Common problems guide

The most common Alpha Cd13r problems

The faults most likely to send a Alpha Cd13r 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.
18 documented codes
6 most common
2 DIY-safe checks
4 engineer needed

The 6 most common faults

01
E10 High DIY-safe

Your boiler has stopped working because the amount of water pressure in your heating system has dropped too low to operate safely.

What to try first

Locate the external filling loop, usually a silver braided hose with one or two valves located underneath your boiler.Gradually open the valve(s) 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) firmly and ensure the boiler resets itself or switch it off and on again.

Est. cost
£0-£100
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for E10
02
E04 High DIY-safe

Your boiler has switched off because the water level inside your central heating system has dropped too low to operate safely.

What to try first

Locate the external filling loop, which is a silver braided hose with one or two valves connecting your mains water pipe to the heating pipework.Open the valve(s) slowly to allow water into the system while watching the pressure gauge on the front of the boiler.Close the valve(s) firmly once the needle on the pressure gauge reaches the green zone, typically between 1.0 and 1.5 bar.

Est. cost
£80-150
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for E04
03
Neon D High Engineer

Your boiler has lost its power connection, meaning it cannot start up or provide any heating and hot water.

Est. cost
£120-250
Parts
Main PCB, Internal fuse, Wiring harness
Full guide for Neon D
04
C1 High Engineer

Your boiler has stopped working because it is unable to accurately measure the temperature of the water returning to it, so it has shut down as a precaution.

Est. cost
£120-220
Parts
Return NTC Thermistor, Wiring harness
Full guide for C1
05
C2 High Engineer

Your boiler has stopped working because a sensor that monitors the water temperature inside your heating system is giving incorrect or no information to the control board.

Est. cost
£120-200
Parts
NTC Temperature Sensor, Wiring harness
Full guide for C2
06
E01 High Engineer

Your boiler has failed to light the gas flame required to provide heating or hot water.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, Printed circuit board (PCB)
Full guide for E01
Parts most often replaced

on the Alpha Cd13r

Filling loopPressure relief valvePressure sensorMain PCBInternal fuseWiring harness

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 Alpha 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 18-code list for the Alpha Cd13r

Related guides

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