Chaffoteaux Sterling FF Fault codes & diagnostics

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

Combi Natural Gas 15-24 kW 1997-2005 Discontinued
GC Number 47-980-04

Replaced by: Chaffoteaux Britony

Download the Chaffoteaux Sterling FF manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
13 High 3 Medium
Just want the most common Chaffoteaux Sterling FF faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 16 documented codes

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2a

Your boiler has stopped working because the amount of water inside the heating system has dropped too low.

High DIY-safe £0-80

What to check first

  1. Locate the external filling loop, which is a silver braided hose usually found underneath the boiler.
  2. Open the small valve(s) on the loop to let water in until the pressure gauge on the front of the boiler reads between 1 and 1.5 bar.
  3. Close the valve(s) tightly once the correct pressure is reached.

Parts commonly replaced

  • Pressure gauge
  • Filling loop
  • Pressure relief valve

Related codes

Full explanation for 2a
2b

Your boiler is making loud noises because the internal water pump is failing to move water around the system properly.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Pump head
  • Pump capacitor
Full explanation for 2b
5.i

Your boiler is struggling to detect the flow of water correctly, meaning it is failing to heat your taps or shower effectively.

High Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water flow switch
  • Water governor assembly

Related codes

Full explanation for 5.i
5.iv

Your boiler is struggling to heat your water properly because an internal component inside the flue system is not the correct size for your specific appliance.

High Engineer only £150-250

Parts commonly replaced

  • Venturi

Related codes

Full explanation for 5.iv
5.vi

Your boiler is failing to switch on the internal valves required to provide hot water to your taps.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve
  • PCB
  • Wiring harness
Full explanation for 5.vi
5.viii

Your boiler is struggling to work because it is not receiving enough gas from your supply mains.

High Engineer only £100-250

Parts commonly replaced

  • Gas valve
  • Gas meter regulator
  • Gas pipework isolation

Related codes

Full explanation for 5.viii
6.iv

Your boiler is failing to detect the water flow needed to start heating your home or providing hot water.

High Engineer only £120-220

Parts commonly replaced

  • Flow switch
  • DHW diaphragm
Full explanation for 6.iv
7.iii

Your boiler has lost the air pressure needed to run smoothly, causing it to release excess water to prevent unsafe pressure levels within the system.

High Engineer only £150-250

Parts commonly replaced

  • Expansion vessel
  • Pressure relief valve
Full explanation for 7.iii
10

Your boiler is struggling to maintain a steady temperature and is repeatedly turning its internal burner on and off to compensate.

Medium Engineer only £120-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Central Heating Pump
  • Primary Heat Exchanger

Related codes

Full explanation for 10
10.i

Your boiler is struggling because it cannot pump enough water through the system, causing it to rapidly turn on and off to protect itself.

Medium DIY-safe £120-250

What to check first

  1. Check your central heating pressure gauge and top it up to 1.5 bar if low
  2. Ensure all radiator valves are fully open
  3. Check that your external pump speed setting has not been turned down

Parts commonly replaced

  • Circulating pump
  • Flow switch
  • Diverter valve

Related codes

Full explanation for 10.i
10.iii

Your boiler is struggling to maintain a steady temperature, causing it to rapidly turn its burner on and off rather than running smoothly.

Medium Engineer only £120-250

Parts commonly replaced

  • System bypass valve
  • Central heating pump
  • Flow sensor

Related codes

Full explanation for 10.iii
10.iv

Your boiler is struggling to move heat away from its internal workings, causing it to quickly turn on and off as it tries to protect itself from overheating.

High Engineer only £150-300

Parts commonly replaced

  • Primary heat exchanger
  • Pump
  • System filter

Related codes

Full explanation for 10.iv
12

Your boiler has stopped working because the water pressure inside your heating system has dropped too low.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (usually a silver braided hose with one or two valves) underneath the boiler.
  2. Open the valve(s) slowly to allow water into the system while watching the pressure gauge.
  3. Close the valve(s) tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel

Related codes

Full explanation for 12
13

Your boiler pressure is rising too high because water is leaking into the system when it shouldn't be, which could cause a leak or pipe burst.

High Engineer only £120-250

Parts commonly replaced

  • Filling loop
  • Plate heat exchanger

Related codes

Full explanation for 13
Lock out radiator light

Your boiler has failed to light the gas flame and has safely shut itself down to prevent any risk.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
Full explanation for Lock out radiator light
Red

Your boiler has detected a fault and stopped working for safety reasons, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed circuit board
  • Flame sensor
Full explanation for Red
Status & diagnostic codes

3 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

204 Diagnostic Your boiler has detected an issue with the sensors that monitor the internal water flow or temperature, meaning it has shut down to protect itself from potential overheating. Green Status There is no fault with your boiler; the green light simply confirms that it is powered on and operating normally. Yellow Status Your boiler is operating normally and is currently running as expected.