Error code
Worcester Bosch Boiler 224 — Meaning and Safe Advice
On the documented Greenstar models, 224 is a temperature-limiter lockout. Confirmed for the Greenstar 8000+ and 8000+ Style models covered by manual 6721891026 (2024/06), not every Worcester boiler. Record any accompanying letters or subcodes.
Quick answer
224: Flue-gas or heat-exchanger temperature limiter activated
Meaning
Flue-gas or heat-exchanger temperature limiter activated
First safe check
Record the full model number and complete displayed code before attempting a remedy.
Stop if
The warning is active or recurring and the next step would require internal access.
Who to call
Contact a Gas Safe registered engineer qualified for the boiler with the model and full code. The display identifies a reported condition, not a confirmed replacement part.
Internal diagnosis and repair require a qualified professional. Follow only the model-approved user actions described below. Keep checks outside the casing and use only a manufacturer-approved reset where the manual allows it.
What does this error code mean?
On the documented Greenstar models, 224 is a temperature-limiter lockout.
A low-pressure-only diagnosis is incorrect; pressure is only one of several professional checks in the manual.
Confirmed for the Greenstar 8000+ and 8000+ Style models covered by manual 6721891026 (2024/06), not every Worcester boiler. Record any accompanying letters or subcodes.
Why is this happening?
- The manufacturer-reported condition is: flue-gas or heat-exchanger temperature limiter activated. An engineer must establish the underlying cause on the actual model.
Safe next steps
- Record the full model number and complete displayed code before attempting a remedy.
- Confirm that the manufacturer guidance below applies to that model. Do not use instructions for a different appliance or code suffix.
- Contact a Gas Safe registered engineer qualified for the boiler for diagnosis if the warning is active or recurring.
Can I fix this myself?
NoLimit your actions to the external checks and model guidance described here; internal diagnosis requires a professional.
Safety boundary: Do not remove the boiler casing or work on gas, combustion, flue components or internal wiring.
What not to do
- Do not remove the boiler casing or work on gas, combustion, flue components or internal wiring.
- Do not order replacement parts solely from the code or repeat resets to suppress a returning warning.
Common misdiagnoses
- A low-pressure-only diagnosis is incorrect; pressure is only one of several professional checks in the manual.
When to call a heating professional
Contact a Gas Safe registered engineer qualified for the boiler with the model and full code. The display identifies a reported condition, not a confirmed replacement part.
Safety warning
Do not remove the boiler casing or work on gas, combustion, flue components or internal wiring.
Useful hub links
Other Worcester Bosch boiler codes
Worcester Bosch Boiler 227 — Meaning and Safe Advice
No flame signal after ignition
Worcester Bosch Boiler 229 — Meaning and Safe Advice
Flame failed during burner operation
Worcester Bosch Boiler D1 — Code Meaning
Return sensor or return-temperature fault; cause code required
Worcester Bosch Boiler E9 — Code Meaning
Temperature safety or related protection fault; cause code required
Relevant guide
Frequently asked questions
Does 224 prove that a part needs replacement?+
No. Match the model and full code first. The manufacturer definition describes the reported condition; diagnosis establishes whether a repair is needed.
Does this definition apply to every model?+
Confirmed for the Greenstar 8000+ and 8000+ Style models covered by manual 6721891026 (2024/06), not every Worcester boiler. Record any accompanying letters or subcodes.
Sources and review status
Model dependent · Last reviewed 21 September 2026
- Worcester Greenstar 8000+ / 8000+ Style manual 6721891026, pages 74–76
model manual · UK · checked 21 September 2026
The code definition and stated model/region scope. A low-pressure-only diagnosis is incorrect; pressure is only one of several professional checks in the manual.