Verified boiler fault code

Warmflow E01 Fault Code (Agentis Boilers (B-Series, I-Series and E-Series))

Burner lockout.

Safety disclaimer

Boiler repair help from Aza & Sons Services

Fault code summary

Manufacturer: Warmflow
Fault code: E01
Fault type: Safety lockout, Flame failure, Fuel supply
Severity: high
Reset: The manual identifies this as a service-engineer fault; do not repeatedly press the burner reset button.
Applicable models: B21, B26, B33, I21, I26, I33, I44, I21PRO, I26PRO, I33PRO, I44PRO, I21P/PRO, I26P/PRO, I33P/PRO, I44P, I21S/PRO, I26S/PRO, I33S/PRO, I21C/PRO, I26C/PRO, I33C/PRO, E21, E26, E33, E44, E21PRO, E26PRO, E33PRO, E44PRO, E21P/PRO, E26P/PRO, E33P/PRO, E44P, E21S/PRO, E26S/PRO, E33S/PRO, E21C/PRO, E26C/PRO, E33C/PRO

Quick answer

Burner lockout.

What does this fault code mean?

Burner lockout.

Common causes

No fuel supply to burner
Air in fuel lines
Burner fault

Symptoms

E01 displayed on the LCD
Burner lockout

What can the homeowner safely check?

Check the external oil supply has not been deliberately isolated and record the code; do not work on the burner or fuel system.

Boiler reset information

The manual identifies this as a service-engineer fault; do not repeatedly press the burner reset button.

When should I call an engineer?

Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.

Engineer diagnosis

An OFTEC-registered or otherwise suitably qualified engineer should investigate fuel supply, air in the fuel line and burner operation.

Applicable boiler models

Related fault codes

Manufacturer documentation

Warmflow Agentis Boiler Manual 6572 G

Last verified

2026-09-12

Frequently asked questions

What does Warmflow E01 mean?

Burner lockout.

Can I reset a Warmflow E01 fault?

The manual identifies this as a service-engineer fault; do not repeatedly press the burner reset button.