E07 error, fan may run but ignition does not occur; sometimes accompanied by flue-related warnings.

Safety: Isolate power and gas. Do not operate with a suspected flue fault.

• Check condensate trap and drain: On condensing Chaffoteaux models, remove the condensate trap, empty and flush it, and ensure the drain hose is clear and correctly routed.
• Inspect flue system: Verify that the flue is correctly assembled, not sagging, and free from obstructions at the terminal.
• Examine pressure switch tubing: Remove the silicone tubes from the air pressure switch and fan connection points. Check for water, cracks, or blockages. Blow through gently to clear any debris and refit securely.
• Test air pressure switch: With a multimeter, check continuity across the switch terminals while the fan runs (requires live testing by a competent person). If the switch does not change state, replace it.
• Check fan operation: If the fan is noisy, slow to start, or does not run, it may be failing and should be replaced.