Ravenheat CSI 85 Fault codes & diagnostics

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

Combi Natural Gas 24.9 kW 1998 onwards Discontinued
GC Numbers 47-581-1947-581-2047-581-2347-581-24
Download the Ravenheat CSI 85 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 →

Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-581-19 CSI 85 1998–present
47-581-20 CSI 85T 1998–present
47-581-23 CSI 85 LPG 1998–present
47-581-24 CSI 85T LPG 1998–present
Just want the most common Ravenheat CSI 85 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 3 documented codes

Tap any card for details

E02

Your boiler has stopped working because water is not moving through the system properly, which is causing it to overheat and shut down for safety.

High DIY-safe £180-350

What to check first

  1. Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge
  2. Ensure all radiator valves and isolation valves under the boiler are fully open
  3. Bleed your radiators to remove any trapped air that might be blocking circulation
  4. Press the reset button to see if the boiler restarts

Parts commonly replaced

  • Circulating pump
  • Automatic air vent
  • Main heat exchanger (de-scaling)

Related codes

Full explanation for E02
E23

Your boiler has detected a fault with the sensor that monitors exhaust gases, and as a safety precaution, it will not operate until this is fixed.

High Engineer only £120-£210

Parts commonly replaced

  • Flue Gas NTC Sensor
  • Connecting Wiring Harness

Related codes

Full explanation for E23
E24

Your boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, preventing the system from operating correctly.

High Engineer only £90-160

Parts commonly replaced

  • Central heating return NTC sensor
  • Wiring harness
  • Main circuit board (PCB)

Related codes

Full explanation for E24
Status & diagnostic codes

4 operating states & engineer diagnostics

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

C12 Diagnostic Your boiler is struggling to detect or manage its air supply and exhaust system, meaning it has shut down to keep you safe. C32 Diagnostic Your boiler is struggling to detect or properly manage the exhaust gases being vented outside, which prevents it from starting safely. C52 Diagnostic Your boiler has detected an issue with the way it is venting exhaust gases, meaning it cannot operate safely. F1 Diagnostic Your boiler is struggling to correctly manage the flow of air and gas needed for combustion, which prevents it from firing up safely.