Alpha · E-Tec Plus
37Supply voltage too low
This code applies to E-Tec Plus 28, E-Tec Plus 33, E-Tec Plus 38. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.
What you can safely check
- Check for a wider power cut or a tripped consumer-unit circuit without removing the boiler case.
- Use a qualified electrician or Gas Safe engineer for further diagnosis.
How an engineer may fix it
Verify supply voltage, polarity, earthing, fuses, harnesses and appliance electronics; correct the electrical supply or replace the failed component.
Manufacturer source: Alpha Heating Innovation — E-Tec Plus Installation and Servicing Instructions (01/22). Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.