2005 PORSCHE CAYENNE TURBO overheating

Controls, Safety, Instruments
65
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
141
Parking heater faultsIn the event of faults in the parking heater, no
function symbol appears on the display – only the
remaining running time is shown. The display
flashes on briefly and then goes completely dark.
fHave the parking heater checked at an
authorized Porsche dealer.
In the event of a serious accident, the parking
heater switches off automatically for safety
reasons.
The parking heater is not ready for operation.
fPlease consult an authorized Porsche dealer.
If the temperature rises, the overheating protec-
tion switches the parking heater off automatically.
The parking heater is not ready for operation.
fPlease consult an authorized Porsche dealer.
The parking heater is switched off automatically if
the voltage is too low. The parking heater is
temporarily unavailable.

Maintenance, Car Care
255
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.

298
Practical Tips, Minor Repairs
B- Screw coupling for compressor connection
C- Pressure tester
D- Hand valve for tire filling
E- Air bleed screw
F- Filler connection for tire valve7. Screw screw coupling B into the compressor
connection (in footwell of the front passenger
seat).
8. Screw filler connection F onto the tire valve.
Warning!
D a n g e r o f i n j u r y a n d r i s k o f d a m a g e i f t h e o p -
erating unit is used improperly.
fUse this operating unit only to inflate or to bleed air from the tires of this vehicle.
9. Switch ignition on.
10.Press hand valve Duntil the correct tire pres-
sure is achieved.
Monitor the tire pressure with pressure tester
C during the inflation process.
11.Unscrew the screw coupling from the com-
pressor connection.
12.Unscrew filler connection from the tire valve.
13.Stow tire filler hose in the bag.
14.Close bag with Velcro strip.
15.Lower the seat cushion, push it under the
backrest and press it down at the front.
Make sure that the buckles are accessible.Note on operation
The compressor features a protective function
against overheating and switches itself off auto-
matically if necessary. The compressor must cool
down for a few minutes after automatic deactiva-
tion.
Reducing tire pressure on vehicles with
air suspensionfOpen air bleed screw E until the correct tire
pressure is achieved.
Monitor the tire pressure with pressure tester
C while correcting the tire pressure.