Gas cooktop shows E21 or a fault indicator; one or more burners will not ignite even though others work.

Safety first: Turn off gas and disconnect power before handling burner components.

• Check burner assembly: Remove the burner cap and head. Clean any food debris or grease from the electrode area and burner ports.
• Inspect electrode: Look for cracks in the ceramic insulator or a broken tip. Replace the electrode if damaged.
• Verify cap alignment: Refit the burner head and cap correctly; misalignment can prevent proper gas flow and ignition.
• Check wiring: From underneath, ensure the electrode wire is firmly connected to both the electrode and the ignition transformer.
• Test ignition switch: If the electrode and wiring are good but there is no clicking when that knob is turned, the ignition switch on the gas valve may be faulty and should be replaced.