If your two-plate gas stove is catching flame behind the knob on one side, it indicates a potential issue with that particular burner. There could be a few reasons for this problem:
Gas leakage: There might be a gas leakage near the burner, which can cause flames to ignite behind the knob. Gas leaks are dangerous and should be addressed immediately. If you suspect a gas leak, turn off the gas supply to the stove, ventilate the area, and contact a professional gas technician to inspect and repair the stove.
Blocked or clogged burner: The burner on that side may be blocked or clogged, preventing proper gas flow and causing flames to escape from unintended areas. Cleaning the burner or removing any obstructions may resolve the issue. Make sure the burner is completely cooled down before attempting any cleaning.
Faulty gas valve or regulator: A malfunctioning gas valve or regulator can cause gas to escape from places other than the burner ports, leading to flames behind the knob. A professional technician should inspect and repair or replace any faulty components.
It is important to prioritize safety when dealing with gas appliances. If you notice flames behind the knob or suspect a gas leak, it is recommended to turn off the gas supply to the stove, avoid using the affected burner, and seek professional assistance to diagnose and fix the problem.