Remeha E.01.04 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E.01.04 fault code mean?
The E.01.04 code on a Remeha boiler means the appliance has detected multiple unintended flame losses within a 24-hour period. In plain terms, the boiler manages to light but cannot hold a stable flame, and after several failed attempts the safety system steps in and locks the boiler out to prevent unsafe operation. This is a combustion-safety fault — the boiler is telling you that something is preventing it from burning gas reliably, whether that is a problem with the flame-sensing electrode, the gas supply, the flue, or the gas valve itself. Because this fault sits within the E.01 ignition and flame family, you may also see related codes such as E.01.01 (no ignition spark), E.01.02 (spark present but no flame established), or E.01.03 (flame detected but ionisation signal too weak) on other Remeha models — E.01.04 specifically indicates the flame has been lost repeatedly during normal running, rather than at the point of first ignition.
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
- Dirty or worn ionisation (flame-sensing) electrode Common
The ionisation electrode measures a tiny electrical current that flows through the flame to confirm combustion is happening. If the electrode tip is coated in carbon deposits or has worn down over time, it sends a weak or absent signal even when the flame is present, causing the boiler to conclude the flame has gone out and shut off the gas. This is the single most common root cause of E.01.04 and is usually found during a service visit.
- Gas supply interruption or low gas pressure Common
If the mains gas pressure at the meter drops — due to a supply issue from your network operator, a partially closed isolation valve, or high demand across the street — the burner cannot maintain a stable flame and it extinguishes. Checking whether your gas hob or other gas appliances are working normally is a quick first indicator of whether this is the cause.
- Flue gas recirculation or flue blockage Sometimes
If exhaust gases from the flue outlet are being drawn back into the air inlet — perhaps because the terminal is partially obstructed, positioned in a poorly ventilated area, or the flue has a partial blockage — the boiler draws in CO₂-rich air that disrupts combustion and snuffs out the flame. This can be a particularly frustrating cause because it may only happen under certain wind conditions.
- Faulty or incorrectly calibrated gas valve Sometimes
The gas valve controls the flow of gas to the burner. If it is sticking, leaking internally, or delivering gas at the wrong rate, the air-to-gas ratio at the burner becomes unstable and the flame flickers out. On some Remeha models (notably the Tzerra Ace), a misconfigured combustion parameter such as GP008 can mimic a gas valve fault by causing the mixture to be too lean or too rich.
- Frozen or blocked condensate pipe Sometimes
In cold weather, the condensate pipe that drains acidic water away from the boiler can freeze solid. When the resulting blockage triggers a condensate fault, it can cascade into ignition and flame-loss codes including E.01.04. This cause is seasonal and almost exclusively seen in sustained freezing temperatures.
- PCB (printed circuit board) fault Rare
The PCB interprets the ionisation signal and controls the gas valve and ignition sequence. If the board itself is misreading signals or producing intermittent faults in the control circuitry, the boiler may falsely conclude the flame has been lost. This is typically a diagnosis of exclusion — an engineer will check electrodes, gas supply, and the flue before pointing to the PCB.
How to fix it
- Check that 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 works, the problem is likely with your mains gas supply rather than the boiler. Contact your gas supplier or call the National Gas Emergency line on 0800 111 999 if you suspect a supply failure or smell gas.
- Check the boiler's system pressure DIY safe
Look at the pressure gauge on the boiler's front panel. It should read between 1.0 and 1.5 bar when the system is cold. If it is below 1 bar, top it up carefully using the filling loop (usually a braided flexible hose beneath the boiler) until it reaches 1.2 bar, then close the filling loop valves. Consult your boiler's user guide if you are unsure how to do this.
- Check the condensate pipe for freezing (winter only) DIY safe
If the outside temperature is at or below zero, go outside and check the condensate pipe — usually a white plastic pipe exiting through an external wall near the boiler and running to a drain. If it feels solid or you can see ice, you can thaw it gently using warm (not boiling) water poured over it or a heat pad. Never use a naked flame. Once thawed, reset the boiler as described in the next step.
