Ravenheat E44 Fault Code: Causes, Fixes & Repair Costs
What does the Ravenheat E44 fault code mean?
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.
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
- NTC sensor failing or out of calibration Common
A thermistor whose resistance curve has drifted reports a temperature that no longer matches reality; the board's cross-check catches the inconsistency and raises E44. Replacement is cheap and definitive once identified.
- Circulation fault (pump, sludge or closed valve) Common
If water is not moving properly through the heat exchanger, the sensor nearest the burner heats rapidly while the other lags, producing a spread the comparison logic rejects. Pump performance and system flow are the second thing an engineer checks.
- Wiring or connector resistance Sometimes
Corrosion or a loose spade connector in one sensor circuit skews only that reading. Because the fault is electrical rather than thermal, it can be intermittent — appearing as the boiler warms and connections expand.
- Control board measurement fault Rare
Rarely the sensors and loom test fine and the fault lies in the PCB's measuring inputs. This is a last-resort diagnosis by elimination.
How to fix it
- Top up pressure if low and bleed radiators DIY safe
Bring the system to around 1.2 bar cold and bleed any airlocked radiators — both remove the innocent causes of abnormal temperature spreads before anyone starts replacing parts.
- Reset once DIY safe
A single reset tells you whether the discrepancy was transient. If E44 returns during or shortly after firing, leave it — repeated resets add wear without information.
- Note the boiler's behaviour before lockout DIY safe
Did radiators heat? Was there kettling or gurgling? Did hot water run lukewarm? These observations help the engineer split sensor faults from circulation faults quickly.
- Engineer: test both sensors, the loom and the pump Gas Safe engineer
A Gas Safe registered engineer will measure each NTC against its resistance table hot and cold, inspect connectors, and verify pump output. Whichever element fails is replaced, and the boiler is run up to confirm the readings now reconcile.
Parts you may need
- Flow/return NTC thermistor · from £20
- Circulation pump · from £120
- Control PCB · from £170
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–£300, depending on the underlying cause.
Frequently asked questions
Is Ravenheat E44 serious?
It is not a combustion or gas-safety event — it is the boiler declining to run while its temperature readings disagree. The underlying part is usually an inexpensive sensor, though a circulation fault (pump or sludge) costs more to put right. It does mean no heating or hot water until resolved, so treat it as a prompt repair rather than an emergency.
Why does E44 keep coming back after I reset it?
Because the cause is physical: a drifted sensor keeps mis-reporting, and a circulation problem keeps producing abnormal temperature spreads every time the burner fires. Resetting only restarts the test. After one or two returns, book a Gas Safe registered engineer.
What will the repair cost?
Typically £100–£300: sensor replacements sit at the bottom of that range, pump work toward the top. Prices vary by region — get a written quote.