Remeha E13 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E13 fault code mean?
The E13 code appears on Remeha boilers — most commonly the Avanta and Avanta Plus range — when the heat exchanger's built-in thermal fuse has responded to a serious overheat condition. This is the boiler's last line of defence against catastrophic overheating: once the thermal fuse trips, it cannot be reset, meaning the heat exchanger itself is permanently damaged and will need to be replaced. On Avanta Plus combi models, E13 can sometimes relate instead to the domestic hot water (DHW) flow switch or the plate heat exchanger specifically, which may present as a loss of hot water while central heating continues to work. A small number of sources also link E13 on certain model variants to an external sensor or weather compensation fault, so it is worth cross-referencing with your specific model's manual. In any case, E13 is a serious fault requiring a Gas Safe registered engineer — this is not a code you can clear with a simple reset.
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
- Thermal fuse blown due to overheating Common
The most serious and most common presentation of E13. The heat exchanger has reached a dangerously high temperature — often caused by restricted water flow, a seized pump, or a pre-existing fault — and the thermal fuse has responded permanently. Once triggered, the heat exchanger cannot be repaired and must be replaced. Importantly, simply fitting a new heat exchanger without finding and fixing the root cause risks destroying the replacement unit too.
- Circulation pump failure Common
A seized or failing pump stops water moving through the heat exchanger at the required rate. Without adequate flow, heat builds up rapidly in the heat exchanger until the thermal fuse activates. A Gas Safe engineer will check whether the pump is running and whether it has become air-locked or mechanically seized.
- Low system pressure or air in the system Sometimes
Low water pressure (below around 1 bar) or a significant air pocket in the system can starve the heat exchanger of flow, contributing to overheating. A homeowner can safely check the pressure gauge and top up via the filling loop if pressure has dropped below 1 bar, but this alone is unlikely to resolve E13 once the thermal fuse has blown.
- Scaled or blocked plate heat exchanger (combi models) Sometimes
On Avanta Plus combi models, limescale or debris can restrict flow through the DHW plate heat exchanger. This can trigger E13 via reduced flow rates, and may present as hot water loss rather than a full heating shutdown. Descaling or replacement of the plate heat exchanger by an engineer may resolve this variant of the fault.
- DHW flow switch fault (combi models) Rare
On some Avanta Plus combi variants, E13 can point to a faulty domestic hot water flow switch — the component that tells the boiler a tap has been opened. If this switch fails or sticks, the boiler may misread demand and generate the E13 code. This is a less common presentation but worth investigating on combi models where heating remains functional.
- External sensor or weather compensation fault Rare
On certain Remeha model variants, E13 has been associated with a problem on an external temperature sensor or weather compensation circuit. If your installation includes weather compensation controls, an engineer should check these connections and sensor readings as part of their diagnosis.
How to fix it
- Check the system pressure gauge DIY safe
Look at the pressure gauge on the front of the boiler. It should read between 1 and 1.5 bar when the system is cold. If it is below 1 bar, use the filling loop to top it up to around 1.2 bar. This will not reset E13 if the thermal fuse has already blown, but it rules out pressure as a contributing factor and is useful information for the engineer.
- Do not attempt to reset the boiler repeatedly DIY safe
Unlike some fault codes, E13 caused by a triggered thermal fuse cannot be cleared by resetting the boiler. Pressing reset once to confirm the lockout is reasonable, but do not keep trying — the boiler has shut down for a safety reason and forcing restarts will not help and could be unsafe.
- Do not attempt to bypass or replace the thermal fuse yourself Gas Safe engineer
The thermal fuse is a critical safety component. Bypassing it — even temporarily — is dangerous and could result in fire. This is work for a Gas Safe registered engineer only. Tampering with a safety device can also create serious legal liability if an incident occurs.
- Have a Gas Safe engineer carry out a full diagnosis Gas Safe engineer
An engineer will check system pressure, pump operation, airlock in the pump, flow rates through the heat exchanger, and the condition of the thermal fuse and heat exchanger itself. On combi models they will also inspect the DHW plate heat exchanger and flow switch. It is essential to identify the root cause before any parts are replaced, otherwise a new heat exchanger may fail in the same way.
- Allow the engineer to address the root cause first Gas Safe engineer
Whether the underlying problem is a failed pump, an airlock, limescale in the plate heat exchanger, or a faulty sensor, this must be resolved before — or alongside — any heat exchanger replacement. An engineer may also descale or replace the DHW plate heat exchanger on combi models if that is the source of the fault.
- Arrange heat exchanger replacement or consider a new boiler Gas Safe engineer
If the primary heat exchanger's thermal fuse has blown, the unit is beyond repair and must be replaced. Given the cost of a new heat exchanger plus labour, if your boiler is more than ten years old it may be more economical to replace the boiler entirely. Ask your engineer to give you a frank comparison of repair versus replacement costs. Note that Remeha offers a five-year warranty on heat exchangers, so check whether your unit is still within that period before agreeing to any paid repair.
Parts you may need
- Primary heat exchanger (Remeha Avanta) · from £275
- DHW plate heat exchanger (Avanta Plus combi) · from £35
- Circulation pump · from £85
- DHW flow switch · from £25
- External temperature sensor · from £20
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 £300–£750, depending on the underlying cause.
Frequently asked questions
Can the Remeha E13 fault be reset or cleared myself?
Unfortunately not, if the thermal fuse on the primary heat exchanger has blown. Unlike a standard lockout, this fuse is a one-shot safety device — once it has triggered, it signals that the heat exchanger has suffered irreparable damage from overheating. No amount of resetting the boiler will clear it. You will need a Gas Safe registered engineer to diagnose the fault and arrange replacement of the heat exchanger. On combi models where E13 relates to the DHW plate heat exchanger or flow switch, the fix is less severe, but still requires a professional.
How much does it cost to fix a Remeha E13 fault in the UK?
For the most common cause — primary heat exchanger replacement — expect to pay in the region of £300–£750 in total, covering the engineer's call-out and diagnosis (typically £100–£150), parts (£150–£300 for the heat exchanger itself, sometimes more for OEM components), and labour. Regional rates vary considerably: engineers in London using a national company may charge £100–£150 per hour, while a local engineer in the North of England might charge closer to £50 per hour. For the less serious DHW plate heat exchanger variant on combi models, costs are significantly lower — often £100–£200 all in. If your boiler needs a full new primary heat exchanger and is already over ten years old, a new boiler installation (typically £2,000–£2,500) may work out better value in the long run.
Is my Remeha heat exchanger covered by warranty?
Remeha offers a five-year warranty on heat exchangers on eligible models. If your boiler is within this period and has been regularly serviced by a registered engineer, you may be entitled to a warranty repair at no parts cost. Contact Remeha's after-sales team directly, or reach out to one of their approved service agents, before agreeing to any chargeable repair. Keep your service records to hand as these are typically required to validate a warranty claim.
My Remeha Avanta Plus has E13 but only the hot water has stopped — is it the same fault?
Not necessarily. On the Avanta Plus combi, E13 can indicate a problem with the DHW plate heat exchanger or the domestic hot water flow switch rather than the primary heat exchanger. If your central heating is working normally and only hot water has failed, this is a more encouraging sign — it suggests the primary heat exchanger may be unaffected. The plate heat exchanger may be scaled up (common in hard water areas) and could potentially be descaled rather than replaced, which is a much cheaper fix. A Gas Safe engineer should carry out a diagnosis to confirm which component is at fault before any work is done.