Keyless Access  

Keyless Access or Kessy (Keyless Entry Start and Exit System) is Volkswagen's automatic locking and starting system. It offers the driver maximum comfort, as they need to have their key with them, but don't need to take it out.

The key components of keyless vehicle access are the ID provider in the vehicle key, the electronic ignition lock, the start button, the control unit, the electric steering column lock and aerials and sensors in the door handles.

The key is identified using proximity sensors in the doorhandles and a pulse generator in the key housing, as soon as the driver is in within a range of around 1.50 metres from the vehicle. When the door handle (or boot lid) is operated, the vehicle is unlocked automatically. The activation of the steering and ignition required before beginning the journey can also be done electronically without keys in the ignition lock. If the driver has the key in the vehicle with them, the engine can be started using the start button. However, the vehicle key can also be used to operate the central locking like a normal key. When leaving the vehicle, all the driver needs to do is press the small locking button on the door handles to lock the vehicle.

See also:
Central locking
Easy Open

Image of Keyless Access on the centre console in the VW Golf

Knock sensor 

The knock sensor is attached to the engine on the outside and prevents harmful autoignition. The knocking effect is created by uncontrolled out-of-cycle combustion, producing extreme temperatures in the cylinder. These high levels of heat have a strong impact on engine components such as pistons, valves and the cylinder head and can lead to damage.
The knock sensor records the engine's structure-borne sound. The engine control unit compares the measuring pulses with the saved specifications and intervenes accordingly in the control of the engine, injection and ignition before combustion reaches the knock limit.
The knock sensor also detects the fuel quality. The higher the octane number, the more knock-resistant the fuel. This means that Super Plus, with an octane number of 98, ignites at a higher temperature than normal petrol, with an octane number of 95. However, if only lower fuel quality is available, the engine control unit automatically corrects the ignition time based on the information from the knock sensor. This avoids damage to the engine.