Common problems guide

The most common Remeha Gas 620-510 problems

The faults most likely to send a Remeha Gas 620-510 into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.
8 documented codes
6 most common
3 DIY-safe checks
3 engineer needed

The 6 most common faults

01
6.4.1 Flame control High DIY-safe

Your boiler has stopped working because it cannot detect a flame, causing the system to shut down for safety.

What to try first

Check if other gas appliances, like a cooker, are working to ensure gas supply is activeCheck that your gas meter has credit if you have a pre-payment meterPress the 'Reset' button on the control panel to see if the boiler restarts

Est. cost
£120-350
Parts
Ionisation probe, Ignition electrode, Gas valve
Full guide for 6.4.1 Flame control
02
Flame failure: lock out High DIY-safe

Your boiler has stopped working because it cannot detect a steady flame and has shut itself down as a safety precaution.

What to try first

Check if other gas appliances in your home, such as a gas hob, are working correctly to ensure gas is reaching the property.Ensure your gas meter has credit if you are on a prepayment meter.Press the reset button once to see if the boiler restarts, but do not attempt to reset it more than twice if it fails.

Est. cost
£120-450
Parts
Gas pressure switch, Ignition electrode, Ionisation probe
Full guide for Flame failure: lock out
03
Water level control: lock out High DIY-safe

Your boiler has switched itself off because it cannot properly detect the water level, which is a safety measure to prevent the system from running dry.

What to try first

Locate the instrument panel on the front of the boiler.Press the 'Reset' button firmly once to see if the error clears.If the boiler restarts and runs normally, monitor it; if it locks out again immediately, you must call an engineer.

Est. cost
£120-250
Parts
Water level electrode, Wiring harness, Ignition/Ionisation lead
Full guide for Water level control: lock out
04
6.4.2 Thermostats High Engineer

Your boiler has switched itself off because its internal safety sensors have detected that it is getting too hot.

Est. cost
£180-450
Parts
Safety Thermostat, Safety Temperature Sensor, Heat Exchanger
Full guide for 6.4.2 Thermostats
05
6.4.3 Water level control High Engineer

Your boiler has shut down because it has detected that the water levels inside the system are too low to operate safely.

Est. cost
£180-450
Parts
Water level sensor, Low water pressure switch, Main PCB
Full guide for 6.4.3 Water level control
06
red zone High Engineer

Your boiler is struggling to keep its internal pilot flame lit, which means the system cannot safely start up to provide heating.

Est. cost
£180-450
Parts
Ionisation probe, Ignition electrode, Gas valve
Full guide for red zone
Parts most often replaced

on the Remeha Gas 620-510

Ionisation probeIgnition electrodeGas valveGas pressure switchWater level electrodeWiring harness

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 Remeha 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
See the full 8-code list for the Remeha Gas 620-510

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →