This warning light illuminates:
If there is a malfunction with the AFLS:
1. Drive carefully to a safe location and stop the vehicle.
2. Turn the engine off and restart the engine. If the indicator light remains on, have your vehicle inspected by an authorized HYUNDAI dealer.
Hyundai Sonata LF 2014-2019 Service Manual: Heated Oxygen Sensor (HO2S) Repair procedures
Inspection
1.
Turn the ignition switch OFF.
2.
Disconnect the HO2S connector.
3.
Measure resistance between the HO2S terminals 2 and 5 [B1/S1].
4.
Measure resistance between the HO2S terminals 3 and 4 [B1/S2].
5.
Check that the resistance is within the specification.
Specifica ...
Hyundai Sonata LF 2014-2019 Service Manual: Catalytic Converter Repair procedures
Removal
1.
Remove the exhaust manifold.
(Refer to Engine Mechanical System - "Exhaust Manifold")
Installation
1.
Install in the reverse order of removal. ...