Sime gas water heater does not ignite; display shows E01 shortly after a hot water tap is opened.

Safety first: Turn the appliance OFF, close the gas isolation valve, and disconnect power before removing covers. If you ever smell gas continuously, ventilate the area and contact a qualified gas technician immediately.

Steps to check:

• Reset the heater: Use the reset button or power cycle the unit for 30 seconds. Try again with a hot water tap fully open.
• Check gas supply: Ensure the gas isolation valve to the Sime heater is fully open. Confirm other gas appliances in the home work normally.
• Inspect burner area: Remove the front panel. Check the main burner and injector rail for dust, rust flakes, or spider webs. Gently vacuum and clean with a soft brush (do not enlarge injector holes).
• Check ignition electrode: Locate the ignition electrode near the burner. Inspect for cracks in the ceramic, loose connection on the ignition cable, or heavy soot. Clean the tip with fine emery cloth and reseat the cable firmly.
• Check flame sensor (ionization electrode): Clean the rod with fine abrasive pad to remove oxidation. Ensure it is correctly positioned in the burner flame path.
• Gas valve operation (visual check only): With the cover back on and gas restored, run hot water and listen for the gas valve click and ignition spark. If there is spark but no flame and gas supply is confirmed, the gas valve may be faulty and must be tested/replaced by a certified technician.

When to call a professional: If E01 persists after cleaning electrodes and confirming gas supply, or if you suspect a faulty gas valve or control board, contact an authorized Sime service center. Do not attempt to adjust internal gas pressures yourself.