Common problems guide

The most common Potterton Suprima problems

The faults most likely to send a Potterton Suprima 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.
9 documented codes
6 most common
2 DIY-safe checks
4 engineer needed

The 6 most common faults

01
Lockout High DIY-safe

Your boiler has temporarily stopped working for safety reasons, meaning you currently have no heating or hot water.

What to try first

Check your gas supply by ensuring other gas appliances, like your cooker, are working.Check that your prepay meter (if you have one) has credit.Locate the reset button on your Potterton Suprima and press it firmly for 5 seconds to see if the boiler fires back up.

Est. cost
£100-250
Parts
PCB, Ignition Lead, Gas Valve
Full guide for Lockout
02
Blocking High Engineer

Your boiler has temporarily stopped working because it has detected an issue with the electricity supply frequency or an internal safety switch.

Est. cost
£150-300
Parts
Air Pressure Switch, PCB
Full guide for Blocking
03
Mains ON Only High Engineer

Your boiler has detected an internal fault that has caused it to stop heating your home and hot water for safety reasons.

Est. cost
£150-300
Parts
PCB, Ignition lead, Gas valve
Full guide for Mains ON Only
04
Ext. Call for Heat (Boiler set to STNDBY, Temp. Control set to 'O' Off) High DIY-safe

Your boiler is currently switched off or set to standby mode while your heating controls are still asking it to provide heat.

What to try first

Check the temperature control dial on the front of the Potterton Suprima and turn it up from the 'O' (Off) position.Ensure the boiler mode switch is moved from 'STNDBY' to 'ON' or 'RUN'.Check your external room thermostat or programmer to see if it is correctly scheduled and calling for heat.

Full guide for Ext. Call for Heat (Boiler set to STNDBY, Temp. Control set to 'O' Off)
05
Ignition (i.e. Gas and Sparks ON) High Engineer

Your boiler is trying to start up and producing sparks, but the gas is failing to ignite properly.

Est. cost
£150-300
Parts
Ignition electrode, Gas valve, Printed Circuit Board (PCB)
Full guide for Ignition (i.e. Gas and Sparks ON)
06
Earth Fault Emergency Engineer

Your boiler has detected that the internal electrical wires for the live and neutral supply have been reversed during installation or a recent repair.

Est. cost
£80-150
Parts
Fused Spur, Internal Wiring
Full guide for Earth Fault
Parts most often replaced

on the Potterton Suprima

PCBIgnition LeadGas ValveAir Pressure SwitchIgnition leadGas valve

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 Potterton 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 9-code list for the Potterton Suprima

Related guides

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