Main Ecoinstaller 2 Fault codes & diagnostics

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

Combi Natural Gas 24-28 kW 2010-2015 Discontinued

Replaced by: Main Eco Elite

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15 High
Just want the most common Main Ecoinstaller 2 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 15 documented codes

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24

Your boiler has stopped working because it cannot light the flame or the internal drainage pipe is blocked.

High DIY-safe £80-250

What to check first

  1. Check if the white plastic pipe underneath the boiler is frozen or blocked
  2. Thaw any frozen external pipes with warm (not boiling) water or a heat pad
  3. Locate your gas meter to ensure the gas supply is turned on
  4. Press and hold the Reset button for five seconds

Parts commonly replaced

  • Flame Sensing Electrode
  • Condensate Trap
  • Gas Valve

Related codes

Full explanation for 24
25

Your boiler has effectively switched itself off because it has detected it is getting too hot, likely due to a circulation or blockage issue.

High DIY-safe £120-£350

What to check first

  1. Check that your home's radiator valves are fully open.
  2. Ensure the boiler pressure is between 1 and 1.5 bar on the gauge.
  3. Attempt to reset the boiler using the selector switch.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • External Heating Filter

Related codes

Full explanation for 25
26

Your boiler has stopped working because the fan that removes waste gases is either blocked or not spinning correctly.

High Engineer only £180-£350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Air Pressure Switch

Related codes

Full explanation for 26
27

Your boiler has stopped working because the water pressure is too low or the pump that circulates water around your home is struggling to move.

High DIY-safe £120-350

What to check first

  1. Check the pressure gauge on the front of the boiler; if it is below 1.0 bar, use the filling loop handles to top it up to 1.5 bar.
  2. Ensure all radiator valves are open to allow water to flow.
  3. Restart the boiler once the pressure is restored.

Parts commonly replaced

  • Circulating Pump
  • Expansion Vessel recharge
  • Water Pressure Switch

Related codes

Full explanation for 27
28

Your boiler is having trouble measuring the temperature of your hot water, which usually means your taps and showers will only run cold.

High Engineer only £90-160

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Sensor
  • Sensor wiring harness

Related codes

Full explanation for 28
29

Your boiler has detected a problem with the sensor that monitors the temperature for your radiators, causing the heating to stop working.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating (Flow) NTC Sensor
  • Connecting Wiring Harness

Related codes

Full explanation for 29
E20

Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has safely shut itself down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • Central Heating NTC Sensor
  • Wiring harness
Full explanation for E20
E28

Your boiler's computer module has been identified as the wrong type for your specific heating system, preventing it from operating correctly.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for E28
E50

Your boiler is struggling to accurately measure the temperature of the water being heated for your taps and shower, so it has stopped working to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Hot Water NTC Sensor
  • Wiring Harness
Full explanation for E50
E110

Your boiler has detected that it is overheating and has automatically switched itself off to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Safety Thermostat
  • NTC Sensor
  • Circulation Pump
  • Diverter Valve

Related codes

Full explanation for E110
E119

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a silver flexi-hose with valves) underneath the boiler or nearby pipework.
  2. Open the valves slowly to allow mains water into the system while watching the pressure gauge on the front of the boiler.
  3. Stop filling once the needle reaches 1.5 bar on the gauge and ensure both valves are firmly closed.

Parts commonly replaced

  • Pressure Relief Valve
  • Pressure Sensor
  • Expansion Vessel
Full explanation for E119
E125

Your boiler is struggling to pump water around your heating system, which is preventing it from heating up your home or water properly.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Flow sensor
  • Diverter valve

Related codes

Full explanation for E125
E130

Your boiler has detected that the temperature of the exhaust gases is too high, causing it to shut down for safety.

High Engineer only £150-300

Parts commonly replaced

  • Flue gas sensor
  • NTC sensor
  • Heat exchanger

Related codes

Full explanation for E130
E133

Your boiler is failing to light because it cannot detect a steady flame or is not receiving enough gas to stay running.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

Full explanation for E133
E160

Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not spinning, so it has shut down to prevent unsafe operation.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
Full explanation for E160