Warmflow E31 Fault Code: Causes, Fixes & Repair Costs
What does the Warmflow E31 fault code mean?
The E31 code appears on Warmflow Agentis Series boilers when the main control board can no longer communicate properly with the remote control unit. In plain terms, the data link between the boiler and its remote has broken down — either in the wiring, at a connector, or within the remote unit itself. The code may display in blue (warning) or red (serious error) on the LCD. Two closely related codes to be aware of are E32 (an MMI/control PCB error originating at the remote control end) and E62 (an MMI/control PCB error on the boiler itself); an engineer investigating E31 will often check for these as well.
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
- Damaged or pinched remote control cable Common
The cable running between the remote unit and the boiler can become kinked, pinched by a door frame, or physically damaged over time. Even a small break in the conductor is enough to drop the communication signal and trigger E31.
- Loose or corroded connector at either end Common
The plug-and-socket connections at the remote control and at the boiler's control panel can work loose through vibration, or corrode in damp conditions. A poor contact here mimics a full cable break.
- Faulty remote control unit Sometimes
The remote control module itself can develop an internal fault — a failed component on its circuit board or a cracked solder joint — causing it to stop communicating correctly even though all cables appear intact.
- Damaged internal wiring inside the control panel Rare
Less often, the wiring loom inside the boiler's control enclosure develops a fault at the point where the remote cable terminates. This requires the panel to be opened and inspected, which must only be done by a qualified engineer.
How to fix it
- Check whether the boiler has simply lost power or been disturbed DIY safe
Before assuming a wiring fault, confirm the boiler is powered and that the remote control unit is properly seated in its mounting. A loose remote that has been accidentally knocked can sometimes lose contact.
- Reset the boiler (up to 2–3 times) DIY safe
A one-off communication glitch can occasionally be cleared by resetting the boiler using the button or procedure described in your Agentis user guide. If E31 returns immediately or after a short time, a reset alone will not resolve the underlying fault.
- Visually inspect the full length of the remote control cable DIY safe
Trace the cable from the remote unit to where it enters the boiler and look for any obvious kinking, crushing, or chafing. Do not probe terminals or open the boiler casing — limit this to a visual check only.
- Have an engineer check and reseat all cable connectors Gas Safe engineer
A qualified engineer will unplug and recheck the connectors at both ends of the remote cable, cleaning away any corrosion and ensuring each connector is firmly seated. This is often enough to clear the fault.
- Have an engineer test the remote control cable continuity Gas Safe engineer
Using a multimeter, the engineer can confirm whether the cable itself is intact or has an open circuit. A faulty cable is straightforward to replace.
- Have an engineer inspect internal wiring in the control panel Gas Safe engineer
If the external cable and connectors are sound, the engineer will open the control panel to check the wiring loom inside. Live terminals may be present, so this work must never be attempted by a homeowner.
- Have the remote control unit tested or replaced Gas Safe engineer
If all cabling and connections are confirmed good, the remote unit itself is likely at fault. The engineer will either test it with a known-working unit or arrange for a replacement remote control module.
- Call a qualified heating engineer if the fault persists Gas Safe engineer
If none of the above steps resolve E31, or if related codes E32 or E62 also appear, contact a qualified heating engineer (Gas Safe registered if any gas work is needed). Warmflow's technical support team can also help direct the engineer to the correct fix if you quote the E31 code when calling.
Parts you may need
- Remote control cable (replacement) · from £25
- Remote control unit (Warmflow Agentis) · from £85
- Control panel wiring loom · from £45
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–£320, depending on the underlying cause.
Frequently asked questions
Can I fix the Warmflow E31 fault myself?
The checks you can safely carry out yourself are limited: confirm power is on, reseat the remote unit if it looks dislodged, run a visual check along the cable, and try resetting the boiler a couple of times. Beyond that, inspecting connectors, testing cables, and opening the control panel requires a qualified heating engineer. E31 does not involve the gas circuit, so a Gas Safe registration is not strictly required for the repair itself — but most competent heating engineers are Gas Safe registered anyway, which is a useful quality indicator.
How much does it cost to fix a Warmflow E31 fault?
If the fault is down to a loose connector or a damaged cable, repair typically costs £100–£200 including labour. Replacing the remote control unit itself usually brings the total to around £200–£320. In the unlikely event the fault has caused or is accompanied by a control PCB failure (watch for E62 alongside E31), PCB replacement can cost £350–£500 or more including parts and labour — but that is not the typical outcome for E31 alone.
What is the difference between Warmflow fault codes E31, E32, and E62?
All three relate to the boiler's MMI (man-machine interface) communication system. E31 means the boiler has lost contact with the remote control unit — usually a cable or remote hardware problem. E32 points to a PCB-level fault within the remote control unit itself. E62 indicates a PCB fault on the boiler's own control board. An engineer investigating E31 will often check whether E32 or E62 are also present, as the root cause can overlap.
Will the E31 fault affect my Warmflow warranty?
Warmflow Agentis boilers carry a 24-month parts and workmanship warranty from the manufacture date, with a 5-year warranty on the water jacket and thermal store for combi models. To keep the warranty valid, the boiler must be serviced annually by a qualified engineer. If your boiler is within the warranty period, contact Warmflow before arranging a repair, as the fault may be covered — especially if no annual service has been missed.