Biasi ER69 Fault Code: Causes, Fixes & Repair Costs
What does the Biasi ER69 fault code mean?
The ER69 code appears on Biasi boilers when the control system detects an electrical or wiring fault serious enough to trigger a safety lockout. The boiler shuts itself down completely, meaning you'll have no central heating and no hot water until the underlying problem is identified and resolved. Because the fault points directly at internal wiring or electronic components, this is not something a homeowner should attempt to fix — a Gas Safe registered engineer must diagnose and repair 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
- Loose or damaged wiring connections Common
Vibration over time, heat cycles, or poor previous repair work can cause wiring terminals inside the boiler to work loose or corrode. A loose connection in the wrong place is enough to trip the electrical fault detection and throw an ER69. This is the most frequently found culprit when an engineer opens the casing.
- Faulty diverter valve Common
The diverter valve controls whether hot water from the heat exchanger is directed to your radiators or your taps. If its internal mechanism or wiring harness develops a fault, the boiler's electronics can register this as an electrical error and lock out with ER69. You may notice that hot water or heating was working intermittently just before the lockout.
- PCB (printed circuit board) fault Sometimes
The PCB is the boiler's main control board. If a component on the board fails or a solder joint cracks — often due to age or heat stress — it can cause erratic signals that the boiler interprets as an electrical fault. PCB faults sometimes produce intermittent ER69 codes that disappear after a reset before returning.
- Faulty gas valve wiring or solenoid Sometimes
The gas valve has its own wiring loom and solenoid coils. If these develop a fault, the boiler's control system may detect an unexpected electrical reading and lock out. Associated symptoms can include ignition attempts with no burner flame, or banging noises suggesting inconsistent gas delivery before lockout.
- Intermittent internal component failure Rare
Ageing sensors, capacitors, or other electronic components can begin to fail gradually, producing faults that come and go. If your ER69 clears with a reset but returns repeatedly within hours or days, an intermittent component failure is a strong possibility.
How to fix it
- Note the exact fault code displayed DIY safe
Before doing anything else, write down 'ER69' and the time it appeared. If your boiler shows any secondary digits or alternating codes alongside ER69, note those too — they give the engineer useful diagnostic information.
- Try a single boiler reset DIY safe
Press and hold the reset button for 3–5 seconds as described in your Biasi manual. If the boiler fires up successfully, monitor it closely. If ER69 returns within a short time, do not keep resetting — repeated resets on an electrical fault can cause further damage to the PCB or wiring.
- Check that your gas supply is working DIY safe
Confirm that other gas appliances in your home (hob, gas fire) are working normally. If they are not, contact your gas supplier rather than the boiler engineer. If the gas supply is fine, the fault is internal to the boiler.
- Do not attempt to access internal wiring or components Gas Safe engineer
The casing of the boiler must not be removed by anyone other than a qualified engineer. Interfering with wiring, the PCB, the gas valve, or the diverter valve without Gas Safe registration is dangerous and will invalidate any remaining warranty.
- Call a Gas Safe registered engineer to diagnose the fault Gas Safe engineer
An engineer will remove the casing, inspect the wiring harness for loose terminals, chafing, or burn marks, and use diagnostic equipment to test the PCB, diverter valve, and gas valve solenoids. Once the faulty component is identified, they will repair or replace it and carry out safety checks before handing the boiler back to you.
- Check your Biasi warranty before authorising repairs DIY safe
Biasi boilers typically carry a 2–7 year warranty depending on the model and registration. If your boiler is still within the warranty period, contact Biasi directly before agreeing to any paid repairs, as the work may be covered at no cost to you.
Parts you may need
- Diverter valve assembly · from £85
- Gas valve · from £220
- PCB (main control board) · from £180
- Wiring loom / harness · from £65
- Ignition lead and electrode set · from £35
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 £150–£400, depending on the underlying cause.
Frequently asked questions
Can I keep resetting my Biasi boiler to clear the ER69 code?
You can try one reset to see if the fault clears, but avoid repeated resets if ER69 keeps coming back. Continuously resetting a boiler with an underlying electrical fault risks further damage to the PCB or wiring, and could make an eventual repair more expensive. If the code returns after a single reset, switch the boiler off and call an engineer.
Is ER69 always a major repair, or could it be something simple?
It genuinely varies. Sometimes the fix is as straightforward as an engineer re-seating a loose wiring terminal, which can cost as little as a standard call-out charge of around £80–£120. More involved repairs — like a diverter valve or gas valve replacement — typically fall in the £200–£400 range including labour. A full PCB replacement is at the higher end and can occasionally exceed £500 on older models, which is worth considering against the boiler's age and remaining life.
My Biasi boiler is several years old and showing ER69 — is it worth repairing?
As a rough guide, if the repair quote is under £500 and your boiler still has warranty remaining, a repair usually makes financial sense. If the boiler is over 10 years old, has had several faults, and the repair cost approaches or exceeds £500, it is worth getting a new boiler quote to compare — modern condensing boilers are significantly more efficient and could cut your energy bills enough to offset the replacement cost over a few years.
Do I need a Gas Safe engineer for an electrical fault, or just an electrician?
You need a Gas Safe registered engineer, not a general electrician. Although ER69 is triggered by an electrical fault, all of the wiring and components involved are inside a gas appliance. Only a Gas Safe registered engineer is qualified and legally permitted to work inside a gas boiler in the UK. An electrician working on internal boiler components would be working outside their competence and potentially breaking the law.