2005 PORSCHE CAYENNE S engine overheat

Controls, Safety, Instruments
67
Brake pedal
Warning!
Risk of an accident.
Any obstruction of the brake pedal could in-
crease the stopping distance.
fAlways check the movement of the brake pedal
before driving and make sure that it is not ob-
structed by a floor mat or any other object.
fSecure the floor mat to prevent it from sliding
into positions that could interfere with the safe
operation of your vehicle.
Your Porsche dealer will be glad to offer you
floor mats of the correct size including a secur-ing possibility.
Note
In case one of the two brake circuits fails, in-
creased pedal travel is required to bring your vehi-
cle to a full stop.
Warning!
To avoid overheating and premature wear of
the brakes:
fBefore descending a steep grade, reduce
speed and shift the transmission into a lower
driving position to control speed.
fDo not “ride the brakes“ by resting your foot on
the pedal when not intending to apply brake
pressure.
fDo not hold the pedal down too long or too of-
ten. This could cause the brakes to get hot and not function properly.
Brake boosterThe brake booster assists braking only when
the engine is running.
When the car is moving while the engine is not run-
ning, or if the brake booster is defective, more
pressure on the brake pedal is required to bring
the car to a stop.
Moisture, road salt or grit on brakes affects brak-
ing. When the vehicle is driven on salted or gritted
roads for extended periods, the brakes should be
washed down thoroughly about every 2 weeks. An
automatic carwash facility cannot do this job prop-
erly. Brakes will dry after a few cautious brake ap-
plications.
Warning!
Driving through water may reduce the trac-
tion. Moisture on brakes from road water, car
wash, or a coating of road salt or grit may af-
fect braking efficiency.
fCautiously apply brakes to test brakes after being exposed.

Controls, Safety, Instruments
69
Warning!
fDo not obstruct the pedal travel with floor mats
or other objects.
The brake booster is ready for operation only
while the engine is running.
If the engine is switched off or there is a defect in
the brake booster, much greater force has to be
applied to the pedal when braking.
fPlease observe the chapter “TOWING” on
Page 350.
In heavy rain, while driving through water or after
leaving a car wash, the braking action may be de-
layed and increased pressure may be required.
fFor this reason, keep further back from the ve-
hicle in front and “dry” the brakes by applying
them at intervals. Make sure that following traf-
fic is not affected.
After a long drive over salted or gritted roads, a
coating may form on the brake discs and pads
that significantly reduces friction and thus braking
action.
fTherefore, clean the brake discs and pads ap-
prox. every 2 weeks with a strong jet of water.
The cleaning effect of automatic car washes is
insufficient.
To prevent corrosion of the brake discs, “brake
them dry” before parking the car.fEven though the brake discs consist of alloyed
grey cast iron, they will unavoidably start to
corrode if your car is parked for an extended
period. The brakes will tend to “rub” as a re-
sult.
The nature, extent and effects of corrosion de-
pend on the amount of time the vehicle was
parked, whether road salt or grit was spread
and whether grease-dissolving agents were
used in car washes.
If the braking comfort is noticeably impaired,
we recommend having the brake system
checked by experts at an authorized Porsche
dealer.
fTo relieve the braking system on downhill
stretches, change down to a lower gear in
good time to obtain engine braking.
If engine braking is insufficient on steep
stretches, operate the footbrake at intervals.
Continuous braking overheats the brakes and
reduces the braking effect.
fPlease observe the chapter “BRAKE-FLUID LE-
VEL” on Page 251.

Controls, Safety, Instruments
79
Emission ControlThe emission control system detects malfunctions
early that could, for example, cause increased pol-
lutant emissions or consequential damage.
Faults are indicated by the warning light in the in-
strument panel by being continuously lit or flash-
ing.
The faults are recorded in the control unit's fault
memory.
The warning light in the instrument panel lights up
when the ignition is switched on as a lamp check
and goes out approx. 4 seconds after the engine
starts.The warning light in the instrument panel flashes to
indicate operating states (e.g. engine misfiring)
which might cause damage to certain parts of the
emission control system.
fIn this case, immediately reduce the engine
load by easing off the accelerator.
The warning light in the instrument panel is lit
continuously after the critical range is left.
fIn order to avoid consequential damage to the
engine or emission control system (e.g. cata-
lytic converter) go immediately to the nearest
authorized Porsche dealer to have the fault
diagnosed and rectified.
Caution!
Risk of damage. If the warning light in the in-
strument panel continues flashing even when
you have eased off the accelerator pedal,
the emission control system may overheat.
fStop as soon as possible in a safe place.
Make sure that combustible materials, such as
dry grass or leaves, cannot come into contact
with the hot exhaust system.
fSwitch off the engine.
fContact your nearest authorized Porsche deal-er to have the fault rectified.
Check engine warning light

