Chaffoteaux Celtic 2 24 Rsc Fault codes & diagnostics

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

Combi Natural Gas 24 kW Discontinued
GC Numbers 47-980-0347-980-07
Download the Chaffoteaux Celtic 2 24 Rsc manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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.
11 High 2 Medium
Just want the most common Chaffoteaux Celtic 2 24 Rsc faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 13 documented codes

Tap any card for details

2a

Your boiler is making loud noises because the water pressure inside your heating system has dropped too low to operate correctly.

High DIY-safe £0-90

What to check first

  1. Locate the external filling loop, which is a silver braided hose with one or two valves located underneath your boiler.
  2. Gradually open the valve(s) to allow mains water into the system while watching the pressure gauge on the front panel.
  3. Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, and ensure the valves are fully closed.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
Full explanation for 2a
2b

Your boiler is struggling to circulate water, which is causing a loud noise because the internal pump has stopped working.

High Engineer only £150-250

Parts commonly replaced

  • Central heating pump
  • Pump capacitor
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 2b
5.iv

Your boiler is struggling to provide hot water properly because an internal component inside the burner area was incorrectly installed or replaced.

High Engineer only £150-250

Parts commonly replaced

  • Venturi
  • Fan assembly
  • Burner manifold seal
Full explanation for 5.iv
5.v

Your boiler has stopped providing hot water because a sensor is no longer correctly reading the water temperature.

High Engineer only £150-250

Parts commonly replaced

  • Domestic Hot Water Thermostat
  • NTC Sensor
Full explanation for 5.v
6.iv

Your boiler is failing to light the burner because it cannot detect that water is moving through the system to provide heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Flow switch
  • Diverter valve diaphragm

Related codes

Full explanation for 6.iv
7.i

Your boiler has detected that the water pressure inside your heating system has become too high, causing a safety valve to release water to prevent damage.

High Engineer only £120-220

Parts commonly replaced

  • Pressure relief valve
  • Expansion vessel
  • Filling loop
Full explanation for 7.i
7.iv

Your boiler is leaking internally, which is causing pressure to build up and trigger a safety drain to prevent damage.

High Engineer only £250-450

Parts commonly replaced

  • Plate-to-plate heat exchanger
  • Pressure relief valve

Related codes

Full explanation for 7.iv
10

Your boiler is struggling to maintain a steady temperature, causing it to turn on and off rapidly instead of staying on consistently.

Medium Engineer only £150-300

Parts commonly replaced

  • NTC thermistor
  • Primary heat exchanger
  • Circulation pump

Related codes

Full explanation for 10
10.iii

Your boiler is struggling to maintain a steady temperature, causing it to turn on and off rapidly because water isn't moving through your heating system correctly.

Medium Engineer only £120-250

Parts commonly replaced

  • Automatic bypass valve
  • Central heating pump
  • System filter

Related codes

Full explanation for 10.iii
10.iv

Your boiler is struggling to move heat away efficiently and is turning itself on and off rapidly to prevent overheating due to a blockage inside.

High Engineer only £150-350

Parts commonly replaced

  • Primary heat exchanger
  • System filter
  • Diverter valve

Related codes

Full explanation for 10.iv
12

Your boiler has lost the correct water pressure needed to run efficiently and will not provide heating or hot water until this is corrected.

High DIY-safe £80-150

What to check first

  1. Locate the external filling loop, usually a small silver braided hose with one or two valves located underneath the boiler.
  2. Gradually open the valve(s) to allow mains water into the system while watching the pressure gauge on the front of the boiler.
  3. Close the valve(s) securely once the needle reaches the green zone, typically between 1 and 1.5 bar.

Parts commonly replaced

  • Pressure Relief Valve
  • Pressure Sensor
  • Expansion Vessel

Related codes

Full explanation for 12
13

Your boiler is picking up excess water pressure, which suggests water is leaking internally into the heating system where it shouldn't be.

High Engineer only £150-300

Parts commonly replaced

  • Filling loop
  • Plate heat exchanger

Related codes

Full explanation for 13
PUMP NOT RUNNING

Your boiler's water pump is failing to start, which means the system cannot circulate hot water to your radiators or taps.

High Engineer only £120-250

Parts commonly replaced

  • Circulating pump
  • Diverter valve microswitch
  • Fuse
  • Printed Circuit Board (PCB)
Full explanation for PUMP NOT RUNNING