Get Practical advice -> Troubleshooting Guide for Mercedes A Class 4 Door Second Generation (2004-2011)

Practical advice

Troubleshooting

Points to remember

G Risk of accident and injury

If maintenance work is carried out incorrectly this can jeopardise the operating safety of your vehicle. You risk losing control of your vehicle

and thereby causing an accident. The safety systems may also no longer be able to protect you or others as they are designed to do.

Always have maintenance work carried out at a qualified specialist workshop which has the necessary specialist knowledge and tools to

carry out the work required.

Mercedes-Benz recommends that you use a Mercedes-Benz Service Centre for this purpose.

In particular, all work relevant to safety or on safety-related systems must be carried out at a qualified specialist workshop.

Warning and indicator lamps in switches and buttons

Problem

Possible cause/consequence

Suggested solutions

One or all of the indicator lamps

The on-board voltage is too low,

X Switch off consumers that are not required, e. g. reading lamp or

because too many consumers are

interior lighting.

in the seat heating* button are

switched on.

Once the battery is sufficiently charged, the seat ventilation* will

flashing. The seat heating* has

switch back on automatically.

switched itself off automatically.

The indicator lamp in the 2

Cooling has been deactivated

X Visit a qualified specialist workshop.

button on the air-conditioning*/ due to a malfunction.

Thermotronic* control panel

lights up. The cooling system can-

not be switched on.

* optional

222

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

The indicator lamp in the F/ The on-board voltage is too low,

X Switch off consumers that are not required, e. g. reading lamp or

1 rear-window heating button because too many consumers are

interior lighting.

is flashing. The rear-window heat- switched on.

Once the battery is sufficiently charged, the rear window heating

will switch back on automatically.

ing has switched itself off prema-

turely or cannot be switched on.

Vehicles with automatic child

A special Mercedes-Benz child

seat recognition on the front-

seat with automatic child seat

passenger seat:

recognition has been fitted to the

front-passenger seat. The front-

The 5 PASSENGER AIRBAG

passenger airbag has therefore

OFF warning lamp on the centre

been disabled as desired.

console is lit.

G Risk of injury

X Remove electronic equipment from the front-passenger seat, for

example

There is no child seat fitted to the

R notebook

front-passenger seat. The auto-

matic child seat recognition is

R mobile phone

malfunctioning.

R cards with transponders, e.g. ski passes or access passes

If the 5 PASSENGER AIRBAG OFF warning lamp is still lit:

X Visit a qualified specialist workshop.

You have started the engine with

You have deactivated the ECO

X Activate the ECO start/stop function* again.

the key. The indicator lamp in the

start/stop function*.

ECO start/stop function* button

X Visit a qualified specialist workshop.

The ECO start/stop function*is

does not light up or goes out

not available due to a fault.

again after a short time.

* optional

223

Practical advice

Troubleshooting

Warning and indicator lamps in the instrument cluster

Problem

Possible cause/consequence

Suggested solutions

- The yellow ABS warning

G Risk of accident

X Drive on carefully.

lamp comes on while the

X Observe the additional messages in the multi-function display

ABS (Anti-lock Brake System) is

engine is running.

( Y page 202).

deactivated due to a fault. There-

X Visit a qualified specialist workshop.

fore, ESP ® (Electronic Stability

Program), BAS (Brake Assist), the

steering assistant STEER CON-

TROL, the hill start assist and the

tyre pressure loss warning sys-

tem are also deactivated.

The brake system continues to

function normally, but without

electronic support. The wheels

could therefore lock if you brake

hard.

If the ABS control unit is faulty,

other systems may also not be

available: e.g. Parktronic sys-

tem*, the navigation system* or

the Autotronic*.

- The yellow ABS warning

G Risk of accident

X Switch off consumers that are not required, e g. reading lamps or

lamp comes on while the

interior lighting.

The on-board voltage is too low.

engine is running.

ABS will be available again as soon as the vehicle's electrical sys-

ABS has been deactivated due to

tem voltage increases.

undervoltage.

