Alpha 0A1 Fault Code: Causes, Fixes & Repair Costs
What does the Alpha 0A1 fault code mean?
The 0A1 fault code on Alpha boilers indicates that the boiler has attempted to light the main burner but failed to achieve or confirm a stable flame. After one or more unsuccessful ignition attempts, the boiler locks out and displays 0A1 to protect the appliance and household. Until the underlying cause is resolved, the boiler will not produce hot water or central heating. Note that Alpha boilers can display fault codes differently depending on the model — newer digital-display models show the numeric code directly, while some older models indicate faults through a sequence of flashing LEDs; consult your model's handbook if you are unsure how to read the display.
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
- Interrupted gas supply Common
If the gas meter cock is partially or fully closed, or if there is a temporary drop in mains gas pressure, the burner will not receive enough fuel to ignite. This is one of the most straightforward causes to rule out before calling an engineer.
- Worn or dirty ignition electrodes Common
The ignition electrodes produce the spark that lights the burner. Over time they accumulate carbon deposits or the tips erode, making it difficult to generate a reliable spark. Electrode degradation is a leading cause of ignition-related service calls on domestic boilers.
- Faulty or contaminated flame sensor (ionisation probe) Common
Once ignition occurs, the flame sensor confirms that a flame is actually present. If the probe is coated in residue or has developed a fault, it may report no flame even when the burner has lit, causing the boiler to shut down and log the 0A1 code.
- Defective ignition lead Sometimes
The high-voltage lead that carries the spark signal from the PCB to the electrode can crack, perish, or develop a poor connection. A damaged lead results in a weak or absent spark even if the electrode itself is in good condition.
- Faulty gas valve Sometimes
The gas valve governs the flow of gas to the burner. If it fails to open correctly — whether due to an electrical fault, a mechanical seizure, or age-related wear — no gas reaches the burner regardless of how good the ignition components are.
- Air supply or flue obstruction Sometimes
Combustion requires a clean air supply. A blocked air intake, a partially obstructed flue, or a bird's nest near the terminal can upset the air-to-gas ratio enough to prevent a stable flame from forming.
- PCB (Printed Circuit Board) failure Rare
The PCB controls and sequences every stage of the ignition process. If it fails to send the correct signals — due to a power surge, moisture ingress, or component ageing — the ignition sequence will not complete successfully, producing a 0A1 lockout.
How to fix it
- Check that your gas supply is working DIY safe
Try lighting a gas hob or another gas appliance. If those are also not working, your gas supply may be interrupted — contact your gas supplier directly. Also check that the isolation valve on your gas meter is fully open (the handle should be in line with the pipe).
- Reset the boiler once or twice DIY safe
On most Alpha models, rotate the front selector dial to the RESET position, hold it there for around 30 seconds, then return it to your desired operating mode. If the boiler fires up and runs normally, monitor it closely over the next few hours. If the 0A1 code returns, do not keep resetting — repeated resets can mask a more serious fault.
- Check the system pressure DIY safe
Look at the pressure gauge on the boiler fascia. For most Alpha boilers the cold-fill pressure should sit between 1 and 1.5 bar. If it reads below 1 bar, top up via the filling loop until pressure reaches approximately 1.2 bar, then re-attempt a reset. If you are unsure how to use the filling loop, refer to your boiler's user guide.
- Inspect the flue terminal for obvious blockages DIY safe
Go outside and visually check the flue outlet. Remove any visible debris such as leaves, cobwebs, or bird nesting material from around the terminal. Do not insert anything into the flue itself.
- Contact a Gas Safe registered engineer for internal diagnosis Gas Safe engineer
If the 0A1 code persists after the checks above, the fault lies inside the boiler. A qualified engineer will remove the casing safely, test the ignition electrodes for wear and spark quality, clean or replace the flame sensor, inspect the ignition lead, and assess the gas valve and PCB. None of these tasks are safe or legal for an unqualified person to carry out.
- Have faulty components replaced by the engineer Gas Safe engineer
Once the engineer has identified the root cause, they will replace whichever component is at fault — typically the ignition electrode, ignition lead, flame sensor, gas valve, or PCB. After the repair, the engineer should run a full functional test and combustion analysis to confirm safe operation.
Parts you may need
- Ignition electrode · from £25
- Ignition lead (HT lead) · from £20
- Flame sensor / ionisation probe · from £20
- Gas valve · from £120
- PCB (printed circuit board) · from £180
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 £100–£320, depending on the underlying cause.
Frequently asked questions
Is it safe to keep resetting my Alpha boiler when the 0A1 code appears?
You can try one or two resets to see if it was a temporary glitch, but that is where it should stop. If the boiler relocks after resetting, continuing to reset it without finding the cause risks masking a genuine fault. At that point you should stop and call a Gas Safe engineer.
How much does it typically cost to fix an Alpha 0A1 fault in the UK?
Most homeowners pay somewhere between £100 and £320 for the repair. Replacing ignition electrodes, the ignition lead, or the flame sensor tends to come in at the lower end of that range (roughly £80–£180 including labour), while a gas valve replacement typically costs £200–£350. A PCB replacement can push costs higher — sometimes £300–£450 or more — but this is a less common outcome. If your boiler is over ten years old and repair quotes are approaching £400, it is worth comparing that against the cost of a new boiler installation.
Will my Alpha warranty cover the 0A1 fault code?
It may do. Alpha boilers typically carry a warranty of between 7 and 10 years depending on the model and registration. If your boiler is still within the warranty period and you have kept up with annual services by a Gas Safe engineer, contact Alpha directly before arranging an independent repair — they should be able to send an approved engineer at no charge for covered faults.
Can an annual service prevent the 0A1 fault from recurring?
Yes, regular servicing significantly reduces the likelihood of ignition faults returning. During a service a Gas Safe engineer will clean the ignition electrodes and flame sensor, check the condition of the ignition lead, and verify that all combustion components are functioning correctly. Catching worn parts early is far cheaper than a breakdown call-out, and many engineers recommend annual servicing as the single most effective way to avoid lockout codes like 0A1.