Worcester Bosch · Greenstar CDi Classic ErP Combi

A1 boiler fault code

Greenstar CDi Classic ErP Combi

Get a Gas Safe engineer

Free. Enter your postcode.

What A1 means

Pump has run dry or pump has stalled/seized.

Gas Safe engineer: If pressure drops again, is not low, or the code remains, contact a Gas Safe registered engineer.

A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, or someone has possible carbon-monoxide symptoms, leave and call 0800 111 999 from outside.

Safe check

Check the pressure gauge. If it is below 1 bar, top up to about 1.5 bar using the filling loop as shown by the installer/user guide, without removing a panel or casing. Press Reset once only. If pressure drops again, is not low, or the code remains, contact a Gas Safe registered engineer.

When to contact an engineer

If pressure drops again, is not low, or the code remains, contact a Gas Safe registered engineer.

Source and provenance

Greenstar CDi Classic ErP Installation, commissioning and servicing instructions 6 720 815 725 (2015/11) · §7.2 Fault finding, Table 17, printed p. 54
installation and service instructions
2015/11 · 6 720 815 725

Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.

Did this fix it?

After: Repressurise the boiler