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.
21 documented codes
6 most common
1 DIY-safe checks
5 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 hose connected between two pipes under your boiler.Open the small valve knobs on both ends of the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically between 1.0 and 1.5 bar), then tightly close both valves.

Est. cost
£80-150
Parts
Pressure relief valve, Pressure gauge, Filling loop
Full guide for E119
02
E20 High Engineer

Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has shut down as a precaution.

Est. cost
£120-220
Parts
Central Heating NTC sensor, Wiring harness
Full guide for E20
03
E28 High Engineer

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

Est. cost
£120-220
Parts
Flue NTC sensor, Wiring harness
Full guide for E28
04
E110 High Engineer

Your boiler has detected that it has become dangerously hot and has automatically shut down to prevent damage or fire risk.

Est. cost
£120-250
Parts
Pump, Diverter valve, Primary heat exchanger
Full guide for E110
05
E125 High Engineer

Your boiler is struggling to move water around your heating system correctly, which is preventing it from working safely.

Est. cost
£150-350
Parts
Central Heating Pump, Diverter Valve, System Filter
Full guide for E125
06
E130 High Engineer

Your boiler has detected that the exhaust gases are becoming too hot near the flue, so it has shut itself down to prevent any damage.

Est. cost
£150-300
Parts
Flue NTC sensor, Primary heat exchanger, Pump
Full guide for E130
Parts most often replaced

on the Baxi Duo-tec Combi HE A

Pressure relief valvePressure gaugeFilling loopCentral Heating NTC sensorWiring harnessFlue NTC 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 21-code list for the Baxi Duo-tec Combi HE A

Related guides

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