2015 MERCEDES-BENZ S-Class ECU

SmartKey
Display messages
Possible causes/consequences and
M
MSolutions Â
Key Does Not Key Does Not
Belong to Vehicle Belong to Vehicle You have put the wrong SmartKey in the ignition lock.
X Use the correct SmartKey. Â
Take Take
Your
YourKey
Keyfrom
from
Ignition
Ignition The SmartKey is in the ignition lock.
X Remove the SmartKey. Â
Obtain a New Key Obtain a New Key The SmartKey needs to be replaced.
X Visit a qualified specialist workshop. Â
Replace Replace
Key
KeyBattery
Battery The SmartKey batteries are discharged.
X Change the batteries (Y page 94).Â
Don't Forget Your Don't Forget Your
Key Key The SmartKey is not in the ignition lock. You have opened the
driver's door with the engine switched off.
This display message is displayed for a maximum of 60 seconds
and is simply a reminder.
X Take the SmartKey with you when you leave the vehicle. Â
Key Not Detected Key Not Detected
(white display mes-
sage) The SmartKey is currently undetected.
X Change the location of the SmartKey in the vehicle.
If the SmartKey still cannot be detected:
X Insert the SmartKey into the ignition lock and turn it to the
desired position. Â
Key Not Detected Key Not Detected
(red display message) The SmartKey is not in the vehicle.
A warning tone also sounds.
If the engine is switched off, you can no longer lock the vehicle
centrally or start the engine.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 220).
X Locate the SmartKey.
X Press aon the steering wheel to confirm the display mes-
sage. 354
Display messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Because there is interference from a strong source of radio waves,
the key is not detected whilst the engine is running.
A warning tone also sounds.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 220).
X Insert the SmartKey into the ignition lock and bring into key
mode. Â
Remove Remove
'Start'
'Start' But‐
But‐
ton and Insert Key
ton and Insert Key The SmartKey is continually undetected.
The SmartKey detection function has a temporary malfunction or
is faulty. A warning tone also sounds.
X Insert the SmartKey into the ignition lock and turn it to the
desired position.
X Visit a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
Safety
Seat belts Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ü
N
After starting the engine, the red seat belt warning lamp lights up for
6 seconds.
The seat belt warning lamp reminds the driver and front passenger to fasten
their seat belts.
X Fasten your seat belt (Y page 54).ü
N
After starting the engine, the red seat belt warning lamp lights up. In addi-
tion, a warning tone sounds for up to 6 seconds.
The driver's seat belt is not fastened.
X Fasten your seat belt (Y page 54).
The warning tone ceases. Wa
rning and indi cator lamps in the instrument cluster
355On-board computer and displays Z

Warning/
indicator
lamp
N
N Signal type
Possible causes/consequences and M MSolutions ü
N
The red seat belt warning lamp lights up after the engine starts, as soon as
the driver's or the front-passenger door is closed.
The driver or front passenger has not fastened their seat belt.
X Fasten your seat belt (Y page 54).
The warning lamp goes out.
There are objects on the front-passenger seat. X Remove the objects from the front-passenger seat and stow them in a
secure place.
The warning lamp goes out. ü
N
The red seat belt warning lamp flashes and an intermittent audible warning
sounds.
The driver or front passenger has not fastened their seat belt. The vehicle is
being driven faster than 15 mph (25 km/h) or has briefly been driven faster
than 15 mph (25 km/h).
X Fasten your seat belt (Y page 54).
The warning lamp goes out and the intermittent warning tone ceases.
There are objects on the front-passenger seat. The vehicle is being driven
faster than 15 mph (25 km/h) or has briefly been driven faster than 15 mph
(25 km/h).
X Remove the objects from the front-passenger seat and stow them in a
secure place.
The warning lamp goes out and the intermittent warning tone ceases. 356
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Safety systems
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions $J
N
$ (USA only), J(Canada only): the red brake system warning lamp
is lit while the engine is running. A warning tone also sounds.
G WARNING
The brake boosting effect is malfunctioning and the braking characteristics
may be affected.
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 circumstan-
ces.
X Secure the vehicle against rolling away (Y page 220).
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. $J
N
$ (USA only), J(Canada only): the red brake system warning lamp
is lit while the engine is running. A warning tone also sounds.
There is not enough brake fluid in the brake fluid reservoir.
G WARNING
The braking effect 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 circumstan-
ces.
X Secure the vehicle against rolling away (Y page 220).
X Do not add brake fluid. Adding more will not remedy the malfunction.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. $
N
USA only: the red brake system warning lamp is lit while the engine is
running. The multifunction display also shows a display message with the
# symbol.
The brake pads/linings have reached their wear limit.
X Visit a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
357On-board computer and displays Z

