue
driving to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in
mountainous terrain and stop-start traffic. DYNAMIC SELECT button (all vehicles
except Mercedes-AMG vehicles)
Use the DYNAMIC SELECT button to change
the drive program. Depending on the drive
program selected, the following vehicle char- acteristics will change:
R the drive (engine and transmission man-
agement)
R the suspension (vehicles with damping sys-
tem or AMG RIDE CONTROL)
R the steering
R the availability of the ECO start/stop func-
tion
R the climate control
If the ignition is switched off for less than four hours, the previously selected drive program
is activated when the engine is next started. If the ignition is switched off for more than four hours, drive program
Cis activated when the
engine is next started. X
Press DYNAMIC SELECT controller :as
many times as necessary until the desired
drive program is selected.
The selected drive program appears in the
multifunction display. After five seconds
the display goes out and the status icon of the selected drive program appears. 166
DYNAMIC SELECT button (all vehicles except Mercedes-AMG vehicles)Driving and parking

The function of the electric parking brake is
dependent on the on-board voltage. If the on-
board voltage is low or if there is a malfunc-
tion in the system, it may not be possible to
apply the released parking brake.
X If this is the case, only park the vehicle on
level ground and secure it to prevent it from
rolling away.
X Vehicles with automatic transmission:
shift the automatic transmission to posi-
tion P.
X Vehicles with manual transmission:
engage first gear.
It may not be possible to release an applied
parking brake if the on-board voltage is low or
if there is a malfunction in the system. Con-
tact a qualified specialist workshop.
The electric parking brake carries out a func-
tion check at regular intervals when the
engine is switched off. Noises that occur are
normal.
Applying or releasing manually X
To apply: push handle :.
When the electric parking brake is applied, the ! red indicator lamp lights up in the
instrument cluster.
The electric parking brake can also be
applied when the key is removed.
X To release: pull handle:.
The red !indicator lamp in the instru-
ment cluster goes out. The electric parking brake can only be
released:
R when the key is in position 1or 2in the
ignition lock (Y page 157) or
R if the ignition was switched on using the
Start/Stop button
Applying automatically (vehicles with
automatic transmission) The electric parking brake is automatically
applied when the transmission is in position P
and:
R the engine is switched off or
R the driver is not wearing a seat belt and the
driver's door is opened
To prevent the electric parking brake from
being automatically applied, pull handle :.
The electric parking brake is also engaged
automatically if:
R DISTRONIC PLUS brings the vehicle to a
standstill or
R the HOLD function is keeping the vehicle
stationary
R Active Parking Assist is keeping the vehicle
stationary
In addition, at least one of the following con-
ditions must be fulfilled:
R there is a system malfunction
R the power supply is insufficient
R the vehicle is stationary for a lengthy period
The red !indicator lamp in the instrument
cluster lights up.
The electric parking brake is not automati-
cally applied if the engine is switched off by
the ECO start/stop function.
Applying automatically (vehicles with
manual transmission) When the vehicle's HOLD function is holding
the vehicle at a standstill, the electric parking
brake is applied automatically. 186
ParkingDriving and parking

of the braking effect of the engine. This
relieves the load on the brake system and
prevents the brakes from overheating and
wearing too quickly.
Use cruise control only if road and traffic con- ditions are appropriate for maintaining a
steady speed for a prolonged period. You can
store any road speed above 30 km/h.
The speed indicated in the speedometer may differ slightly from the speed stored.
Important safety notes If you fail to adapt your driving style, cruise
control can neither reduce the risk of an acci-
dent nor override the laws of physics. Cruise
control cannot take into account road,
weather or traffic conditions. Cruise control is only an aid. You are responsible for the dis-
tance to the vehicle in front, for vehicle speed,
for braking in good time, and for staying in
lane.
Do not use cruise control:
R in road and traffic conditions which do not
allow you to maintain a constant speed, e.g.
in heavy traffic or on winding roads
R on smooth or slippery roads. Braking or
accelerating can cause the drive wheels to lose traction and the vehicle could then
skid
R when there is poor visibility, e.g. due to fog,
heavy rain or snow
If there is a change of drivers, advise the new
driver of the speed stored. Cruise control lever :
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control
You can operate cruise control and variable
SPEEDTRONIC with the cruise control lever.
The LIM indicator lamp on the cruise control
lever indicates which system you have selec- ted:
R LIM indicator lamp off: cruise control is
selected
R LIM indicator lamp on: variable SPEED-
TRONIC is selected
When you activate cruise control, the stored
speed is shown in the multifunction display
for five seconds.
Selecting cruise control X
To select cruise control: check whether
LIM indicator lamp ;is on or off.
If it is off, cruise control is already selected.
X If it is not, press the cruise control lever in
the direction of arrow A.
LIM indicator lamp ;in the cruise control
lever goes out. Cruise control is selected. 192
Driving systemsDriving and parking

