Heater attempts to ignite but shuts down with F2 error on the display.

Safety first: Turn off gas at the appliance isolation valve and isolate electrical power. Gas work should only be carried out by a suitably qualified gas engineer.

• Check gas supply: Confirm that the gas isolation valve to the Certikin heater is fully open and that other gas appliances in the property are operating normally.
• Inspect flue and air intake: Ensure the flue terminal and combustion air openings are not blocked by leaves, debris, or nesting material.
• Visual burner check: With power off and gas isolated, remove the front panel and inspect the burner tray for rust, soot, or debris. Do not dismantle gas components unless qualified.
• Check ignition electrode: Look for cracked porcelain, damaged tip, or loose ignition lead on the Certikin ignition electrode. Reseat the lead firmly on both the electrode and ignition module.
• Reset heater: Restore power and gas, then attempt to restart. If F2 reappears after several attempts, stop trying to ignite.

Persistent F2 faults usually require professional testing of gas pressure, burner injectors, ignition electrode gap, and flame rectification circuit.