Remeha E10 Fault Code: No Flow Detected During Venting Cycle
The E10 code appears on Remeha boilers when the appliance detects that water is not moving through the system during its automatic venting or start-up sequence. In plain terms, the boiler is trying to push water around the circuit but is not sensing any meaningful flow. As a safety response, the boiler locks out and stops producing central heating or hot water until the underlying cause is identified and the fault 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 Remeha E10 fault code mean?
The E10 code appears on Remeha boilers when the appliance detects that water is not moving through the system during its automatic venting or start-up sequence. In plain terms, the boiler is trying to push water around the circuit but is not sensing any meaningful flow. As a safety response, the boiler locks out and stops producing central heating or hot water until the underlying cause is identified and the fault is cleared.
Common causes
- Low system water pressure Common
If the pressure in the heating circuit has dropped below around 1 bar, the boiler cannot circulate water effectively during the venting cycle and will trigger E10. This is especially common after a recent refill, a leak, or simply gradual pressure loss over time. The pressure gauge on the boiler front panel will show a reading below the normal 1–2 bar range.
- Air trapped in the system Common
Air pockets — or an airlock — can prevent water from flowing freely around the circuit. This often occurs after the system has been drained and refilled, after a heat exchanger replacement, or following any pipework work. Air essentially blocks the path that water needs to take, so even though the pump is running, no meaningful flow registers.
- Faulty or seized circulator pump Sometimes
The pump is responsible for driving hot water around your heating circuit. If the pump impeller has seized, the motor has failed, or the pump is incorrectly wired, water will not move and E10 will be triggered. A seized impeller is particularly common on pumps that have sat idle for a long time, such as at the start of the heating season.
- Sticking or seized diverter valve (combi boilers) Sometimes
On combination boiler variants, the diverter valve switches water flow between the central heating circuit and the domestic hot water heat exchanger. If this valve sticks in one position, flow around the heating circuit may be blocked, causing E10 during the venting cycle. Thermostatic radiator valves that are fully closed or seized can compound this issue.
- Wiring fault or PCB issue Rare
If all mechanical components check out, the fault may lie with incorrect wiring to the pump, or with the PCB itself failing to correctly read or drive the pump signal. This is relatively uncommon but should be considered when all other causes have been ruled out.
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 2 bar during normal operation. If it reads below 1 bar, the system needs repressurising before you attempt a reset.
- Top up system pressure via the filling loop if needed DIY safe
Locate the filling loop — usually a braided hose with one or two valves underneath the boiler. Slowly open the valve(s) and watch the gauge rise. Stop when it reaches approximately 1.2–1.5 bar, then close the valve(s) firmly. Never exceed 2 bar.
- Reset the boiler using the R button DIY safe
Once pressure is within the correct range, press and hold the reset (R) button on the boiler control panel as described in your user guide. Allow the boiler to run through its start-up sequence. If E10 clears and the boiler fires normally, monitor it over the next 24 hours to confirm pressure holds.
- Bleed the radiators to remove trapped air DIY safe
If the boiler resets but E10 returns, or if the system has recently been refilled, bleed each radiator using a radiator key, starting with the ground floor and working upward. Open the bleed valve until water (not air) trickles out, then close it. Check the boiler pressure afterwards and top up to 1.2 bar if it has dropped, then attempt another reset.
- Check that all radiator valves are fully open DIY safe
Walk around the property and make sure every thermostatic radiator valve (TRV) and lockshield valve is open rather than fully closed. A system where most or all radiators are shut off can starve the boiler of flow during the venting cycle.
- Inspect the pump for obvious signs of seizure (visual check only) DIY safe
With the boiler powered off and cooled, locate the pump (usually on the return pipe near the boiler). Check whether it feels unusually hot to the touch when the boiler has been running, or listen for any humming without water movement. Do not attempt to dismantle gas pipework or electrical connections — if you suspect the pump is seized, this is information to pass on to your engineer.
- Call a Gas Safe registered engineer to diagnose and repair the remaining fault Gas Safe engineer
If E10 persists after checking pressure, bleeding radiators, and confirming valves are open, the cause is likely a faulty pump, seized diverter valve, wiring issue, or PCB fault. All of these require a Gas Safe registered engineer to diagnose safely and carry out any repair or replacement. Do not continue resetting the boiler repeatedly — more than two or three resets without resolution can mask a developing fault.
Parts you may need
- Circulator pump (compatible replacement) · from £120
- Diverter valve assembly · from £65
- PCB (printed circuit board) · from £220
- Filling loop assembly · from £18
- Radiator bleed key · from £3
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 fix Remeha E10 myself without calling an engineer?
Some of the most common causes of E10 are homeowner-fixable. You can safely check and top up the system pressure via the filling loop, bleed the radiators to release trapped air, and attempt a boiler reset using the R button. If the fault clears after these steps, you may not need an engineer at all. However, if E10 keeps returning, or if pressure keeps dropping, there is an underlying problem — such as a faulty pump or a leak — that requires a Gas Safe registered engineer to fix safely and legally.
How much does it cost to fix a Remeha E10 fault in the UK?
The cost depends entirely on what is causing the fault. If it is simply low pressure or an airlock, an engineer callout to diagnose and reset the system typically costs £80–£130 including a standard callout fee. A seized or failed circulator pump replacement usually comes to £150–£350 all-in for parts and labour. A diverter valve repair typically falls in the £180–£280 range. PCB replacement is less common but can cost £300–£500; if that is the diagnosis, it is worth weighing the repair cost against the age of the boiler. Prices tend to be higher in London and the South East.
Why does my Remeha boiler keep showing E10 after I reset it?
If E10 returns shortly after a reset, the boiler is repeatedly detecting no flow during the venting sequence, which means the root cause has not been resolved. Repeated resets without a fix are not recommended and can mask a worsening fault. The most likely culprits for a recurring E10 are a pump that is struggling or has failed, a persistent airlock that bleeding has not fully cleared, or a sticking diverter valve on a combi model. An engineer will be able to run diagnostics, check pump operation and wiring, and pinpoint the exact cause.
Does Remeha E10 always mean the pump needs replacing?
Not necessarily. While a faulty pump is one of the most common causes, E10 simply tells you that no flow was detected during the venting cycle — which can also be caused by low water pressure or an airlock. Always check system pressure and bleed the radiators first, as these are the quickest and cheapest things to rule out. If those checks do not resolve it, then a pump issue, diverter valve problem, or wiring fault becomes more likely and an engineer should investigate.