Baxi E87 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E87 fault code mean?
The E87 fault code on a Baxi boiler signals an internal communication failure — the boiler's main printed circuit board (PCB) has lost contact with one or more components it needs to talk to, most commonly the gas valve or an external control unit. E87 sits within the E83–E87 family of codes, all of which relate to communication breakdowns within the system. Baxi classifies E87 as a communication error between the PCB and a connected control or component, and in some cases the boiler may attempt to self-reset. If it locks out repeatedly, however, an engineer will need to investigate the root cause rather than simply resetting the unit.
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
- Loose or damaged wiring connections Common
The most frequent trigger for E87 is a wiring harness that has worked loose over time — typically between the PCB and the gas valve, or between the PCB and an external control module. Vibration from normal boiler operation can gradually loosen connectors, and corrosion in damp boiler cupboards can degrade contact quality further.
- External controls lost synchronisation Common
If you have a wireless room thermostat or programmer paired to the boiler, a loss of signal — caused by a flat battery, interference, or a brief power interruption — can break the communication link and trigger E87. The boiler cannot confirm it is receiving valid control signals and raises the fault as a precaution.
- PCB fault or failure Sometimes
The PCB itself can develop faults, particularly on older boilers or after a power surge. If the processor or communication circuitry on the board is faulty, it will be unable to exchange data correctly with the gas valve or other components, producing a persistent E87 lockout that resetting alone will not clear.
- Gas valve communication fault Sometimes
The gas valve on modern Baxi boilers contains its own electronics and communicates digitally with the PCB. A fault within the valve's control circuit, or a break in the dedicated communication wiring between valve and board, can produce an E87 without any obvious mechanical problem with the valve itself.
- Power interruption or voltage fluctuation Rare
A brief mains power cut or an unstable supply voltage can interrupt the communication handshake between components and leave the boiler in a fault state even after power is restored. A single reset usually clears this, so if the fault returns it is unlikely to be the sole cause.
How to fix it
- Reset the boiler once or twice DIY safe
Locate the reset button on the boiler's front panel — on most Baxi models it is a dedicated button marked with a flame or reset symbol. Press and hold it for 3–5 seconds until the display changes and the boiler attempts to restart. Allow two to three minutes for the full start-up sequence. If E87 clears and the boiler runs normally, monitor it over the next few hours. Limit resets to two or three attempts; repeated lockouts suggest a genuine fault that resetting will not fix.
- Check and restore power to external controls DIY safe
If you use a wireless room thermostat or programmer, check its display is active and that its batteries are not flat. Replace batteries if in doubt, then follow the manufacturer's pairing instructions to re-sync the controller with the boiler. Ensure any wired programmer or time clock has not lost its settings after a power cut.
- Verify the gas supply is on DIY safe
Confirm that the isolation valve on the gas supply pipe to the boiler is fully open (handle in line with the pipe) and that other gas appliances in the property — a hob or gas fire — are working normally. If there is no gas elsewhere in the property, contact your gas supplier rather than an engineer.
- Inspect visible wiring for obvious damage DIY safe
With the boiler switched off at the mains, take a visual look at any wiring you can see without removing covers — check for cables that appear pinched, melted, or disconnected at plug-in connectors. Do not remove any boiler casing panels or touch internal components. If you spot obvious external damage to a cable, note it to report to the engineer.
- Call a Gas Safe registered engineer to diagnose and repair Gas Safe engineer
If E87 returns after one or two resets, or if the boiler will not restart at all, contact a Gas Safe registered engineer. They will test the communication circuits, re-seat or replace wiring harnesses, check the gas valve electronics, and assess the PCB. Do not attempt to open the boiler casing, probe internal wiring, or touch the gas valve — this work legally requires Gas Safe registration and carries serious safety risks if carried out by an unqualified person.
Parts you may need
- Baxi PCB (main circuit board) · from £220
- Gas valve assembly · from £180
- Wiring harness / loom · from £45
- Wireless receiver module · from £55
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 £80–£380, depending on the underlying cause.
Frequently asked questions
Can I fix Baxi E87 myself just by resetting the boiler?
A reset is always the right first step and will clear E87 if it was triggered by a temporary power blip or a momentary communication hiccup. However, if the fault returns after one or two resets, the underlying cause — loose wiring, a faulty PCB, or a gas valve communication issue — will need a Gas Safe engineer to diagnose and repair. Repeated resets without fixing the root cause can mask a worsening problem.
How much does it cost to fix a Baxi E87 fault in the UK?
For most homeowners the repair falls between £80 and £380. A call-out and diagnostic fee alone is typically £60–£100, and if the fix is simply re-seating a loose connector or re-pairing a wireless controller, you may pay little more than that. A gas valve repair or replacement usually adds £150–£300 in parts and labour. PCB replacement is the most expensive common outcome — parts and labour together typically come to £300–£500, though in London and the South East you may pay toward the top of that range. Full PCB replacement on an older or less common Baxi model can occasionally exceed £500; if that quote approaches or exceeds half the cost of a new boiler, it is worth considering a replacement instead.
Is Baxi E87 dangerous — should I turn the boiler off?
E87 itself is a communication fault rather than a gas leak or carbon monoxide warning, so it does not present an immediate safety emergency. The boiler will typically lock out and stop firing as a precaution. You do not need to evacuate your home, but you should not continue forcing restarts if the fault keeps returning. Leave the boiler off and arrange an engineer visit. If you ever suspect a gas leak — smell gas or hear an unusual hiss — leave the property immediately and call the National Gas Emergency Service on 0800 111 999.
Could a wireless thermostat cause the Baxi E87 code?
Yes — this is one of the more straightforward causes and is worth checking before calling an engineer. If your Baxi boiler is paired with a wireless room thermostat or smart control, a flat battery, signal loss, or a pairing that has dropped out can break the communication link and trigger E87. Replace the batteries in the thermostat, re-pair it following the manufacturer's instructions, and attempt a boiler reset. If E87 does not return, the wireless control was the culprit and no further work should be needed.