1. Disconnect the negative battery cable..
2. Remove the front bumper..
3. Remove the horn..
4. Apply battery positive voltage to horn terminal A, and connect the horn retaining bolt to ground as shown in the figure, and then verify that the horn sounds.

If the horn does not sound, replace the horn.
Horn
Horn Removal/InstallationCargo Compartment Light Inspection
1. Disconnect the negative battery cable..
2. Remove the cargo compartment light..
3. Verify that the continuity between the cargo compartment light terminals is
as indicated in the table.
If not as indicated in the table, replace the cargo compartment light..
...
Air Fuel Ratio (A/F) Sensor Heater Control [Skyactiv G 2.0]
Outline
Based on the control of the A/F sensor heater, a stabilized oxygen concentration
is detected even at low exhaust temperatures, and feedback control of fuel injection
even at cold engine start is made possible for improved cold temperature exhaust
emission performance.
...
Car Navigation System Does Not Start Operation [Car Navigation System]
Possible DTC
Even if the NAVI mode is selected, the car-navigation system screen does
not display.
POSSIBLE CAUSE
NAV switch malfunction
Power supply fuse (+B, ACC) burnt out
Open or short circui ...