Published in the February 2018 issue of “Die Porsche Kassette”
Ⓒ2018 Technolab / PedrosGarage.com
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If you drive a newer Porsche (from the 90s and forward) it is SENSORED!
The newer the Porsche, the more SENSORED it is.
This whole article is completely SENSORED!
Obviously, I’m referring to the myriad of sensors that keep your Porsche running.
You think I’m exaggerating when I say myriad?
Let’s try to enumerate some of them and explain their use and importance.
But first, What is a Sensor?
A sensor is a device that detects or measures a some type of input from the physical environment and records, indicates, or otherwise responds to it. This specific input could be light, heat, moisture, pressure, or any one of a great number of other environmental phenomena.
Coolant Temperature Sensor
It keeps tabs on coolant temperature so the car doesn’t overheat.
It will interact with a light on the dash if the coolant temp goes too high and alert you of the situation. Always check this gauge while driving.
Ambient Temperature Sensor
Installed in the front bumper it measures ambient temperature in order to determine how much cooling or heating is necessary for cabin comfort.
Cabin Temperature Sensor
Hidden inside the dash, it monitors the cabin’s temperature, sending the data to the HVAC system. There may be more than one of these sensors if you have individual temperature controls.
Engine Bay Temperature Sensor
Installed inside the engine bay, it determines the need for the electric blower to activate to keep the engine bay from overheating.
Engine Air Intake Temperature Sensor
Installed in the airbox it keeps tabs of incoming air temperature. The data is used by the engine management computer DME or ECU to obtain the perfect air-to-gas ratio.
Oil Temperature Sensor
Installed in the oil pump housing it monitors the engine’s oil temperature and will trigger a warning signal if too low.
Transmission Fluid Temperature Sensor
Installed in the Tiptronic and/or PDK it monitors the transmission fluid’s temperature to keep it operating optimally.
A/C Temperature Sensor
Monitors the cooling/heating of the air in the blower box of the HVAC system.
A/C Airflow Sensor
Monitors the amount of air flow being produced by the blower.
Monitors any movement inside the cabin and sends a signal to the alarm unit.
Crankshaft Position Sensor
Installed next to the bell housing it “reads” the crankshaft’s position. It’s also called the Top Dead Center (TDC) sensor.
Camshaft Position Sensor
One in each engine bank, they monitor the movement of the cams for valve-timing purposes. This is especially important for cars equipped with variable timing such as Variocam and Variocam Plus.
Installed before and after the primary catalytic converters they monitor the amount of oxygen present in the exhaust before and after going through the cats. The DME then determines how well the fuel mixture was “consumed”. Normally there are 4 per vehicle. These are the most unnecessarily replaced sensors.
Coolant Level Sensor
Obviously, this one monitors the level of coolant. It’s located on the coolant reservoir, towards the bottom. A light on the dash will alert you if level is low. If it is low, find out why and don’t just top it off.
Gasoline Level Sensor
This sensor tells you how much fuel is in the tank. The sensor itself is immersed in gasoline, inside the tank, right next to the fuel pump. It interacts with the gauge cluster to visually give you the information.
Windshield Washer Level Sensor
Very similar to the coolant level sensor, this one tells you when you are almost out of windshield washer fluid. Top off as soon as the low level message appears.
Oil Level Sensor
Keeps tabs on how much oil is in the engine and will set off an alarm if not enough oil is present. Many times a second sensor is enclosed in the same housing...
... the Oil Temperature Sensor which makes sure that the oil (and therfore the engine) doesn't overheat.
Tire Pressure Monitoring System sensors are located one in each wheel. They are battery-powered pressure sensors that communicate with the car’s electronics and monitor each tire’s individual pressure and many times the tire’s temperature as well. These sensors, because they are battery powered, should be replaced every time tires are changed to ensure that they work properly through the life of the tires. These are the ones that let you know if you have a puncture, or are loosing air pressure in a tire.
Give you an audible “beep-beep-beep” as your car’s bumper (front or rear) approaches an obstacle or another car. These are visible as “buttons” on each bumper. There are 4 or 5 per bumper. This type of sensor is called a proximity sensor.
Mass Airflow Sensor
Also known as the MAF, this important sensor measures the amount of air that goes into the intake tube. It then sends the information to the DME, which in turn calculates how much gasoline the injectors need to spray in order for the mixture to be 14.7:1 or at the stoichiometric point. Most often, when you get the Check Engine Light (CEL) the MAF has something to do with it.
Brake Wear Sensor
There is one sensor generally on every brake pad, so a total of 8 are usually present. As the brake pads wear, they get thinner and thinner. Eventually the sensor, which is inserted in a small hole in the brake pad is exposed and shorts out with the brake rotor, setting off the “Brake wear light” in the dash. Generally when the brake wear light comes on, the sensor must be replaced.
