Ravenheat CSI01 Fault Code: Causes, Fixes & Repair Costs
What does the Ravenheat CSI01 fault code mean?
Fault code 01 on the Ravenheat CSI 120 range means the boiler has failed to ignite: the control board ran its ignition sequence — fan proving, spark, gas valve — and never confirmed a flame, so it shut the attempt down and locked out. Ravenheat's fault-finding for this code points at the gas valve operation, the fan failing to start, and the ignition control board and its cables. In real installations the same short list accounts for nearly every case, alongside the perennial first check: whether gas is actually reaching the boiler at all (a closed valve, an interrupted supply or, in winter, a frozen condensate pipe blocking ignition on condensing models).
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
- No or restricted gas supply Common
A closed isolation valve, supply interruption or very low inlet pressure means the spark has nothing to light. Checking other gas appliances in the property is the quickest homeowner-safe way to rule this in or out.
- Gas valve not operating Common
If the valve fails to open (electrically or mechanically), no gas reaches the burner during the ignition window and the attempt fails. Ravenheat lists the valve first for this code; engineers test its coils and operation directly.
- Fan failing to start or prove Common
The board will not release gas until the fan runs and proves airflow. A seized or dead fan, or a failed proving signal, aborts ignition before a spark is ever attempted.
- Ignition board or cables faulty Sometimes
A weak spark from a failing ignition control board, degraded HT leads or a worn electrode leaves gas unlit during the window, causing a lockout on code 01.
How to fix it
- Check other gas appliances DIY safe
If a gas hob or fire will not light either, the problem is the supply, not the boiler — check your emergency control valve is open and contact your supplier if gas is off.
- In freezing weather, check the condensate pipe DIY safe
A frozen external condensate pipe stops ignition on condensing models. If the white plastic pipe outside is frozen, thaw it gently with warm (never boiling) water and reset.
- Reset the boiler once or twice at most DIY safe
Reset and watch the sequence: fan note, spark clicks, then either a flame or a return to lockout. If code 01 returns twice, stop — repeated attempts on a genuine ignition fault achieve nothing.
- Have an engineer test the valve, fan and ignition circuit Gas Safe engineer
A Gas Safe registered engineer will confirm inlet gas pressure, test the gas valve, verify the fan runs and proves, and check the ignition board, leads and electrode. All of this is sealed-case and gas-carrying work — never DIY.
Parts you may need
- Ignition electrode and lead · from £30
- Fan assembly · from £110
- Gas valve · from £130
- Ignition/control board · 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 £120–£350, depending on the underlying cause.
Frequently asked questions
What does fault 01 mean on a Ravenheat CSI 120?
Ignition failure — the boiler tried to light and never confirmed a flame, so it locked out. Ravenheat's own list for this code is the gas valve, the fan failing to start, and the ignition board and cables; before any of that, check gas is actually reaching the property and, in winter, that the condensate pipe is not frozen.
How many times can I reset a code 01 lockout?
Try once, at most twice. Each reset repeats a full ignition attempt; if the underlying valve, fan or ignition fault remains, further resets just release small amounts of unburnt gas through failed attempts. If it will not hold a flame after two tries, call a Gas Safe registered engineer.
Could this just be my gas supply?
Yes — it is the first thing to rule out. If other gas appliances are dead too, the issue is upstream of the boiler: check your emergency control valve and your supplier. If everything else works, the fault is in the boiler's ignition chain.