!
error Haswill

Error Code E1

The memory unit is broken.

? What Causes This

Memory unit failure or corruption.

How to Fix It

Press any key to restore default data or perform a factory reset.

Source: page 63 of the official manual

From the manual

Manual page 63 — Haswill error E1

This error code appears in:

Haswill Stc 1000 Temperature Controller