Baxi E.02-.00 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E.02-.00 fault code mean?
The E.02-.00 code (also displayed as E02-00 or E02 – .00 on some Baxi models) indicates that your boiler has shut itself down as a safety measure and is awaiting a reset. Rather than pointing to one specific component failure, it signals that the boiler's internal safety system has been triggered — meaning something caused the unit to lock out before it could complete a normal heating or hot water cycle. The most frequent triggers are low system pressure, a frozen condensate pipe, an ignition failure, or a fan/flue problem. The boiler will remain inactive until the underlying issue is identified and resolved, and a proper reset is performed.
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.
Common causes
- Low System Water Pressure Common
The most common trigger for this lockout. Baxi boilers typically require a system pressure of 1.0–1.5 bar when cold. Pressure can drop gradually due to small leaks, a faulty pressure relief valve (PRV), or after bleeding radiators without topping the system back up. When pressure falls below the minimum threshold, the boiler shuts down to protect itself.
- Frozen Condensate Pipe Common
During cold snaps, the plastic condensate pipe that runs outside the property can freeze solid, blocking the discharge of acidic condensate water. The boiler detects this blockage and locks out. This is especially common on pipes that run along an exposed external wall or are inadequately insulated.
- Ignition or Gas Supply Failure Common
If the boiler attempts to light and fails — either because the gas supply is interrupted, the ignition electrode is worn or fouled, or the gas valve is not opening correctly — it will lock out after a set number of unsuccessful ignition attempts. Checking whether other gas appliances in the home are working is a useful first diagnostic step.
- Faulty Fan or Flue Obstruction Sometimes
The boiler's fan must reach the correct speed and prove adequate airflow before ignition is permitted. A failing fan motor, a damaged wiring harness, or a blockage in the flue (such as debris, a bird's nest, or a damaged terminal) can all prevent this, causing a safety lockout.
- Sludge Buildup or Poor Circulation Sometimes
In systems that have never been power-flushed or that lack an inhibitor, iron oxide sludge can accumulate and restrict water flow through the heat exchanger. This leads to overheating and repeated lockouts. If E.02-.00 keeps returning without an obvious cause, circulation issues are worth investigating.
- PCB or Electrical Fault Rare
The printed circuit board (PCB) controls every function of the boiler. If it develops a fault — due to age, a power surge, or moisture ingress — it can incorrectly trigger a lockout or fail to clear a previous one. This is a less common cause but should be considered if all other checks draw a blank.
How to fix it
- Check the system pressure gauge DIY safe
Look at the pressure gauge on your boiler's fascia. It should read between 1.0 and 1.5 bar when the heating is cold. If it reads below 1.0 bar, the system needs repressurising. Locate the filling loop (usually a braided silver hose beneath the boiler) and slowly open the valve(s) until the gauge rises to around 1.2 bar, then close the valve firmly. Never overfill beyond 2.0 bar.
- Check whether other gas appliances are working DIY safe
Turn on a gas hob ring or gas fire if you have one. If these also have no gas, the issue is with the gas supply to your property rather than the boiler itself. In that case, contact your gas network operator (e.g. Cadent, Northern Gas Networks) rather than a boiler engineer.
- Inspect and thaw a frozen condensate pipe if applicable DIY safe
If temperatures have recently dropped below freezing, locate the white plastic condensate pipe where it exits the property. If it feels solid or you can see ice, pour warm (not boiling) water over the frozen section or wrap it with a warm damp cloth until it clears. Once thawed, insulate the pipe with foam lagging to reduce the risk of it refreezing.
- Reset the boiler once DIY safe
Press and hold the reset button (usually marked with a flame symbol or the letter R) for around 3 seconds, then release. Allow the boiler a full minute to attempt ignition. If it fires up and runs normally, monitor it over the next day or two. Do not reset the boiler more than two or three times in total — repeated lockouts without resolution indicate an underlying fault that requires professional diagnosis.
- Have a Gas Safe engineer carry out a full diagnostic Gas Safe engineer
If the boiler locks out again after resetting, or if you cannot identify the cause yourself, a Gas Safe registered engineer should be called. They will be able to test the ignition system, fan, gas valve, and sensors with proper tools, and can safely inspect internal components such as the heat exchanger and PCB. Do not attempt to open the boiler casing or interfere with gas components yourself.
Parts you may need
- Pressure Relief Valve (PRV) · from £35
- Expansion Vessel · from £55
- Ignition Electrode · from £25
- Fan Assembly · from £120
- Diverter Valve · from £65
- PCB (Printed Circuit Board) · from £220
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
Can I just keep resetting my Baxi boiler to clear E.02-.00?
Resetting once or twice is perfectly reasonable — sometimes a one-off interruption to the gas supply or a brief pressure dip is all that caused the lockout, and a single reset clears it for good. However, if the code returns within a short period, repeated resets are not the answer. They will not fix an underlying fault and may mask a developing problem. If the boiler locks out more than a couple of times in quick succession, call a Gas Safe registered engineer for a proper diagnosis.
How much does it cost to fix Baxi E.02-.00 in the UK?
For the majority of homeowners, the repair falls somewhere between £120 and £350 once you factor in a call-out, diagnosis, and the most commonly needed parts such as a pressure relief valve, expansion vessel, or ignition electrode. If the fault turns out to be a fan motor, expect to be closer to the upper end of that range. A PCB replacement is a less common outcome but can push costs to £400–£550 or more — if your boiler is over 10–12 years old and needs a PCB, it is worth getting a new boiler quote at the same time to compare.
Why does my Baxi boiler keep losing pressure and triggering E.02-.00?
Occasional minor pressure drops are normal — for example, after bleeding radiators. But if your boiler regularly loses pressure without an obvious reason, there is likely a slow leak somewhere in the system. Common culprits include a weeping pressure relief valve (which may be discharging to the outside drain), a failing expansion vessel that can no longer hold its charge, or a small leak on a radiator valve or pipework joint. A Gas Safe engineer can pressure-test the system and identify the source.
Is E.02-.00 dangerous?
The lockout itself is a safety feature, not a hazard — it means the boiler has done exactly what it should and shut down rather than continuing to operate unsafely. However, you should not ignore it or try to bypass it. The underlying cause (such as a gas ignition failure or a faulty component) may become more serious if left unaddressed. Always resolve the root cause before returning the boiler to normal use.