* optional

224

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

Therefore, ESP ® , BAS, the steer-

ing assistant STEER CONTROL,

hill start assist and the tyre pres-

sure loss warning system are also

deactivated.

The brake system continues to

function normally, but without

electronic support. The wheels

could therefore lock if you brake

hard.

G Risk of accident

X Observe the additional messages in the multi-function display

v The yellow ESP ® warning

( Y page 202).

lamp is lit while the engine

ESP ® is unavailable due to a mal-

is running. In addition, a

X Drive on carefully.

function.

message appears in the

X Visit a qualified specialist workshop.

The following systems have also

multi-function display.

been deactivated:

R BAS

R the steering assistant STEER

CONTROL

R hill start assist

R the tyre pressure loss warning

system

The braking system remains

available with full brake boosting

effect but without the above func-

tions.

225

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

G Risk of accident

X Only depress the accelerator pedal as far as necessary when pull-

v The yellow ESP ® warning

ing away.

lamp flashes while the

ESP ® or traction control has

vehicle is in motion.

X Release the accelerator pedal while you are driving.

intervened because there is a risk

X Adapt your driving style to suit the road and weather conditions.

of skidding or at least one wheel

has started to spin.

X Do not deactivate ESP ® .

1 The red SRS warning lamp G Risk of injury

X Visit a qualified specialist workshop immediately.

is lit while the engine is

There is a malfunction in the

running.

restraint system. The airbags or

belt tensioners may either be trig-

gered unintentionally or, in the

event of an accident, not be trig-

gered at all.

1 The red SRS warning lamp The connector on the removable

X Attach the connector to the coupling on the seat ( Y page 156).

is lit while the engine is

front-passenger seat* is

running. In addition, the

detached.

indicator lamp 5

PASSENGER AIRBAG OFF

flashes in the centre con-

sole and a warning tone

sounds.

H The red brake system

You are driving with the parking

X Release the parking brake.

warning lamp comes on

brake applied.

The warning lamp goes out and the warning tone ceases.

while you are driving. A

warning tone also sounds.

* optional

226

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

H The red brake system

G Risk of accident

X Pull over and stop the vehicle safely, paying attention to road and

warning lamp comes on

traffic conditions. Do not continue driving under any circumstan-

There is insufficient brake fluid in

while the engine is run-

ces.

the fluid reservoir.

ning.

X Consult a qualified specialist workshop immediately.

X Observe the additional messages in the multi-function display

( Y page 202).

Do not top up the brake fluid. This will not rectify the fault.

± The yellow engine diagnos- Vehicles with a diesel engine: the

X Start the engine three to four times after refuelling.

tics warning lamp lights up fuel tank has been run dry.

Emergency running mode is cancelled. The vehicle need not be

while the engine is run-

checked.

ning.

± The yellow engine diagnos- There may be a fault, for example

X Have the vehicle checked as soon as possible at a qualified spe-

tics warning lamp lights up R in the engine management

cialist workshop.

while the engine is run-

R in the ignition system

ning.

R in the exhaust system

R in the ignition system (for vehi-

cles with petrol engines)

The emission limit values may be

exceeded and the engine can run

in emergency mode.

227

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

< The red seat belt warning

The seat belt warning lamp

X Fasten your seat belt ( Y page 73).

lamp lights up for 6 sec-

reminds the driver and front

onds after the engine

passenger to fasten their seat

belts.

starts up 28 .

< After the engine starts, a

G Risk of injury

X Fasten your seat belt ( Y page 73).

warning tone sounds for

The warning tone ceases.

The driver's seat belt is not fas-

up to 6 seconds 28 .

tened.

< The red seat belt warning

G Risk of injury

X Fasten your seat belt ( Y page 73).

lamp lights up after the

The warning lamp goes out.

The driver or front passenger has

engine starts, as soon as

not fastened their seat belt

the driver's door or the

front-passenger door is

G Risk of injury

X Remove the objects from the front-passenger seat and stow them

closed.

safely.

