Furnace fails to ignite, burner does not light, ignition sequence aborts after a few attempts

Safety first: Turn off electrical power to the furnace at the isolator switch and close the gas isolation valve before removing any covers. Allow the appliance to cool fully.

Steps to check:

• Reset the boiler/furnace: Restore power and follow the Baxi user manual to perform a reset. If E01 returns repeatedly, continue with checks.
• Inspect ignition electrode: Isolate power and gas again. Remove the combustion chamber cover. Check the ignition electrode on the burner assembly for cracks, heavy carbon deposits, or damaged insulation. Clean gently with fine emery cloth and ensure the spark gap is as specified in the Baxi service manual.
• Check flame sensor (ionisation probe): Clean any oxidation or soot. Ensure the probe is correctly positioned in the burner flame path and the lead is firmly connected to the PCB.
• Verify gas supply: Confirm that the external gas cock is open and that other gas appliances in the property work correctly. If gas supply is suspect, contact the gas supplier.
• Check gas valve operation: With a qualified gas-safe technician only: measure voltage at the Baxi gas valve coil during ignition demand and verify correct inlet and burner pressure using a manometer.

When to call a professional: Any work involving gas pressure adjustment, gas valve replacement, or combustion analysis must be carried out by a certified gas technician familiar with Baxi appliances.