- Reset the boiler once DIY safe
Press and hold the reset button on the front panel for approximately three seconds (refer to your user guide for your specific model). Wait at least 60 seconds to see whether the boiler fires and stays running. If it locks out again with the same code, do not continue resetting — repeated resets without fixing the underlying cause will not help and may mask useful diagnostic information for your engineer.
- Arrange for a Gas Safe registered engineer to inspect the ionisation and ignition electrodes Gas Safe engineer
An engineer will access the combustion chamber, visually inspect the electrode tips for carbon fouling or physical wear, and measure the ionisation current using appropriate test equipment. If the current is below specification, the electrodes will be cleaned (sometimes with fine abrasive paper) or replaced. This is the most common fix for E.01.04 and is often carried out as part of a standard annual service.
- Have the engineer check the gas valve and inlet pressure Gas Safe engineer
The engineer will verify that the gas pressure at the boiler inlet is within Remeha's specified range and that the gas valve is opening and closing correctly. If the valve is sticking or delivering inconsistent flow, it will need replacing. On applicable models, the engineer should also check combustion parameters (such as GP008 on the Tzerra Ace) and reset them to the manufacturer's recommended values if they have drifted.
- Have the engineer inspect the flue system for recirculation or blockage Gas Safe engineer
The engineer will check the entire flue run for obstructions, damage, or incorrect terminal positioning that could allow exhaust gases to recirculate into the air intake. They will also check all flue joints are properly sealed. If recirculation is identified, a flue deflector or repositioning of the terminal may be required.
- Have the engineer test the PCB if the fault persists Gas Safe engineer
If all mechanical components check out — electrodes, gas valve, flue, and condensate system — the engineer will test the PCB's output signals and ionisation circuit. A faulty board will need replacing; given the cost, a reputable engineer should confirm this diagnosis clearly before ordering parts. If the fault is recurring and difficult to reproduce, it is worth asking your engineer to contact Remeha's technical support line for further guidance.
Parts you may need
- Ionisation / flame-sensing electrode · from £35
- Ignition electrode · from £30
- Gas valve (Remeha compatible) · from £120
- Condensate trap / siphon · from £25
- 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 £100–£350, depending on the underlying cause.
Frequently asked questions
Can I keep resetting the boiler to clear E.01.04?
You can try a single reset to see if the fault clears, but if the boiler locks out again with the same code you should stop resetting and call an engineer. Repeated resets do not cure the underlying fault — they just restart the ignition sequence — and in the worst case they can delay a proper diagnosis. E.01.04 specifically indicates the flame has been lost multiple times already, so the boiler's own safety logic has decided the situation is not resolving itself.
How much does it typically cost to fix E.01.04 on a Remeha boiler?
For the most common cause — a dirty or worn ionisation electrode — you are usually looking at £100 to £175 all-in once you include the engineer's call-out, their time, and any parts. A gas valve replacement typically brings the bill to around £200–£350. These are the repairs most people with this fault end up paying for. A PCB replacement is less common and can cost £300–£450 or more depending on the model; if your boiler is over ten years old and needs a PCB, it is worth getting a replacement quote alongside the repair quote.
Why does my Remeha Tzerra Ace keep showing E.01.04 even after the engineer replaced the electrode?
On the Tzerra Ace in particular, there are documented cases where a misconfigured combustion parameter (referenced as GP008 in Remeha's installer settings) causes an incorrect air-to-gas mixture that extinguishes the flame during running. If electrode replacement has not solved the problem, ask your engineer to check the combustion parameters against Remeha's specification and, if needed, contact Remeha's own technical support team for guidance on resetting the parameter correctly. Flue recirculation is another cause worth investigating if the fault is intermittent and weather-dependent.
Is E.01.04 dangerous — do I need to leave the house?
The boiler has locked itself out as a safety precaution, which means gas is not being burned and there is no immediate danger from the boiler itself. You do not need to evacuate. However, if you smell gas at any point, do not attempt to reset the boiler — leave the property, avoid using light switches, and call the National Gas Emergency Service on 0800 111 999 immediately. Once the boiler is in lockout and you cannot smell gas, it is safe to stay home while you arrange for an engineer to visit.