Hyundai Sonata LF: Engine Control System / Knock Sensor (KS) Description and Operation
Knocking is a phenomenon characterized by undesirable
vibration and noise and can cause engine damage. Knock Sensor (KS) is
installed on the cylinder block and senses engine knocking.
When knocking occurs, the vibration from the cylinder block
is applied as pressure to the piezoelectric element. When a knock
occurs, the sensor produces voltage signal. The ECM retards the ignition
timing when knocking occurs. If the knocking disappears after retarding
the ignition timing, the ECM will advance the ignition timing. This
sequential control can improve engine power, torque and fuel economy.

Inspection
1.
Check the signal waveform of the CMPS and CKPS using the GDS.
Specification: Refer to “Wave Form”
Removal
•
DON’T remove the camshaft position sensor while the engine
is running or right after engine is turned off...
Other information:
C..
Service Point Target Auto Calibration (SPTAC)
This procedure provides a way to calibrate the camera by
having the service technician align the car to a well lit simulated
straight road target; preferably wall mounted.
The LDWS camera will have a "System Out of Calibration" DTC set if not operating within specified tolerances...