Boiler shows A1 and stops, often during or after heavy rain or freezing conditions, condensate may not be draining.

Safety first: Turn off power before working on condensate components. Condensate is mildly acidic; wear gloves and eye protection.

Homeowner checks (safe):

• If the condensate pipe runs outside, check for ice. Thaw gently with warm water and a warm cloth; do not use boiling water or open flame.
• Once thawed, reset the boiler and observe operation.

Engineer checks:

• Remove and clean the Worcester condensate trap, flushing out debris and refilling with clean water.
• Inspect internal condensate hoses for kinks or blockages.
• If an internal condensate pump is fitted, test its operation and replace if not pumping.
• Verify correct fall and support of the external condensate pipe to prevent future freezing.

Persistent A1 errors after thawing indicate internal blockage or pump issues that require an engineer.