Boiler Showing an Error Code? Here’s What It Might Be Telling You

If your boiler has stopped working and there’s a flashing error code on the display, don’t worry — you’re not alone. Most modern boilers are designed to shut down automatically when something’s wrong and show you a code to help diagnose the issue.

Here are three of the most common boiler error codes we see — and what they mean:

1. F22 (Vaillant) — Low Water Pressure
   If you see F22, your boiler pressure is probably too low. Check your pressure gauge — if it’s below 1.0 bar, you’ll need to repressurise the system. Follow our step-by-step guide here.

2. E133 (Ideal) — Ignition or Gas Issue
   This means your boiler couldn’t light. It might be due to a temporary gas supply issue, a blocked flue, or a frozen condensate pipe in winter. If you smell gas, turn everything off and call the emergency number.

3. F75 (Vaillant) — Pump or Pressure Sensor Fault
   This one’s more complex — your boiler may not be detecting water flow when the pump starts. You’ll need a qualified engineer to take a look.

When to Call an Engineer:

Some codes can be resolved by topping up pressure or resetting the boiler. But if the same code keeps appearing, or you’re unsure what it means — don’t risk it. Book a service with a Gas Safe registered engineer.

Watch our full video breakdown: “What Does That Boiler Error Code Mean?”