There are objects on the front-

The warning lamp goes out.

passenger seat

28 Only for certain countries.

228

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

< The red warning lamp

G Risk of injury

X Fasten your seat belt ( Y page 73).

flashes and an intermit-

The warning lamp goes out and the intermittent audible warning

The driver or front passenger has

tent audible warning

ceases.

not fastened their seat belt and

sounds.

you are driving faster than

25 km/h or have briefly driven

faster than 25 km/h.

G Risk of injury

X Remove the objects from the front-passenger seat and stow them

safely.

There are objects on the front-

The warning lamp goes out and the intermittent audible warning

passenger seat and you are driv-

ceases.

ing faster than 25 km/h or have

briefly driven faster than

25 km/h.

The yellow engine diagnostics

The fuel level has fallen below the

X Refuel at the nearest filling station.

warning lamp lights up while the

reserve range.

engine is running.

229

Practical advice

Troubleshooting

Warning tones

Problem

Possible cause/consequence

Suggested solutions

You have opened the vehicle with

X Switch off the alarm ( Y page 57).

The anti-theft warning alarm* is

the anti-theft alarm system still

triggered.

activated*.

You hear a warning tone.

A message appears in the multi-

X See the explanations for the display message ( Y page 202).

function display.

You are driving with the parking

X Release the parking brake.

brake applied.

The light is switched on when you X Turn the light switch to M or U.

leave the vehicle.

X If the rear foglamp is switched on: press the light switch in to the

stop.

G Risk of injury

X Fasten your seat belt ( Y page 73).

The driver or front passenger has

not fastened their seat belt

* optional

230

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

X Move the selector lever to P.

You hear a warning tone.

Vehicles with AUTOTRONIC*:

You have:

R switched off the engine

R opened the driver's door

R not moved the selector lever to

position P

Accident

Problem

Possible cause/consequence

Suggested solutions

Fuel is leaking from the vehicle.

G Risk of fire

X Switch off the ignition immediately.

The fuel line or the fuel tank has X Remove the ignition key.

been damaged. The leaking fuel Do not restart the engine under any circumstances. The leaking fuel

creates a risk of fire or explosion. creates a risk of fire or explosion.

X Consult a qualified specialist workshop.

You are unable to determine the

X Consult a qualified specialist workshop.

extent of the damage.

You cannot detect any damage.

X Start the engine as normal.

* optional

231

Practical advice

Troubleshooting

Fuel and fuel tank

Problem

Possible cause/consequence

Suggested solutions

X Turn the key to position 0 ( Y page 62) in the ignition lock immedi-

Fuel is leaking from the vehicle.

G Risk of explosion or fire

ately and remove it.

The fuel line or the fuel tank is

X Do not restart the engine under any circumstances.

defective.

X Consult a qualified specialist workshop.

The fuel filler flap cannot be

The fuel filler flap is not released.

X Unlock the vehicle ( Y page 241).

opened.

X Unlock the vehicle manually ( Y page 242).

The opening mechanism is jam-

X Consult a qualified specialist workshop.

med.

The fuel tank in a diesel engine

There is air in the fuel system.

X Refuel the vehicle.

vehicle has been run completely

X Switch on the ignition for approximately 10 seconds (key in posi-

dry and the engine will not start.

tion 2 ( Y page 62) in the ignition lock).

X Start the engine continuously for up to 40 seconds until it runs

smoothly.

The fuel system is now free of air.

If the engine does not start:

X Wait two minutes.

X Repeat the starting procedure for up to 40 seconds.

If the engine still does not start:

X Consult a qualified specialist workshop.

232

Practical advice

Troubleshooting

Engine

Problem

Possible cause/consequence

Suggested solutions

X Turn the key back to position 0 ( Y page 62) in the ignition lock

The engine will not start. You can

R The engine electronics system

hear the starter motor operating.

is malfunctioning.

before the next starting attempt.

