Baxi E168 Fault Code: PCB & Electrical Error Explained
The E168 fault code on Baxi boilers signals that the boiler's control board has detected an internal electrical problem and has shut the unit down as a safety measure. It acts as a broad catch-all alert rather than pinpointing one specific component — the boiler has sensed something is wrong but cannot always identify the precise root cause. On certain models such as the 600 Series and Megaflo range, E168 is linked specifically to a temperature sensor fault, while on Duo-tec models it is more commonly associated with a PCB voltage error or ignition lockout. The boiler will not restart until the underlying fault is resolved and the error is cleared.
General guidance only — not a substitute for professional advice. 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.
What does the Baxi E168 fault code mean?
The E168 fault code on Baxi boilers signals that the boiler's control board has detected an internal electrical problem and has shut the unit down as a safety measure. It acts as a broad catch-all alert rather than pinpointing one specific component — the boiler has sensed something is wrong but cannot always identify the precise root cause. On certain models such as the 600 Series and Megaflo range, E168 is linked specifically to a temperature sensor fault, while on Duo-tec models it is more commonly associated with a PCB voltage error or ignition lockout. The boiler will not restart until the underlying fault is resolved and the error is cleared.
Common causes
- Faulty or failing PCB Common
The PCB (printed circuit board) is the boiler's brain, and E168 often points directly to it. A common cause is an incorrect voltage being fed back through the DC low-voltage side of the board, which can damage internal components over time. Corrosion, moisture ingress, or a simple electrical surge can also cause the board to flag an internal error and lock out.
- Ignition failure or flame not detected Common
The boiler attempts to light the burner several times during each ignition sequence. If the ionisation probe does not confirm a stable flame within the allowed window, the PCB logs a lockout. The problem could lie anywhere along the ignition chain — a worn electrode, a cracked ignition lead, a dirty or faulty flame-sensing probe, or insufficient gas reaching the burner.
- Unstable or out-of-tolerance mains voltage Sometimes
Baxi boilers require a 230V AC supply and will tolerate a deviation of roughly ±10%. If the mains voltage in your property regularly falls above or below this range — even temporarily during peak demand — the PCB can trip and display E168. This cause can be intermittent and is easy to overlook.
- Cascading fault from an earlier error code Sometimes
The boiler may have previously shown a more specific fault code such as E20 (sensor issue) or E119 (low system pressure). If that fault was reset without being properly diagnosed, the boiler can lose track of the original problem and default to displaying E168 on the next lockout attempt.
- Gas supply interruption Sometimes
If the gas supply to the boiler is low, unstable, or completely interrupted — due to a closed isolation valve, a problem at the meter, or a network-side issue — ignition will fail repeatedly and the E168 lockout will follow.
- Wiring faults or loose electrical connections Rare
Loose terminals, chafed wiring, or damage caused by a power surge can disrupt signals between components and the PCB, causing it to log an electrical error. These faults are not always visible without a proper inspection.
How to fix it
- Check whether other gas appliances in your home are working DIY safe
Turn on a gas hob ring or check another gas appliance. If nothing gas-powered is working, the issue may be with your supply. Contact your gas network operator (e.g. Cadent, SGN, or Wales & West Utilities) — do not attempt to work on the meter or pipework yourself.
- Verify your boiler's system pressure is between 1 and 1.5 bar DIY safe
Look at the pressure gauge on the front of the boiler. If it reads below 1 bar, the system may need topping up via the filling loop — consult your boiler's user manual for the correct procedure. Low pressure alone can trigger lockouts, and restoring correct pressure may help clear the fault.
- Attempt a single boiler reset DIY safe
Press and hold the reset button (usually marked with a flame or 'R' symbol) for around three seconds, then release it and allow the boiler up to 60 seconds to complete its ignition sequence. Do this once only. If the boiler fires up and E168 does not return within the next few hours, monitor it carefully. If the fault comes back, do not reset again — repeated resets can mask the underlying problem and cause further damage.
- Have a Gas Safe engineer carry out a full electrical and component inspection Gas Safe engineer
A registered engineer will use diagnostic equipment to check mains voltage stability, inspect the PCB for signs of corrosion or voltage irregularities, test the ignition electrode, lead, and ionisation probe, and check the gas valve operation. Do not open the boiler casing or attempt to test or replace any internal components yourself — this is a legal requirement in the UK and carries serious safety risks.
- Replace faulty components as identified by the engineer Gas Safe engineer
Depending on the diagnosis, the engineer may need to replace one or more parts: the ignition electrode or lead, the flame-sensing probe, a temperature sensor, or in more serious cases the PCB or gas valve. All parts should be genuine Baxi replacements or approved equivalents to ensure compatibility and warranty compliance.
- Request a boiler service if one is overdue Gas Safe engineer
If your boiler has not been serviced within the last 12 months, ask the engineer to carry out a full service at the same visit. A service checks for worn parts, poor connections, and signs of internal problems before they develop into faults like E168 — and keeps your manufacturer warranty valid.
Parts you may need
- Baxi PCB (control board) · from £250
- Ignition electrode · from £30
- Ignition lead · from £20
- Ionisation / flame-sensing probe · from £25
- NTC temperature sensor · from £25
- Gas valve · from £120
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–£350, depending on the underlying cause.
Frequently asked questions
Can I fix the Baxi E168 fault myself?
Your options as a homeowner are limited to checking gas supply, verifying system pressure, and attempting a single reset. Any work inside the boiler casing — including testing or replacing the PCB, ignition components, gas valve, or wiring — must be carried out by a Gas Safe registered engineer. This is a legal requirement in the UK, not just a recommendation.
Why does my Baxi boiler keep showing E168 after I reset it?
If E168 returns shortly after a reset, it usually means the underlying cause has not been resolved. The PCB is detecting a recurring electrical or ignition problem and locking out again as a safety measure. Continuing to reset the boiler can mask the root fault and potentially cause further damage. Stop resetting and call a Gas Safe engineer to carry out a proper diagnosis.
How much does it cost to repair a Baxi E168 fault?
Most E168 repairs in the UK fall between £150 and £350, depending on what the engineer finds. Replacing an ignition electrode or probe typically sits at the lower end of that range, while a full PCB replacement will push costs higher — the PCB part alone can be £200–£300 before labour. If the gas valve also requires replacement, costs can exceed £400. Getting a diagnosis first helps avoid paying for parts that may not be needed.
Is the Baxi E168 fault dangerous?
The boiler itself is not in immediate danger — E168 is a safety lockout, which means the boiler has already shut itself down to prevent a more serious problem. You should not attempt to override the lockout or repeatedly reset the boiler. Leave the boiler off and contact a Gas Safe registered engineer to assess it. If you smell gas at any point, leave the property, avoid switching anything electrical on or off, and call the National Gas Emergency Service on 0800 111 999.