Maintenance, Car Care
263
Emission Control SystemIn the interest of clean airPollution of our environment has become a prob-
lem that is of increasing concern to all of us. We
urge you to join us in our efforts for cleaner air in
controlling the pollutants emitted from the auto-
mobile.
Porsche has developed an emission control sys-
tem that controls or reduces those parts of the
emission that can be harmful to our environment.
Your Porsche is equipped with such a system.
Porsche warrants the Emission Control System in
your new car under the terms and conditions set
forth in the Warranty Booklet.
You, as the owner of the vehicle, have the respon-
sibility to provide regular maintenance service for
the vehicle and to keep a record of all mainte-
nance work performed. To facilitate record keep-
ing, have the service performed by authorized
Porsche dealers. They have Porsche trained tech-
nicians and special tools to provide fast and effi-
cient service.To assure efficient operation of the Emission
Control System:
fHave your vehicle maintained properly and in
accordance with the recommendations de-
scribed in your Maintenance Booklet. Lack of
proper maintenance, as well as improper use
of the vehicle, will impair the function of the
emission control system and could lead to
damage.
fDo not alter or remove any component of the
emission control system.
fDo not alter or remove any device, such as
heat shields, switches, ignition wires, valves,
etc., which are designed to protect your vehi-
cle's emission control system. In addition to
serious engine damage, this can result in a fire
if excess raw fuel reaches the exhaust system.
fDo not continue to operate your vehicle if you
detect engine misfire or other unusual operat-
ing conditions.
Parking
Warning!
Danger of fire.
fDo not park or operate the vehicle in areas
where the hot exhaust system may come in
contact with dry grass, brush, fuel spill or oth-
er flammable material.
fIf your car catches on fire for any reason, call
the fire department. Do not endanger your life by attempting to put out the fire.
Undercoating
Danger!
Danger of fire and serious personal injuries
or death.
fDo not apply additional undercoating or rust-
proofing on or near the exhaust manifold, ex-
haust pipes, catalytic converters or heat
shields. During driving the substance used for undercoating could overheat and ignite.

264
Maintenance, Car Care
How Emission Control WorksWhen an automobile engine is running, it uses en-
ergy generated through the combustion of a mix-
ture of air and fuel. Depending on whether a car is
driven fast or slowly or whether the engine is cold
or hot, some of the fuel (hydrocarbons) may not
be burned completely, but may be discharged into
the engine crankcase or exhaust system. Additon-
al hydrocarbons may enter the atmosphere
through evaporation of fuel from the fuel tank.
These hydrocarbons (HC), when released into the
air, contribute to undesirable pollution.
In addition, carbon monoxide (CO) and oxides of
nitrogen (NOx) contribute to engine emissions.
They, too, are formed during the combustion pro-
cess and discharged into the exhaust system.
To reduce these pollutants, your Porsche is
equipped with a precisely calibrated fuel injection
system to assure a finely balanced air/fuel mixture
under all operating conditions.
Oxygen sensorThe oxygen sensor, installed in the exhaust pipe
continuously senses the oxygen content of the ex-
haust and signals the information to an electronic
control unit. The control unit corrects the air/fuel
ratio, so the engine always receives an accurately
metered air/fuel mixture.Crankcase ventilationThrough crankcase ventilation, undesirable emis-
sions from the engine crankcase are not permit-
ted to reach the outside atmosphere. These emis-
sions are recirculated from the crankcase to the
air intake system. From here the emissions mix
with the intake air and are later burned in the en-
gine.Catalytic convertersThe catalytic converters are efficient “clean-up“
devices built into the exhaust system of the vehi-
cle. The catalytic converters burn the undesirable
pollutants in the exhaust gas before it is released
into the atmosphere.
The exclusive use of unleaded fuel is critical-
ly important for the life of the catalytic con-
verters. Therefore, only unleaded fuel must
be used.The catalytic converters will be damaged by:
– push or tow starting the vehicle
– misfiring of the engine
– turning off the ignition while the vehicle is mov-
ing or
– driving until the fuel tank is completely empty
– by other unusual operating conditions.
fDo not continue to operate your vehicle under
these conditions, since raw fuel might reach
the catalytic converters. This could result in
overheating of the converters. Federal law pro-
hibits use of leaded fuel in this car.

270
Maintenance, Car Care
UndercoatingThe underside of your car is durably protected
against chemical and mechanical influences.
As it is not possible to exclude the risk of damage
to this protective coating in day to day driving, it
is advisable to have the underside of the car in-
spected at certain intervals - preferably before the
start of winter and again in spring - and the under-
coating restored as necessary.
Your authorized Porsche dealer is familiar with the
bodyseal treatment procedures and has the nec-
essary equipment for applying factory approved
materials. We recommend that you entrust them
with such work and inspections.
Unlike conventional spray oils, undercoating and
rust-proofing compounds based on bitumen or
wax do not attack the sound-proofing materials ap-
plied at the factory.
Danger!
Danger of fire and serious personal injuries.
fDo not apply additional undercoating or rust-
proofing on or near the exhaust manifold, ex-
haust pipes, catalytic converters or heat
shields. During driving the substance used for undercoating could overheat and ignite.
fBefore applying fresh underseal, carefully re-
move deposits or dirt and grease. Once it has
dried, the new undercoating compound forms
a tough protective coating which provides effi-
cient rust-proofing of the floor panels and com-
ponents.
fAlways apply a fresh coating of suitable preser-
vative to unprotected areas after cleaning the
underside of the body, the transmission, the
engine or carrying out repairs to under-body,
engine or transmission components.
Effective rust-proofing is particularly important
during the cold weather season. If your car is driv-
en frequently in areas where salt has been spread
on the roads, the whole engine compartment
should be cleaned thoroughly after the winter to
prevent salt from causing any lasting damage. A
full under-body wash should also be performed at
the same time.