12-66 Low
Your boiler is having trouble detecting the steady flame it needs to run safely, but it may just be a temporary sensing error.
Technical description: Ion base value lower than the upper factory limit, try resetting the boiler
Typical repair cost: £100-220 (including labour)
DIY fix possible
Locate the reset button (usually a circular arrow or 'Reset' text) on the control panel.Press and hold the reset button for five seconds.Wait for the boiler to restart and monitor if the code clears.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 12-66 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- Ionisation electrode
- Ignition lead
- Burner gasket
*Affiliate links — we may earn a commission at no extra cost to you.