Ravenheat CSI17 Fault Code: Causes, Fixes & Repair Costs
What does the Ravenheat CSI17 fault code mean?
Fault code 17 on the Ravenheat CSI 120 range points to a problem with the fan's electrical supply — Ravenheat describes it as a possible issue with fan voltage. The fan is safety-critical: it clears the combustion chamber and proves airflow before the board will release gas, and its speed is driven and monitored electrically. If the voltage reaching the fan is wrong — through a failing board output, degraded wiring or a fan winding drawing incorrectly — the proving chain fails and the boiler stops rather than fire with unverified airflow. The practical suspects are the fan itself, its supply leads and connectors, and the control board output that drives it.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Fan motor winding degrading Common
As the fan motor ages, its windings can draw abnormal current and pull the supply voltage out of specification, tripping the monitoring. Often preceded by a noisy or slow-starting fan.
- Wiring or connector faults in the fan supply Common
Heat-hardened insulation, loose spade terminals or corroded connectors add resistance and drop the voltage at the fan. The fault can be intermittent, appearing as things warm and expand.
- Control board fan output failing Sometimes
The PCB circuit that drives and monitors the fan can degrade, delivering incorrect voltage even to a healthy fan. Confirmed by measuring at the board with the fan disconnected.
- Mains supply issues Rare
Genuine under-voltage at the property — or a failing fused spur — can occasionally present as a fan-voltage fault. Engineers verify incoming supply as part of the diagnosis.
How to fix it
- Listen at start-up DIY safe
When the boiler attempts to fire, note whether the fan spins up at all, sounds laboured, or rattles. This observation alone helps the engineer split a dying fan from a supply problem.
- Reset once DIY safe
Try a single reset. If code 17 returns immediately or as soon as the fan is asked to run, leave it locked out and book service — the fan chain is not something to keep forcing.
- Do not open the case to check the fan Gas Safe engineer
The fan and its supply run at mains voltage inside the sealed combustion-side casing. All measurement and replacement work is for a Gas Safe registered engineer.
- Engineer: measure the fan supply and test the fan Gas Safe engineer
The engineer will measure voltage at the fan under demand, inspect the loom and connectors, test the fan's windings, and check the PCB output. Replacement of the failed element — fan, loom or board — follows, with a full combustion check afterwards.
Parts you may need
- Fan assembly · from £110
- Fan wiring loom/connectors · from £25
- Control PCB · from £170
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £130–£350, depending on the underlying cause.
Frequently asked questions
What does fault 17 mean on a Ravenheat CSI 120?
The boiler has detected a problem with the fan's electrical supply — the voltage driving the fan is not what the board expects. Because the fan proves the airflow that makes ignition safe, the boiler locks out rather than fire. The usual culprits are the fan motor itself, its wiring, or the board output driving it.
The fan sounds noisy before the fault appears — related?
Very likely. A rumbling, screeching or slow-starting fan is a motor on its way out, and a failing motor commonly drags the supply voltage out of specification — exactly what code 17 reports. Mention the noise when you book the engineer.
Is this a DIY fix?
No. The fan is part of the combustion air chain inside the sealed case and runs at mains voltage. Diagnosis and replacement are legally and practically a Gas Safe registered engineer's work.