Warning/
indicator
lamp
N
N Signal type
Possible causes/consequences and M MSolutions ?
N
The red coolant warning lamp lights up while the engine is running and the
coolant temperature gage is at the start of the bar display.
The temperature sensor for the coolant temperature gage 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 220).
X Consult a qualified specialist workshop. 364
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ?
N
The red coolant warning lamp comes on while the engine is running.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may be blocked
or the electric engine radiator fan may be malfunctioning.
The coolant is too hot and the engine is no longer being cooled sufficiently.
X Observe the additional display messages in the multifunction display.
X Pull over and stop the vehicle safely and switch off the engine, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 220).
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 408).
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 Do not start the engine again until the coolant temperature is below 257 ‡
(125 †). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in mountainous
terrain, and stop-and-go traffic. ?
N
The red coolant warning lamp comes on while the engine is running. A
warning tone also sounds.
The coolant temperature has exceeded 255 ‡ (124 †). The airflow to the
engine radiator may be blocked or the coolant level may be too low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when your engine is overheated. This can cause some fluids which may have leaked into the engine compartment to catch fire.
Steam from the overheated engine can also cause serious burns which can
occur just by opening the hood.
There is a risk of injury.
X Observe the additional display messages in the multifunction display.
X Pull over and stop the vehicle safely and switch off the engine, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 220).Warning and indicator lamps in the instrument cluster
365On-board computer and displays Z

Warning/
indicator
lamp
N
N Signal type
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 408).
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 257 ‡(125 †), you can continue driving to
the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in mountainous
terrain, and stop-and-go traffic. Hybrid system
Warning/
indicator
lamp
N
N Signal type
Possible causes/consequences and M MSolutions é
N
The yellow RBS (recuperative brake system) warning lamp is on. In addition,
there may be a warning tone.
G Risk of accident
RBS is malfunctioning. Pedal travel may be longer than usual and braking
performance may be affected. The automatic engine switch-off function may also be deactivated.
X Observe the messages in the multifunction display (Y page 316).
X Drive on carefully.
X Visit a qualified specialist workshop. 366
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Tires
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions h
N
The yellow tire pressure monitor warning lamp (pressure loss/malfunction)
is lit.
The tire pressure monitor has detected a loss of pressure in at least one of the
tires.
G WARNING
With tire pressures which are too low, there is a risk of the following hazards:
R they may burst, especially as the load and vehicle speed increase.
R they may wear excessively and/or unevenly, which may greatly impair tire
traction.
R the driving characteristics, as well as steering and braking, may be greatly
impaired.
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking maneuvers.
Pay attention to the traffic conditions as you do so.
X Secure the vehicle against rolling away (Y page 220).
X Observe the additional display messages in the multifunction display.
X Check the tires and, if necessary, follow the instructions for a flat tire
(Y page 423).
X Check the tire pressure (Y page 449).
X If necessary, correct the tire pressure. h
N
The yellow tire pressure monitor warning lamp (pressure loss/malfunction)
flashes for approximately one minute and then remains lit.
The tire pressure monitor is faulty.
G WARNING
The system is possibly unable to recognize or register low tire pressure.
There is a risk of an accident.
X Observe the additional display messages in the multifunction display.
X Visit a qualified specialist workshop. 368
Warning and indicator lamps in the instrument clusterOn-board computer and displays