Boiler attempts to start but shuts down with fault code E02, fan runs but no ignition sequence continues.

Safety first: Isolate electrical power to the boiler. Do not operate the boiler with a blocked flue or intake.

• Inspect flue and air intake: From outside, check that the flue terminal and combustion air intake are free of leaves, nests, snow, or other obstructions. Clear any blockage.
• Check condensate in tubing: Open the boiler casing and locate the air pressure switch and its silicone tubes. Look for water or debris inside the tubes. If present, remove the tubes, blow them through gently, and refit securely.
• Verify fan operation: Restore power and start the boiler while observing the fan. If the fan does not run or is noisy or slow, the fan motor or capacitor may be failing and should be replaced.
• Test air pressure switch: With power off, disconnect the wires from the air pressure switch and check continuity with a multimeter while gently applying suction/pressure to the tubing. If the switch does not change state, replace it with the correct Weishaupt part.

When to call a professional: If the flue system is damaged, if the fan needs replacement, or if you cannot verify safe combustion air flow, contact an authorised Weishaupt technician.