Water heater does not ignite, burner never lights, display shows E01 shortly after a hot water demand.

Safety first: Turn off electrical power to the water heater and close the gas isolation valve before removing any covers. Wait for the unit to cool down.

• Check gas supply: Ensure the main gas cock to the Chaffoteaux water heater is fully open and that other gas appliances in the home work correctly. If there is no gas supply, contact your gas provider.
• Inspect the burner area: Remove the front casing according to the user/installation manual. Visually inspect the main burner and injectors for dust, rust flakes, or spider webs. Gently clean with a soft brush and vacuum. Do not enlarge injector orifices.
• Check ignition electrode: Locate the ignition electrode near the burner on the combustion chamber. Inspect the ceramic for cracks and the tip for heavy carbon deposits. Clean the tip with fine emery cloth. Ensure the electrode gap and position match the service manual. Tighten the mounting screw and check the ignition cable for damage or loose connections on the ignition transformer/PCB.
• Check flame detection electrode: On many Chaffoteaux models the flame sensor is combined with or next to the ignition electrode. Clean it as above and ensure the cable is firmly connected to the control board. A dirty or misaligned sensor will cause E01 even if the burner lights briefly.
• Reset and test: Restore gas and power, then reset the appliance using the front panel reset button. Open a hot water tap fully and observe ignition. If E01 persists after cleaning and confirming gas supply, the gas valve coil or control PCB may be faulty and should be tested/replaced by a qualified technician.

Do not attempt to adjust gas valve settings or combustion parameters without proper instruments and certification.