Common problems guide

The most common Johnson Starley Aquair S problems

The faults most likely to send a Johnson Starley Aquair S 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.
3 documented codes
3 most common
0 DIY-safe checks
3 engineer needed

The 3 most common faults

01
E01 High Engineer

Your boiler is trying to start but cannot light the flame, so it has shut down to keep your home safe.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, Control board
Full guide for E01
02
E03 High Engineer

Your boiler has detected a communication issue with a sensor that monitors the temperature of the exhaust gases, causing it to shut down for safety reasons.

Est. cost
£150-250
Parts
Flue gas temperature sensor, Wiring harness
Full guide for E03
03
E22 High Engineer

Your boiler's electronic control brain is struggling to process its internal settings, causing it to stop运行 safely to prevent potential incorrect operation.

Est. cost
£250-450
Parts
Main PCB, EEPROM chip
Full guide for E22
Parts most often replaced

on the Johnson Starley Aquair S

Ignition electrodeGas valveControl boardFlame probeFlue gas temperature sensorWiring 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 Johnson Starley 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 3-code list for the Johnson Starley Aquair S

Related guides

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