BoilerBuddy · Main Heating guide

Main Heating boiler fault codes and symptoms

BoilerBuddy helps you diagnose boiler problems, work through minor checks, and escalate major problems to a Gas Safe engineer. Start with the exact code and range shown on your appliance; meanings can differ between models.

From the fault-code directory

Common Main Heating codes and symptoms

These examples link to existing records for their specific boiler ranges. Open the matching record for its full context and guidance.

  • Eco Compact Combi 25–30

    Code 118: 118

    Primary system water pressure too low.

  • Eco Compact Combi 25–30

    Code 110: 110

    Safety thermostat operated.

  • Eco Compact Combi 25–30

    Code 125: 125

    Primary circulation fault.

  • Eco Compact Combi 25–30

    Code 133: 133

    133 indicates an interruption of gas supply or flame failure.