Heatline Solaris Fault codes & diagnostics

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

Combi Natural Gas 24-30 kW 2006-2010 Discontinued

Replaced by: Capriz

Choose your boiler type

The Solaris range comes in 2 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

24PC 12 codes · 1 GC number 30PC 12 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

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.
20 High 1 Medium 1 Low
Just want the most common Heatline Solaris faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 22 documented codes

Tap any card for details

0.8bar

Your boiler has detected that the water pressure is too low for it to operate safely and effectively.

High DIY-safe £0-120 Shared across the Solaris range

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the one or two taps/valves until you hear water entering the system.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for 0.8bar
E01

Your boiler has failed to light the gas or cannot confirm a flame is present, meaning it cannot provide heat or hot water.

High DIY-safe £120-350 Shared across the Solaris range

What to check first

  1. Check if your gas supply is active by testing another gas appliance like a hob.
  2. Verify that your credit meter has sufficient funds.
  3. Press the Reset button on the boiler control panel for 3 seconds.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E01
E02

Your boiler has stopped working because it cannot confirm that the fan is safely clearing waste gases from the system.

High Engineer only £120-£250 Shared across the Solaris range

Parts commonly replaced

  • Air pressure switch
  • Fan assembly
  • Venture tube
  • APS silicone tubing

Related codes

Full explanation for E02
E03

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

High DIY-safe £100-250 Shared across the Solaris range

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Ensure your system water pressure is between 1.0 and 1.5 bar on the pressure gauge.
  3. Press the reset button on the control panel to see if the fault clears after the system has cooled down.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Main Heat Exchanger (if blocked)

Related codes

Full explanation for E03
E05

Your boiler has detected an issue with the sensor that monitors the temperature of the water flowing to your radiators, which means it cannot safely heat your home.

High Engineer only £90-160 Shared across the Solaris range

Parts commonly replaced

  • Central heating flow NTC sensor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for E05
E06

Your boiler is struggling to provide hot water correctly because its dedicated temperature sensor has developed a technical fault or stopped working.

Medium Engineer only £90-160 Shared across the Solaris range

Parts commonly replaced

  • DHW Temperature Sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for E06
E09

Your boiler has detected that the water pressure is too low, causing the system to shut down for safety.

High DIY-safe £0-160 Shared across the Solaris range

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath the boiler.
  2. Slowly open the one or two taps on the loop until you hear water entering the system.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor
Full explanation for E09
E12

Your boiler's internal computer brain has suffered a software memory failure and can no longer process instructions.

High Engineer only £280-450 Shared across the Solaris range

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • EEPROM Chip
Full explanation for E12
E15

Your boiler has detected an unusual temperature difference between the water leaving the unit and the water returning to it, often caused by a circulation blockage or a sensor failure.

High Engineer only £120-£350 Shared across the Solaris range

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Circulation pump
  • Main PCB

Related codes

Full explanation for E15
E16

Your boiler has stopped working because one of its internal temperature sensors is providing an incorrect reading or has failed completely.

High Engineer only £90-160 Shared across the Solaris range

Parts commonly replaced

  • Return NTC Thermistor
  • Sensor wiring harness

Related codes

Full explanation for E16
Showing 11–20 of 22
E22

Your boiler's internal computer has lost its settings or is having trouble communicating with the main control board, preventing the system from starting.

High Engineer only £220-450 Shared across the Solaris range

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Full explanation for E22
E77

Your boiler has detected an electrical problem with the parts that control the gas flow, causing it to shut down for safety.

High Engineer only £180-350 Shared across the Solaris range

Parts commonly replaced

  • Gas valve
  • Main PCB (Printed Circuit Board)
  • Wiring harness
Full explanation for E77
F0

Your boiler has stopped working because the water pressure inside the system is too low.

High DIY-safe £0-120 Shared across the Solaris range

What to check first

  1. Locate the flexible filling loop underneath the boiler.
  2. Slowly open the small valves on the loop until you hear water entering the system.
  3. Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for F0
F1

Your boiler has automatically shut down for safety because its internal temperature has climbed too high.

High Engineer only £120-250 Shared across the Solaris range

Parts commonly replaced

  • NTC sensor
  • Primary heat exchanger
  • Pump
  • Overheat thermostat

Related codes

Full explanation for F1
F2

Your boiler is struggling to accurately detect the temperature of your hot water, which means it has stopped heating it up to prevent the system from getting too hot.

High Engineer only £120-220 Shared across the Solaris range

Parts commonly replaced

  • DHW NTC sensor

Related codes

Full explanation for F2
F3

Your boiler has stopped working because it is unable to accurately measure the temperature of the water inside the system.

High Engineer only £120-220 Shared across the Solaris range

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for F3
F4

Your boiler is failing to light the flame needed to produce heat or hot water.

High Engineer only £120-250 Shared across the Solaris range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for F4
F5

Your boiler has detected a fault with a safety sensor that monitors the temperature of the gases leaving your flue, meaning the boiler has shut down to prevent potential overheating.

High Engineer only £150-250 Shared across the Solaris range

Parts commonly replaced

  • Flue gas temperature sensor
  • Wiring harness

Related codes

Full explanation for F5
F6

Your boiler is having trouble communicating with the outside temperature sensor, which helps it run efficiently based on the weather.

Low DIY-safe £70-130 Shared across the Solaris range

What to check first

  1. Locate the external sensor on an outside wall to check for obvious physical damage or loose wires
  2. Turn the boiler power off and back on to see if the fault clears
  3. If the issue persists, the boiler will still provide heat but will revert to standard internal settings

Parts commonly replaced

  • External temperature sensor (Outdoor weather compensator)
  • Wiring harness

Related codes

Full explanation for F6
F7

Your boiler is struggling to confirm that the internal fan is spinning correctly, so it has safely shut itself down to prevent any unsafe operation.

High Engineer only £150-250 Shared across the Solaris range

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F7
Showing 21–22 of 22
F8

Your boiler has detected that the fan, which safely removes waste gases from your home, is not spinning at the correct speed or has stopped working entirely.

High Engineer only £180-£350 Shared across the Solaris range

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Air pressure switch

Related codes

Full explanation for F8
F9

Your boiler has detected that the internal air extraction fan is spinning when it should be switched off, which prevents the system from starting up safely.

High Engineer only £150-250 Shared across the Solaris range

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F9
Status & diagnostic codes

3 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

OC Status Your boiler has detected an outdoor temperature sensor and is adjusting its settings to match the weather outside. S.13 Status Your boiler is failing to light the flame, so it has safely stopped operating to prevent gas from building up inside. S.27 Status Your boiler is simply finishing a final water circulation cycle to safely cool itself down after heating has been running.