Oil Pressure Sensor
Located on one of the valve covers it either shows actual oil pressure (Carrera) or just a light on the dash (Boxster & Cayman) when the pressure is too low. These generally measure pounds per square inch (psi) or BAR (1 BAR = 1 atmosphere = 14.5 psi).
Fuel Pressure Sensor
Installed in the fuel injection rail it monitors the fuel pressure present at the injectors. It interacts with the fuel pressure regulator to maintain optimal pressure.
A/C Pressure Sensor
Keeps tabs of the pressure inside the A/C system to protect the compressor in case of an anomaly.
A/C Evaporator Anti-Ice Sensor
This sensor protects the air conditioner’s evaporator from freezing by sensing ice build-up on the evaporator’s fins.
Immobilizer RFID Sensor
This sensor, in the form of a mini
pill or “grain of rice”, is embedded
inside the ignition key’s fob.
It sends an encoded signal to the
car’s Central Locking Unit (CLU)
that will only allow the car’s engine
to crank (start) if it matches the
same signal in it’s memory.
One of the best anti-theft devices. (RFID = Radio Frequency Identification)
Engine Knock Sensor
Looks for telltale engine vibrations caused by knocking. If present, the DME retards timing. We have seen some times when people have replaced the engine or transmission mounts for the “performance” or “racing” type, that the car loses power. If this happens it could be the knock sensors miss-reading the engine vibrations.
Also known as a Rotational Speed Sensor. It is a gyroscopic device that measures a Porsche’s angular velocity around its vertical axis. The angle between the car’s heading and the car’s actual movement direction is called the slip angle, which is related to the yaw-rate. This sensor is part of the Porsche Stability Management (PSM) system. If too much yaw rate is detected, the PSM will slow down one or more wheels to correct the problem.
There are multiple speed sensors within a Porsche. Some monitor the speed of the wheels, the transmission, the flywheel, etc. The signal is sent to the corresponding control unit such as the Gauges (speedometer), Cruise Control, ABS control unit, DME, etc.
Steering Angle Sensor
As its name implies, it monitors the angle of the steering wheel but not just for alignment of the wheel but also sends a signal to the PSM unit letting it know how much steering input the driver is having to use for a particular maneuver. The PSM then determines whether it should intervene or not.
Depending on the car and model year the can be from 1 to over 12 airbag sensors in a Porsche. These sensors when actuated in a collision, immediately send a signal to the corresponding airbag(s) to deploy and therefore protect the occupant.
Passenger Occupancy Sensor is a weight-sensitive element that notices if there is more than a certain amount of weight in a passenger’s seat. This is used for people who put their babies in the front seat don’t have the airbag deploy into the back of the infant’s head in a collision, but a heavier passenger will get the airbag protection if required.
There are several sensors in the ABS System. Their main function is to determine when a wheel is about to skid due to braking or road conditions and not allow the particular wheel to lock up therefore keeping the car tracking in a controllable manner.
Accelerator Pedal Sensor
Senses the position of the accelerator pedal for cars with electronic (drive-by-wire) throttle bodies. The signal from this sensor tells the DME how much gas the driver is requesting and therefore counteracts with the correct amount of air by opening or closing the throttle body to match that request.
Throttle Position Sensor
In cars that have a cable-operated throttle body, this sensor monitors the position of the throttle body’s butterfly valve. The signal is sent to the DME for air mixture purposes.
Monitors for rain droplets on the windshield and can automatically trigger the wipers for you.
Interior Monitoring Sensor
This is a motion detector which monitors the cabin and triggers the alarm if it senses movement while the alarm is on.
Headlight Leveling Sensor
Automatically levels the headlight beams adjusting and compensating for added weight due to passengers and/or heavy items in the trunk(s).
And these are just the usual ones. Newer cars have even more sensors such as:
Intelligent Cruise Control Sensor
This sensor basically sends a radar signal forward so it can monitor the distance of the vehicle in front. It can then maintain a safe distance and is able to accelerate, decelerate and brake in order to maintain that safe distance.
Lane Change Sensor
Monitors the sides of the vehicle and advises the driver by either an audible tone, a stiffening of the steering wheel or both as to the departure of a lane when the corresponding turn signal is not in use. This is a safety sensor in case the driver gets distracted or falls asleep and the vehicle starts to leave its lane.
Blind Spot Sensor
Monitors your Porsche’s rearview blind spots. When a vehicle is in one of your blind spots it alerts you with a visual warning light on the corresponding rearview mirror and/or with an audible “beep”.
Automatic High Beam Sensor
When set to “on”, the sensor monitors incoming traffic and dims the high beam so as to not blind incoming traffic. Once traffic is past it can then automatically set the high beams for safer driving at night. This is effective for highway use.
You can expect exponentially more sensors once cars have the capability of driving themselves.