Andrews E44 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews E44 fault code mean?
E44 on an Andrews water heater is a control error meaning the two processors in the appliance's control system have stopped communicating reliably with each other. The MAXXflo range runs its controls across a main processor and a display/interface processor; when the data link between them fails its checks, the unit raises E44 and stops normal operation rather than run without a trustworthy control chain. In a commercial plant room this matters quickly — a locked-out water heater means no stored hot water for the building — so E44 is usually treated as a call-out rather than something to watch. The root cause is electrical: connection, board or, occasionally, supply-quality problems.
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
- Loose or degraded interconnection between boards Common
The ribbon or harness linking the main control board and the display/interface board is the usual weak point. A connector disturbed during servicing, vibration, or corrosion in a damp plant room interrupts the data link and triggers E44.
- Failed display/interface or main control board Sometimes
If either processor board fails, the partner loses its counterpart and reports the communication error. Which board is at fault is determined by substitution and testing — a job for an engineer with the service manual.
- Electrical supply interference or poor earthing Rare
Commercial plant rooms can suffer supply noise, shared-circuit interference or earthing issues that corrupt board-to-board communication intermittently. If E44 recurs and boards test healthy, the supply and earth arrangements deserve scrutiny.
How to fix it
- Record the code and isolate repeat behaviour DIY safe
Note whether E44 appeared once or keeps returning after reset, and whether anything electrical changed in the plant room recently. This history genuinely speeds the engineer's diagnosis.
- Try a single reset DIY safe
E44 is a lockout fault and can be reset via the unit's reset control once. If communication has genuinely recovered it will run; if the code returns, leave it locked out and arrange service.
- Do not open the appliance or disturb wiring Gas Safe engineer
These are commercial gas appliances with mains-voltage control gear. Checking connectors and boards is strictly for a Gas Safe registered engineer — for this class of appliance, one holding commercial gas qualifications.
- Have an engineer check the interconnections and boards Gas Safe engineer
The engineer will inspect and reseat the board interconnections, test each processor board per the service manual, and replace whichever has failed. If the fault is intermittent, they should also verify supply quality and earthing before signing it off.
Parts you may need
- Display/interface board · from £180
- Main control PCB · from £320
- Board interconnection harness · from £40
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 £150–£450, depending on the underlying cause.
Frequently asked questions
What does E44 mean on an Andrews water heater?
It is a control error: the two processors that share control of the appliance — the main board and the display/interface board — have lost reliable communication. The unit locks out rather than run without a verified control chain, and the fix is electrical: connections, one of the boards, or occasionally supply quality.
Can I reset an Andrews E44 fault?
Once, yes — E44 is a lockout fault and the reset button will clear it if communication has recovered. If it returns, stop resetting and book service: an intermittent processor link is not going to heal itself, and repeated resets just delay the proper repair while the building has no stored hot water.
Who should work on an Andrews MAXXflo?
A Gas Safe registered engineer — and because these are commercial water heaters, one whose registration covers commercial appliances. Domestic-only registration does not cover this class of plant.