378 Practical hintsWhat to do if …Symbol messagesDisplay symbol
Display messages
Possible cause
Possible solution
#
Undervoltage
Switch off
consumers
The battery has insufficient voltage.
Turn off unnecessary electrical con-
sumers.
Visit workshop
The battery is no longer charging.
Possible causes:
alternator malfunctioning
broken poly-V-belt
Do not forget that the brake system re-
quires electrical energy and may be oper-
ating with restricted capability. 
Considerably greater brake pedal force is 
required and the stopping distance is in-
creased.
Stop immediately and check the 
poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise 
the engine will overheat due to an in-
operative water pump which may re-
sult in damage to the engine. Notify 
an authorized Mercedes-Benz Center.
If it is intact:
Drive immediately to the nearest au-
thorized Mercedes-Benz Center. Ad-
just driving to be consistent with 
reduced braking responsiveness. 
385 Practical hints
What to do if …
Display symbol
Display messages
Possible cause
Possible solution
Ï 
Coolant
Stop, engine off
The poly-V-belt could be broken.
Stop immediately and check the 
poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise 
the engine will overheat due to an in-
operative water pump which may re-
sult in damage to the engine. Notify 
an authorized Mercedes-Benz Center.
If it is intact:
Do not continue to drive the vehicle 
with this message displayed. Doing so 
could result in serious engine damage 
that is not covered by the 
Mercedes-Benz Warranty.
Drive immediately to the nearest au-
thorized Mercedes-Benz Center.
Coolant
Visit workshop
The cooling fan for the coolant is malfunc-
tioning.
Observe the coolant temperature dis-
play.
Have the fan replaced as soon as pos-
sible. 
466 Technical dataFuels, coolants, lubricants etc.Fuel requirements
Gasoline engine
Only use premium unleaded gasoline 
meeting ASTM standard D 439.
The octane number (posted at the pump) 
must be 91 “min”. It is an average of both 
the Research (R) Octane Number and the 
Motor (M) Octane Number: (R+M)/2). This 
is also known as the ANTI-KNOCK INDEX.
Unleaded gasoline containing oxygenates 
such as ethanol, IPA, IBA and TBA can be 
used provided the ratio of any one of these 
oxygenates to gasoline does not exceed 
10%; MTBE must not exceed 15%.
The ratio of methanol to gasoline must not 
exceed 3% plus additional cosolvents.
Using mixtures of ethanol and methanol is 
not allowed. Gasohol, which contains 10% 
ethanol and 90% unleaded gasoline, can be 
used.
These blends must also meet all other fuel 
requirements, such as resistance to spark 
knock, boiling range, vapor pressure, etc.Diesel engine
Only use commercially available vehicular 
diesel fuels No. 2 or No. 1 (ASTM D975 
No.2-D or No.1-D). 
To prevent malfunctions, diesel fuel with 
better cold flow quality is offered in the 
winter months. Check with your fuel 
retailer.
Coolants
The engine coolant is a mixture of water 
and anticorrosion/antifreeze, which pro-
vides:
Corrosion protection
Freeze protection
Boiling protection (by increasing the 
boiling point)
The cooling system was filled at the factory 
with a coolant providing freeze protection 
to approximately -22°F (-30°C) and corro-
sion protection.
!Do not fill the tank with gasoline. Do 
not mix diesel fuel with gasoline or ker-
osene. The fuel system and engine will 
otherwise be damaged, which is not 
covered by the Mercedes-Benz Limited 
Warranty.