A08Vokera
Vokera A08: return thermistor fault
Checked against Vokera's own documentation: Vokera Vision combi user, installation and servicing instructions and 1 more source. Last reviewed October 2026. How we check
Engineer only
The sensor that measures the temperature of water returning to the boiler has a fault.
What you can safely do
There is nothing you can safely do yourself with this one. Leave the boiler off and book an engineer.
Before you book an engineer
- Write down the code exactly as the display shows it: A08.
- Find your boiler's model name. It is usually on the front panel or in the user manual. The table below shows why it matters: Vokera codes can mean different things on different models.
- Note when it started and what the boiler was doing (heating, hot water, or starting up).
- If the boiler is still under warranty, check your warranty paperwork before you book anyone.
Call a Gas Safe engineer if
- Book a Gas Safe registered engineer.
Find a Gas Safe engineer near you
Opens the official Gas Safe Register search.
Applies to Vision and Compact A. Codes can differ between models, so check your manual.