Evo HE C22/30 Fault codes & diagnostics

9 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 30 kW 2003 onwards Discontinued
GC Number 47-348-33
Download the Evo HE C22/30 manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
9 High
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-348-33 HE C22/30 HE C22/30 2003–present
Just want the most common Evo HE C22/30 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 9 documented codes

Tap any card for details

93

Your boiler is struggling to detect the flame it has lit, causing the system to shut down for safety.

High DIY-safe £100-£280

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your gas meter
  2. Test if other gas appliances in the home, such as a hob, are working correctly
  3. Press the reset button once to see if the boiler restarts

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve

Related codes

Full explanation for 93
94

Your boiler has detected that the electrical wiring coming from your power supply is reversed, meaning the live and neutral wires are currently swapped.

High Engineer only £80-160

Parts commonly replaced

  • Mains power cable
  • Control PCB

Related codes

Full explanation for 94
H E

Your boiler has detected an internal communication error between the main control board and its display or ignition system, preventing it from starting up.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB
  • Internal Wiring Loom

Related codes

Full explanation for H E
H9

Your boiler has detected a potential internal issue that requires a specific sequence of technical checks to determine the exact cause.

High Engineer only £100-£350

Parts commonly replaced

  • Main PCB
  • Flow/Return Thermistors
  • Wiring Harness

Related codes

Full explanation for H9
H9/L9

Your boiler has shut down because the internal water temperature has become too hot, causing it to lock out for safety.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar
  3. Try resetting the boiler once the unit has cooled down

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Main Heat Exchanger

Related codes

Full explanation for H9/L9
L A

Your boiler has failed to ignite after several attempts, meaning you will not have any heating or hot water until the system is reset or repaired.

High DIY-safe £120-£350

What to check first

  1. Check that your gas emergency control valve is in the 'on' position and you have credit on your meter.
  2. Press the 'Reset' button on the boiler control panel for two seconds.
  3. Ensure the condensate pipe (the plastic pipe leading outside) is not frozen if it is currently very cold weather.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Flame Sensing Electrode
  • Printed Circuit Board (PCB)

Related codes

Full explanation for L A
L E

Your boiler has failed to ignite after several attempts, meaning the system cannot provide heating or hot water until it is reset.

High DIY-safe £100-350

What to check first

  1. Check that your gas supply is turned on (check other gas appliances like your hob).
  2. Press and hold the 'Reset' button for five seconds.
  3. If the boiler has been off for a long time, repeat the reset process up to three times to clear air from the pipes.

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve

Related codes

Full explanation for L E
L9

Your boiler has likely overheated or is struggling to circulate water, causing it to shut down for safety.

High Engineer only £180-350

Parts commonly replaced

  • Circulation pump
  • Overheat thermostat
  • Main heat exchanger (cleaning or replacement)

Related codes

Full explanation for L9
LA/HA

Your boiler has become too hot and has shut down as a safety precaution to prevent damage.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar
  3. Wait for the unit to cool down below 50°C before attempting to reset

Parts commonly replaced

  • Circulation Pump
  • Heat Exchanger (de-sludging)
  • Overheat Thermostat

Related codes

Full explanation for LA/HA