E9 Boiler Fault Code: What It Means on Every Brand

E9 is an overheat (safety temperature limiter) lockout on Worcester Bosch — often with a sub-code such as E9 276 — and a circulation fault on Remeha. Both come back to water not moving through the heat exchanger: check pressure, bleed radiators, then an engineer for the pump, filter or sensor.

Lockout — engineer likely 2 brands use this code

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What E9 means	Severity	DIY?
RRemeha	The E9 fault code on Remeha boilers signals that the appliance has detected a problem with water circulation or system pressure — either the boiler cannot sense enough water in the system,… Full guide →	Lockout — engineer likely	Some checks
WBWorcester Bosch	The E9 fault code means the safety temperature limiter on your central heating flow circuit has tripped. Full guide →	Lockout — engineer likely	No

E9 brand by brand

Remeha E9

The E9 fault code on Remeha boilers signals that the appliance has detected a problem with water circulation or system pressure — either the boiler cannot sense enough water in the system, or the pump isn't moving it around as it should. In most cases the boiler will lock out and stop producing heat or hot water until the underlying issue is resolved. On certain Remeha models the trigger is specifically linked to a safety temperature limiter on the heat exchanger tripping due to insufficient flow, while on others (particularly the Avanta Plus range) it points more directly to the pressure sensing circuit or circulation pump. Regardless of model, the end result is the same: the boiler has decided it cannot operate safely and has shut itself down.

Causes, fixes & costs for Remeha E9 → · All Remeha codes

Worcester Bosch E9

The E9 fault code means the safety temperature limiter on your central heating flow circuit has tripped. Your boiler constantly monitors water temperature, and if it detects that the flow temperature is approaching or exceeding roughly 105°C, it shuts itself down automatically to protect internal components from heat damage. This is a deliberate safety lockout, not a catastrophic failure — but the underlying cause must be identified before the boiler is restarted. On older Worcester Bosch models, you may see a numeric cause code displayed alongside E9: code 219 points toward a heat exchanger problem, while codes 220 or 221 suggest the safety limiter itself may be faulty. On Greenstar 8000 series boilers, the equivalent fault is displayed as 224 V. The combined code you see on the display will help a Gas Safe engineer narrow down the root cause quickly.

Causes, fixes & costs for Worcester Bosch E9 → · All Worcester Bosch codes

Frequently asked questions

Is the E9 fault code the same on every boiler?

Broadly, yes — on Remeha and Worcester Bosch the E9 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.

Can I fix a E9 fault myself?

On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. The underlying repair usually needs a registered engineer. Never open the boiler casing yourself.

Who should I call about a E9 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.