Automatic Ventilation (if equipped)
When the ignition switch is in the ON position or when the engine is running and temperature is below 59°F (15°C) with the recirculated air position selected more than five minutes, the air intake position will automatically change to the outside (fresh) air position.
To cancel or reset the Automatic Ventilation
When the air conditioning system is on, select Face Level mode and while pressing the A/C button, press the recirculated air position button five times within three seconds.
Sunroof Inside Air Recirculation (if equipped)
When the heater or air conditioning system is on with the sunroof opened, the outside (fresh) air position will be automatically selected. At this time, if you press the recirculated air position button, the recirculated air position will be selected but will change back to the outside (fresh) air position after 3 minutes.
When the sunroof is closed, the air intake position will return to the original position that was selected.
Hyundai Elantra AD (2016-2020) Service Manual: Knock Sensor (KS) Repair procedures
Removal
1.
Turn the ignition switch OFF and disconnect the battery negative (-) cable.
2.
Disconnect the knock sensor connector (A).
3.
Remove the intake manifold.
(Refer to Engine Mechanical System - "Intake Manifold")
4.
Remove the installation bolt (A), and then remove the sens ...
Hyundai Elantra AD (2016-2020) Service Manual: Components and Components Location
Component Location
1. Horn switch2. Horn relay (Built - in PCB Block)3. Horn (Low pitch)4. Horn (High pitch)5. Clock spring
...