E44 Boiler Fault Code: What It Means on Every Brand

The E44 fault code appears on 5 brands — Alpha, Andrews, Keston, Ravenheat and Remeha — and it does not mean the same thing on each. The same two or three characters can signal a pressure problem on one boiler and an ignition fault on another, so identify your brand first and use the table below to jump to the right page.

Up to: Lockout — engineer likely 5 brands use this code Meaning differs by brand

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What E44 means	Severity	DIY?
AAlpha	The Alpha E44 fault code points to a problem with a central heating temperature sensor — most likely an NTC thermistor monitoring the flow or return water temperature. Full guide →	Lockout — engineer likely	No
AAndrews	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. Full guide →	Lockout — engineer likely	No
KKeston	The E44 code on Keston boilers signals that the system water pressure has fallen below the acceptable threshold — typically under 0.5 bar. Full guide →	Lockout — engineer likely	Some checks
RRavenheat	E44 is the last of Ravenheat's E42–E44 group of 'different temperature' faults. Full guide →	Lockout — engineer likely	Some checks
RRemeha	The E44 code tells you that the boiler's control system has run an internal check on its configuration settings and found something it doesn't like — either a value is missing, out of… Full guide →	Lockout — engineer likely	Some checks

E44 brand by brand

Alpha E44

The Alpha E44 fault code points to a problem with a central heating temperature sensor — most likely an NTC thermistor monitoring the flow or return water temperature. NTC thermistors are small electronic components that measure water temperature by changing their electrical resistance; they feed this data continuously to the boiler's PCB so it knows when to fire and when to shut down. When the PCB receives a reading outside the expected range — or no reading at all — it logs E44 and locks the boiler out to prevent unsafe operation. It is worth noting that E44 does not appear by name in all publicly available Alpha fault-code databases, so its exact meaning can vary slightly by model. The codes on either side of it are well-documented: E40 covers a central heating return NTC fault, E43 relates to a PCB communication failure, and E50 flags a domestic hot water NTC fault. If your display shows something close to E44 (such as E40 or E43), check those definitions too. Always cross-reference your boiler's own installation or user manual, or contact Alpha's customer support line, to confirm the precise definition for your specific model.

Causes, fixes & costs for Alpha E44 → · All Alpha codes

Andrews E44

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.

Causes, fixes & costs for Andrews E44 → · All Andrews codes

Keston E44

The E44 code on Keston boilers signals that the system water pressure has fallen below the acceptable threshold — typically under 0.5 bar. When this happens, the boiler shuts itself down as a protective measure and will not restart until the pressure is restored and the boiler is manually reset. You can confirm the fault by checking the pressure gauge on the boiler's front panel; a reading below 1 bar confirms low pressure is the culprit.

Causes, fixes & costs for Keston E44 → · All Keston codes

Ravenheat E44

E44 is the last of Ravenheat's E42–E44 group of 'different temperature' faults. The control board continuously cross-checks the readings coming back from its temperature sensors, and E44 indicates that check has failed — one reading is inconsistent with the others or with what the boiler knows it is doing (for example, a sensor barely moving while the burner is firing, or two sensors disagreeing far beyond the normal flow/return spread). The board suspends operation because it can no longer trust its picture of water temperature. As with its siblings, the real-world cause is nearly always a failing NTC sensor or its wiring, or a circulation problem — pump, air or blockage — making genuine temperatures diverge.

Causes, fixes & costs for Ravenheat E44 → · All Ravenheat codes

Remeha E44

The E44 code tells you that the boiler's control system has run an internal check on its configuration settings and found something it doesn't like — either a value is missing, out of range, or has become corrupted. Remeha refers to these as 'parameter errors', and the two specific values most commonly at fault are labelled dF and dU, which are unique configuration figures printed on the data plate fixed underneath the boiler. Because the boiler cannot be sure it is set up correctly, it locks out as a precaution until the settings are verified and restored.

Causes, fixes & costs for Remeha E44 → · All Remeha codes

Frequently asked questions

Is the E44 fault code the same on every boiler?

No. E44 means different things on different brands — see the table above. Always identify your boiler's brand (it is printed on the front casing) before acting on any advice about the code.

Can I fix a E44 fault myself?

On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. Where the code is a simple pressure or reset condition, that may be all it needs. Never open the boiler casing yourself.

Who should I call about a E44 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.