How to Read Your Boiler's Error Codes

When your boiler stops working and shows a code on its display, that code is a diagnostic message — not a random error. Here's how to read them and what to do.

Finding your error code

Most modern boilers display the error code on the main display panel. Some older models have LED indicator lights rather than a numeric display — consult your boiler manual for those. Note the code before attempting a reset.

Worcester Bosch Greenstar codes

• F.22 / EA 222: Low water pressure — re-pressurise to 1–1.5 bar, then reset
• EA 229: Ignition fault — reset once. If persistent, Gas Safe engineer required
• F.28: Ignition failure — check other gas appliances work first
• F.75: Pressure sensor fault — engineer required

Vaillant ecoTEC codes

• F.22: Low pressure — re-pressurise, then reset. Most common Vaillant lockout
• F.28: Ignition failure — engineer required if persistent after one reset
• F.75: Pump or pressure sensor fault — engineer required

Ideal Logic Max codes

• F1: Low pressure — re-pressurise first
• F2: Flame failure — reset once, engineer if persistent
• L1: Overheat — check pressure and bleed radiators

Baxi 800 codes

• E168: Low gas pressure — check other appliances
• E160: Overheat — check for airlocks and correct pressure
• E110: Safety device operated — engineer required

General rule

Attempt a reset once after addressing any obvious issues (low pressure, frozen condensate). If the code returns within an hour, call a Gas Safe engineer — don't keep resetting. Book a repair with Corby Boiler Installations.