X Try to start the engine again ( Y page 87). When doing so, remember

R There is a malfunction in the

that excessively long and frequent attempts to start the engine will

fuel supply.

drain the battery.

R The on-board voltage is too low

If the engine does not start after several attempts:

because the starter battery is

X Consult a qualified specialist workshop.

too weak or discharged.

The engine will not start. You can The fuel tank has been run dry.

X Refuel the vehicle.

hear the starter motor operating.

X Bleed the fuel system ( Y page 232).

The reserve fuel warning lamp is

on and the fuel gauge shows 0.

The engine will not start. You can- The on-board voltage is too low X Jump-start the vehicle ( Y page 266).

not hear the starter motor oper- because the starter battery is too If the engine does not start despite attempting to jump-start it:

ating.

weak or discharged.

X Consult a qualified specialist workshop.

The starter motor was exposed to

X Allow the starter motor to cool down for approximately two

a thermal load that was too high.

minutes.

X Try to start the engine again.

If the engine still does not start:

X Consult a qualified specialist workshop.

233

Practical advice

Troubleshooting

Problem

Possible cause/consequence

Suggested solutions

Vehicles with a petrol engine:

There is a malfunction in the

X Only depress the accelerator pedal slightly.

engine electronics or a mechani-

The engine is not running

X Have the cause rectified immediately at a qualified specialist work-

cal component of the engine con-

smoothly and is misfiring.

shop.

trol unit.

Otherwise, non-combusted fuel may get into the catalytic converter

and damage it.

A coolant temperature of over

The coolant level is too low. The

X Stop as soon as possible and allow the engine and the coolant to

120 °C is displayed. The coolant

coolant is too hot and the engine

cool down.

warning lamp may also be on and

is no longer being cooled suffi-

X Check the coolant level ( Y page 175). Observe the warning notes

a warning tone may sound

ciently.

as you do so and top up the coolant if necessary.

( Y page 97).

If the coolant level is correct, the

X If the coolant temperature is less than 120 °C, you can continue

radiator fan may be faulty. The

driving to the nearest qualified specialist workshop.

coolant is too hot and the engine

X Avoid heavy loads on the engine as you do so, e.g. driving on

is no longer being cooled suffi-

mountain roads and stop/start driving.

ciently.

234

Practical advice

Troubleshooting

AUTOTRONIC*

Problem

Possible cause/consequence

Suggested solutions

The transmission has problems

The transmission is losing oil.

X Have the transmission checked at a qualified specialist workshop

shifting gear

immediately.

The acceleration ability is deteri- The transmission is in emergency

X Stop the vehicle.

orating.

mode.

X Move the selector lever to position P.

The one-touch gearshifting is no

X Turn the key to position 0 in the ignition lock.

longer working.

X Wait at least 10 seconds before restarting the engine.

The transmission no longer

X Move the selector lever to position D or R.

changes gear.

X Have the transmission checked at a qualified specialist workshop

immediately.

* optional

235

Practical advice

Troubleshooting

Parktronic*

Problem

Possible cause/consequence

Suggested solutions

Only the red segments in the

Parktronic has malfunctioned

X If problems persist, have Parktronic checked at a qualified spe-

Parktronic warning display are lit. and has switched itself off.

cialist workshop.

You also hear a warning tone for

approximately two seconds.

Parktronic is deactivated after

approximately 20 seconds and

the indicator lamp in the Park-

tronic button lights up.

Only the red segments in the

The Parktronic sensors are dirty

X Clean the Parktronic sensors ( Y page 196).

Parktronic warning display are lit. or there is interference.

X Switch the ignition back on.

Parktronic is deactivated after

approximately 20 seconds.

Only the red segments in the

The problem may be caused by an

X See if Parktronic functions in a different location.

Parktronic warning display are lit. external source of radio or ultra-

Parktronic is deactivated after

sound waves.

approximately 20 seconds.

* optional

236

Practical advice

Troubleshooting

Headlamps

Problem

Possible cause/consequence

Suggested solutions

The headlamps or the turn signals Air humidity is very high.