Variable SPEEDTRONIC
General notes
:
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control
With the cruise control lever, you can operate
cruise control or DISTRONIC PLUS and vari-
able SPEEDTRONIC.
The LIM indicator lamp on the cruise control
lever indicates which system you have selec- ted:
R LIM indicator lamp off: cruise control or
DISTRONIC PLUS is selected
R LIM indicator lamp on: variable SPEED-
TRONIC is selected
When the engine is running, you can use the
cruise control lever to limit the speed to any
speed between 30 km/h and the technically
permitted maximum speed of the vehicle. If
the set value of permanent SPEEDTRONIC is
lower then this value applies (Y page 196).
Selecting variable SPEEDTRONIC X Check whether LIM indicator lamp ;is on.
If it is on, variable SPEEDTRONIC is already selected. If it is not, press the cruise control lever in
the direction of arrow
A.
LIM indicator lamp ;in the cruise control
lever lights up. Variable SPEEDTRONIC is
selected.
Storing the current speed
You can use the cruise control lever to limit
the speed to any speed above 30 km/h while
the engine is running.
X Briefly press the cruise control lever up :
or down ?.
The current speed is stored and shown in
the multifunction display.
Storing or calling up the speed G
WARNING
If you call up the stored speed and it is lower
than the current speed, the vehicle deceler-
ates. If you do not know the stored speed, the vehicle could decelerate unexpectedly. There
is a risk of an accident.
Pay attention to the road and traffic condi-
tions before calling up the stored speed. If you do not know the stored speed, store the
desired speed again.
X Briefly pull the cruise control lever towards
you =.
Setting a speed X To adjust the set speed in 10 km/h
increments: briefly press the cruise con-
trol lever up :beyond the pressure point
for a higher speed, or down ?for a lower
speed.
or X Keep the cruise control lever pressed
beyond the pressure point until the desired
speed is set. Press the cruise control lever
up : for a higher speed or down ?for a
lower speed.
X To adjust the set speed in 1 km/h incre-
ments: briefly press the cruise control Driving systems
195Driving and parking Z

Activating Blind Spot Assist
X Make sure that Blind Spot Assist is activa-
ted in the on-board computer
(Y page 249).
X Turn the key to position 2in the ignition
lock.
Warning lamps :in the exterior mirrors
light up red for approximately 1.5 seconds
and then turn yellow.
Towing a trailer
If you couple up a trailer, make sure that you have correctly established the electrical con-
nection. This can be accomplished by check- ing the trailer lighting. Blind Spot Assist is
then deactivated. The indicator lamps in the
exterior mirrors light up yellow and the
Blind
Blind Spot SpotAssist
Assist not
notavailable
available when
when
towing a trailer See Owner's Manual
towing a trailer See Owner's Manual
message appears in the multifunction dis-
play.
i You can deactivate the indicator lamps in
the exterior mirrors.
To do so, you will need to deactivate Blind
Spot Assist if:
R the key is in position 2in the ignition lock
R the engine is not running
R the electrical connection to the trailer
has been established
Lane Keeping Assist General notes
Lane Keeping Assist monitors the area in
front of your vehicle by means of multifunc- tion camera
:attached at the top of the
windscreen. Lane Keeping Assist detects lane markings on the road and can warn you
before you leave your lane unintentionally.
This function is available in a speed range
between 60 km/h and 200 km/h.
A warning may be given if a front wheel
passes over a lane marking. It will warn you by
means of intermittent vibration through the
steering wheel for up to 1.5 seconds.
Important safety notes G
WARNING
Lane Keeping Assist cannot always clearly
identify lane markings.
In these cases, Lane Keeping Assist may:
R give an unnecessary warning
R not give a warning
There is a risk of an accident.
Always pay particular attention to the traffic
situation and keep in lane, especially if Lane
Keeping Assist alerts you. G
WARNING
The Lane Keeping Assist warning does not
return the vehicle to the original lane. There is a risk of an accident.
Always steer, apply the brakes or accelerate
the vehicle yourself, especially if Lane Keep-
ing Assist alerts you.
If you fail to adapt your driving style, Lane
Keeping Assist can neither reduce the risk of
an accident nor override the laws of physics. Lane Keeping Assist cannot take into account
road, weather or traffic conditions. Lane
Keeping Assist is only an aid. You are respon- sible for the distance to the vehicle in front,
for vehicle speed, for braking in good time and
for staying in lane.
Lane Keeping Assist does not keep your vehi- cle in its lane. 228
Driving systemsDriving and pa
rking

