C4 273 — Airflow present / continuous fan operation

What does C4 273 mean?

This indicates that airflow was present continuously for the last 24 hours, or the boiler was switched off for a short period due to continuous operation. The appliance may be temporarily blocked.

• Continuous fan operation due to a fault.
• Control system anomaly.
• Blocked flue or air intake.

Click steps to track your progress.

1. 1

   Reset the boiler by power cycling it at the mains.

2. 2

   Check for any visible obstructions around the flue terminal outside your property.

3. 3

   If the boiler temporarily blocks or the fan runs continuously, contact a Gas Safe registered engineer for inspection.