| E01 | Safety lockout due to ignition failure. | If the gas valve BI1013108 does not open/modulate, gas does not reach the burner and the boiler does not ionise; check the control voltage at the valve and pressure at the inlet/outlet ports during the ignition attempt. |
| E11 | Presence of parasitic flame. | A gas valve that does not close tightly may allow gas to pass ('let-by') and maintain a flame signal with the burner off; check the valve's tightness (leak test/manometer) and rule out leakage to the burner after the closure command. |
| E20 | EVG lockout (gas valve control hardware fault). | Fault in the solenoid/modulator of the BI1013108 valve or its operation; measure resistance of coils/modulator, presence of control signal/voltage, and continuity of wiring to the valve. |
| E22 | EVG lockout (flame after gas valve shut-off Ref. EVG). | Defective closure of the gas valve allowing flame after the closure command; verify that the valve closes without residual flow (manometer on manifold/ionisation after closure) and replace if it allows gas to pass. |
| E23 | Gas valve modulator disconnected. | Connector or modulating coil of the BI1013108 valve in open circuit/disconnected; check plug/modulator, continuity, and control signal (0–10 V or PWM depending on model). |
| E44 | Accumulated timeout anomaly of the gas valve without flame. | The gas valve does not open/modulate in time (stuck or slow response) and retries accumulate without flame; check control voltage, opening times, and inlet pressure while it attempts to ignite. |