Display messages
Possible causes/consequences and
M
MSolutions J
Check brake fluid Check brake fluid
level level There is insufficient brake fluid in the brake fluid reservoir.
In addition, the red Jwarning lamp lights up in the instrument
cluster and a warning tone sounds.
G WARNING
Braking efficiency may be impaired.
There is a risk of an accident. X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Safeguard the vehicle against rolling away (Y page 184).
X Consult a qualified specialist workshop.
X Do not top up the brake fluid. This does not correct the fault. #
Check brake pad Check brake pad
wear wear The brake pads/linings have reached their wear limit.
X Consult a qualified specialist workshop. G
Inoperative
Inoperative One or more main features of the Mercedes-Benz Contact system
are malfunctioning.
X Consult a qualified specialist workshop. Collision Preven‐
Collision Preven‐
tion Assist Plus tion Assist Plus
currently unavail‐ currently unavail‐
able See Owner's able See Owner's
Manual Manual COLLISION PREVENTION ASSIST PLUS is temporarily inoperative.
Possible causes:
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation
R the system is outside the operating temperature range
R the on-board voltage is too low.
Once the causes listed above no longer apply, the display message goes out.
COLLISION PREVENTION ASSIST PLUS is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Safeguard the vehicle against rolling away (Y page 184).
X Restart the engine. Collision Preven‐ Collision Preven‐
tion Assist Plus tion Assist Plus
inoperative inoperative COLLISION PREVENTION ASSIST PLUS is temporarily inoperative
due to a malfunction. Adaptive Brake Assist may also have failed.
X Consult a qualified specialist workshop immediately. Display
messages
265On-board computer/Displays Z

Display messages
Possible causes/consequences and
M
MSolutions Ð
Power Power
steering
steering mal‐
mal‐
function See Own‐
function See Own‐
er's Manual er's Manual The power steering assistance is faulty.
A warning tone also sounds.
G WARNING
You will need to use more force to steer.
There is a risk of an accident. X Check whether you are able to apply the extra force required.
If you are able to steer safely: X Drive on carefully.
X Consult a qualified specialist workshop immediately.
If you are unable to steer safely:
X Do not drive on.
X Consult a qualified specialist workshop. Ð
Steering malfunc‐ Steering malfunc‐
tion See Owner's tion See Owner's
Manual Manual The electric steering lock is malfunctioning.
G WARNING
The steering may be locked by the electric steering lock.
There is a risk of an accident. X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Safeguard the vehicle against rolling away (Y page 184).
X Do not drive on.
X Consult a qualified specialist workshop. _
Before starting Before starting
the engine, turn the engine, turn
the the
steering
steering wheel.
wheel. The electric steering lock was unable to unlock the steering.
X Remove the key from the ignition lock.
X To unlock the steering, move the steering wheel slightly.
X Insert the key into the ignition lock again. Telephone No ser‐
Telephone No ser‐
vice vice Your vehicle is outside the network provider's transmitter/
receiver range.
X Wait until the mobile phone operational readiness symbol
appears in the multifunction display. ¥
Top Top
up
upwasher
washer fluid
fluid The washer fluid level in the washer fluid reservoir has dropped
below the minimum.
X Top up the washer fluid (Y page 327).290
Display
messagesOn-board computer/Displays

Engine
Problem
Possible causes/consequences and
M
MSolutions ;
The yellow engine diag-
nostics warning lamp
lights up while the
engine is running. There may be a fault, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with petrol engines)
R in the fuel system
The emission limit values may be exceeded and the engine may be running in emergency mode.
X Consult a qualified specialist workshop immediately. Vehicles with a diesel engine: the fuel tank has been run dry
(Y
page 183).
X Start the engine three to four times after refuelling.
If the yellow engine diagnostics warning lamp goes out, emer-
gency running mode is cancelled. The vehicle need not be
checked. æ
The yellow reserve fuel
warning lamp is on
while the engine is run-
ning.
The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if the fuel level
drops into the reserve range.
X Refuel at the nearest filling station. ?
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
faulty.
The coolant temperature is no longer being monitored. There is a risk of engine damage if the coolant temperature is too high.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine. Do not continue driving
under any circumstances.
X Safeguard the vehicle against rolling away (Y page 184).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
301On-board computer/Displays Z

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 top up the coolant, observing the
warning notes (Y page 326).
X If you have to top up the coolant frequently, have the engine
cooling system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X If the coolant temperature is below 120 †, you can continue
driving to the nearest qualified specialist workshop.
X Avoid putting the engine under heavy load as you do so, e.g.
driving in mountainous terrain and stop-start traffic. Driving systems
Problem
Possible causes/consequences and
M MSolutions ·
The red distance warn-
ing lamp lights up while
the vehicle is in motion. The distance to the vehicle in front is too small for the speed
selected.
X Increase the distance. ·
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 on the distance warning function of COL-
LISION PREVENTION ASSIST PLUS, see (Y page 70).Warning and indicator lamps in the instrument cluster
303On-board computer/Displays Z