X Drive with the headlamps switched on.

in the exterior mirrors are misted

The headlamps are demisted after a short distance.

up on the inside.

The headlamp housing is not

X Have the headlamps checked at a qualified specialist workshop.

sealed and moisture has been

able to enter.

Windscreen wipers

Problem

Possible cause/consequence

Suggested solutions

The windscreen wipers are jam-

Leaves or snow, for example, may

X For safety reasons, you should remove the key from the ignition

med.

be obstructing the windscreen

lock.

wiper movement. The wiper

X Remove the cause of the obstruction.

motor has been deactivated.

X Switch the windscreen wipers back on.

The windscreen wipers fail com-

G Risk of accident

X Select another wiper speed on the combination switch.

pletely.

X Have the windscreen wipers checked at a qualified specialist work-

The windscreen wiper drive is

shop.

malfunctioning.

237

Practical advice

Troubleshooting

Side windows

Problem

Possible cause/consequence

Suggested solutions

A side window will not close.

Objects are trapped between the

X Remove the objects.

window and the door frame.

X Close the side window.

There are objects in the window

X Remove the objects.

guide rail which are preventing

X Close the side window.

the window from closing.

You cannot see the cause.

X Close the side window with increased force or without the anti-

entrapment feature ( Y page 85).

Mirrors

Problem

Possible cause/consequence

Suggested solutions

An exterior mirror has been

Vehicles with exterior mirrors that cannot be folded in/out electri-

pushed out of position.

cally:

X Move the exterior mirror into the correct position manually.

Vehicles with electrically folding exterior mirrors*:

X Press the mirror-folding button* ( Y page 71) repeatedly until you

hear a distinct click.

The mirror housing is engaged again and you can adjust the mirror

as usual ( Y page 71).

* optional

238

Practical advice

Troubleshooting

Key

Problem

Possible cause/consequence

Suggested solutions

You cannot lock or unlock the

The key batteries are discharged

X Point the tip of the key at the driver's door handle from close range

vehicle using the key.

or nearly discharged.

and try to unlock or lock the vehicle again.

If this does not work:

X Unlock the vehicle using the emergency key element

( Y page 241).

X Check the key batteries ( Y page 244) and replace them if neces-

sary ( Y page 244).

The key is faulty.

X Unlock the vehicle using the emergency key element

( Y page 241).

X Have the key checked at a qualified specialist workshop.

The battery charge indicator lamp The key batteries are discharged.

X Change the batteries ( Y page 244).

of the key does not go on during

the test.

You have lost a key.

X Have the key cancelled at a Mercedes-Benz Service Centre.

X Report the loss immediately to the vehicle insurers.

X If necessary, have the manual locks changed too.

You have lost the emergency key

X Report the loss immediately to the vehicle insurers.

element.

X If necessary, have the manual locks changed too.

The engine cannot be started

The steering lock is mechanically

X Remove the key and reinsert it into the ignition lock. While doing

using the key.

blocked.

this, turn the steering wheel in both directions.

239

Practical advice

Troubleshooting

Trailer towing

Problem

Possible cause/consequence

Suggested solutions

The ball coupling cannot be

G Risk of accident

X Remove the ball coupling and clean it ( Y page 196). If the ball cou-

locked.

pling still cannot be locked, remove the ball coupling. It must no

The ball coupling is dirty.

longer be used to tow a trailer, as safe operation is not guaranteed.

The key cannot be removed from

The trailer tow hitch is damaged.

the ball coupling.

X Have the entire trailer tow hitch checked at a qualified specialist

workshop.

Parking up the vehicle

Problem

Possible cause/consequence

Suggested solutions

The vehicle is to be left parked up Damage resulting from non-use

X Visit a qualified specialist workshop and seek advice.

for longer than six weeks.

may occur if the vehicle is parked

X Disconnect the battery ( Y page 265).

up for long periods.

240

Practical advice -> Troubleshooting for Your Mercedes A Class 4 Door Second Generation (2004-2011)

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