Boiler Fault Codes: What Do They Mean?

What Are Boiler Fault Codes?

Modern boilers have built-in diagnostic systems that display fault codes when something goes wrong. These alphanumeric codes appear on the boiler's display panel and give engineers (and knowledgeable homeowners) a starting point for diagnosis.

Fault codes vary by manufacturer — an F22 on a Vaillant means something completely different from an F22 on a Baxi. Always check your specific boiler manual, but here's a general guide to the most common codes.

Worcester Bosch Fault Codes

|------|---------|--------|

Vaillant Fault Codes

|------|---------|--------|

Ideal Boiler Fault Codes

|------|---------|--------|

Baxi Fault Codes

|------|---------|--------|

What to Do When You See a Fault Code

1. Note the code before attempting anything

2. Check your manual or the manufacturer's website for the specific meaning

3. Try the recommended action (e.g., repressurising, thawing)

4. Press reset and monitor for 10–15 minutes

5. If the fault returns, call an engineer — repeated fault codes indicate an underlying problem

Never ignore persistent fault codes. They're your boiler telling you something is wrong.

For expert fault diagnosis and repair, call Halo Heating on 01483 676108. Our Gas Safe engineers carry the most common boiler parts on their vans for fast, first-visit fixes.