Common problems guide

The most common Baxi Duo-tec Combi HE A problems

The faults most likely to send a Baxi Duo-tec Combi HE A 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.
19 documented codes
6 most common
2 DIY-safe checks
4 engineer needed

The 6 most common faults

01
E119 High DIY-safe

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

What to try first

Locate the external filling loop, which is usually a flexible silver braided hose connecting two pipes under the boiler.Open the small valve or tap on the filling loop to allow cold mains water to enter the system.Watch the pressure gauge on the front of the boiler and close the valve once the needle reaches between 1.0 and 1.5 bar.

Est. cost
£80-150
Parts
Pressure Relief Valve, Pressure Gauge, Expansion Vessel
Full guide for E119
02
119 High DIY-safe

Your boiler has detected that the water pressure inside the system has dropped too low to operate safely.

What to try first

Locate the external filling loop, which is usually a small silver braided hose with one or two valves located underneath the boiler.Open the valve(s) slowly to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly and check that the error code clears.

Est. cost
£0-£120
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for 119
03
E20 High Engineer

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

Est. cost
£120-200
Parts
Central Heating NTC Sensor, Wiring harness
Full guide for E20
04
E28 High Engineer

Your boiler has detected a faulty sensor that monitors the temperature of the gases leaving your flue, which has caused the boiler to stop working to keep you safe.

Est. cost
£150-250
Parts
Flue NTC Sensor, Wiring Harness
Full guide for E28
05
E50 High Engineer

Your boiler is currently unable to sense the temperature of your hot water, which means it has stopped providing hot water to your taps and shower.

Est. cost
£120-220
Parts
Domestic Hot Water (DHW) NTC Sensor
Full guide for E50
06
E110 High Engineer

Your boiler has detected that it has become dangerously overheated and has automatically shut itself down to prevent damage.

Est. cost
£120-250
Parts
Pump, Diverter Valve, Heat Exchanger
Full guide for E110
Parts most often replaced

on the Baxi Duo-tec Combi HE A

Pressure Relief ValvePressure GaugeExpansion VesselFilling loopPressure relief valvePressure sensor

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 Baxi 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 19-code list for the Baxi Duo-tec Combi HE A

Related guides

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