BoilerFaultCodesThe 6 most common faults
01
E040 High DIY-safe
Your boiler is struggling because it cannot detect enough water in the system to operate safely.
What to try first
Locate the filling loop under your boilerOpen the valves to allow water into the systemMonitor the pressure gauge on the front of the boiler until it reads between 1.0 and 1.5 barClose the valves tightly
02
E041 High DIY-safe
Your boiler has detected that the water pressure inside the system is currently too low to operate safely.
What to try first
Locate the filling loop (a silver flexi-pipe with valves) underneath your boiler.Open the valves slowly to allow mains water to enter the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually 1.0 to 1.5 bar).Close the valves tightly.
03
E010 High Engineer
Your boiler has failed to light the flame properly and has safely shut itself down to prevent gas from building up.
Full guide for E01004
E020 High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Full guide for E02005
E030 High Engineer
Your boiler has detected an issue with the internal ventilation system that removes exhaust gases, so it has shut down as a safety precaution.
Full guide for E03006
E042 High Engineer
Your boiler is struggling to detect the flow or pressure of water moving through the system, which is preventing it from heating your home properly.
Full guide for E042on the Vokera Unica MAX
Water pressure sensorPressure relief valvePressure TransducerPressure Relief ValveFilling LoopIgnition electrode
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Vokera shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue
Boiler cover options
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.