Remeha E.00.08 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E.00.08 fault code mean?
The E.00.08 code belongs to Remeha's E.00.xx sensor fault group, used on the Quinta Ace and similar Quinta-series models that display extended dot-notation error codes. It indicates that the boiler's control board has detected an open-circuit condition on the flow (heat exchanger outlet) temperature sensor — meaning the NTC thermistor is returning no electrical signal whatsoever. Within the E.00.xx series, even-numbered codes consistently point to open-circuit (disconnected or absent) sensor signals, while odd-numbered codes indicate a short circuit. E.00.08 therefore sits alongside related codes such as E.00.20 (flue gas sensor open circuit) and E.00.21 (flue gas sensor short circuit). When the PCB cannot read the flow temperature, the boiler locks out as a safety precaution to prevent overheating or uncontrolled operation. The boiler will not restart until the fault is investigated and cleared.
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 disconnected sensor wiring connector Common
The most frequent cause. The small electrical connector linking the NTC thermistor to the PCB wiring loom can work loose over time due to vibration or previous servicing. An open circuit is exactly what the boiler sees when the connector is not fully seated, so the fault can appear even though the sensor itself is perfectly healthy.
- Sensor physically dislodged from the pipework Common
The flow NTC sensor clips onto the flow pipework and may be hidden beneath insulation. If it has slipped out of its clip — perhaps during a service or following vibration — it will no longer accurately track water temperature, and depending on the contact, can trigger an open-circuit fault.
- Damaged or broken sensor cable Sometimes
The thin wire running from the sensor back to the PCB can suffer chafing, pinching, or heat damage over time. A break anywhere along that cable presents as an open circuit to the control board, even if the sensor and connector are intact.
- Failed NTC thermistor Sometimes
The thermistor itself can fail internally — its resistance drifts outside the measurable range or the element breaks completely — producing an open-circuit reading. This is more likely on older boilers or where the sensor has been repeatedly exposed to thermal stress.
- PCB input channel fault Rare
In a small number of cases, the PCB's own sensor-reading circuitry develops a fault and cannot interpret the signal from an otherwise healthy sensor and wiring. This is a diagnosis of exclusion — only considered after the sensor and all wiring have been checked and found to be sound.
How to fix it
- Turn off the boiler and check the gas supply DIY safe
Before anything else, confirm your gas supply is working — check that other gas appliances such as a hob are operating normally. If there is no gas supply to the property, contact your gas supplier rather than investigating the boiler further.
- Attempt a boiler reset DIY safe
Press and hold the reset button on the boiler's control panel for approximately two seconds, then release. Wait a few minutes to see whether the boiler fires up successfully. If E.00.08 reappears immediately, do not continue resetting repeatedly — two or three attempts is the sensible limit before calling an engineer.
- Visually inspect the sensor location and wiring (engineer task) Gas Safe engineer
A Gas Safe engineer will locate the flow NTC sensor on the heat exchanger outlet pipework — it may be clipped under insulation — and check that it is properly seated in its clip. They will also trace the sensor cable back to the PCB, looking for any obvious damage such as chafing, kinking, or heat discolouration along the wire.
- Check and reseat all electrical connectors (engineer task) Gas Safe engineer
The engineer will disconnect and firmly reseat the wiring connector at both the sensor end and the PCB end. A multimeter resistance test across the sensor terminals will confirm whether the thermistor itself is within the expected NTC range (typically a few kilohms at room temperature, falling as temperature rises). A reading of infinite resistance confirms an open circuit.
- Replace the flow NTC thermistor if faulty (engineer task) Gas Safe engineer
If the resistance test shows the sensor is out of specification or open-circuit, the engineer will fit a replacement Remeha NTC temperature sensor (genuine part number 720480501 is commonly used on Quinta Ace models, priced around £35–£55 for the part). After fitting, they will clear the fault code and run the boiler through a full heat cycle to confirm normal operation.
- Inspect and replace the PCB if the fault persists (engineer task) Gas Safe engineer
Should a new sensor fail to clear E.00.08, the PCB's sensor-reading input is likely at fault. PCB replacement on Remeha Quinta-series boilers is a specialist task involving electrical isolation and careful commissioning. The engineer may also consult Remeha's technical support line before condemning the board, as a firmware or configuration reset is occasionally sufficient.
- Call a Gas Safe registered engineer DIY safe
Because every diagnostic and repair step beyond a visual check and reset involves electrical components inside the boiler, you must use a Gas Safe registered engineer for this fault. Ask for their Gas Safe ID card before they start work, and request a written report of the diagnosis and any parts fitted.
Parts you may need
- Remeha NTC Flow Temperature Sensor (e.g. part 720480501) · from £45
- Sensor wiring harness / loom · from £35
- Remeha Quinta Ace PCB (control board) · from £320
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 £120–£320, depending on the underlying cause.
Frequently asked questions
Can I fix Remeha E.00.08 myself?
The reset button is the only action a homeowner should take. Every other step — checking wiring, testing sensor resistance with a multimeter, replacing the thermistor, or inspecting the PCB — must be carried out by a Gas Safe registered engineer. Working inside the boiler involves live electrical components and, depending on the task, connections to the gas circuit.
How much does it cost to fix E.00.08 in the UK?
For most people, the repair involves a call-out, a sensor resistance test, and either reseating a loose connector or fitting a replacement NTC thermistor. That typically comes to between £120 and £320 including parts and labour. If the PCB turns out to be faulty, the bill can rise to £400–£600 or more — but that outcome is relatively uncommon. It is worth getting two or three quotes if a PCB replacement is recommended, and considering the boiler's age before committing to a major repair.
What is the difference between E.00.08 and other E.00.xx codes on my Remeha?
On Remeha Quinta Ace and similar models, the E.00.xx group covers a range of sensor faults. The pattern is consistent: even-numbered sub-codes (08, 20, etc.) indicate an open-circuit fault on a particular sensor, while odd-numbered sub-codes (09, 21, etc.) indicate a short circuit on the same sensor. E.00.08 specifically points to an open circuit on the flow temperature sensor. If your display shows a different sub-code, the likely sensor involved will be different, though the diagnostic approach — inspect wiring, test resistance, replace if faulty — is broadly the same.
My Remeha Quinta Ace keeps showing E.00.08 after a reset — is it getting worse?
If the fault clears after a reset but returns within minutes or hours, the most likely explanation is an intermittent connection — a wiring connector that is slightly loose rather than fully open. This is worth investigating promptly, because an unreliable flow temperature reading can cause unnecessary lockouts and, over time, stress other components. Book a Gas Safe engineer soon rather than continuing to reset the boiler repeatedly.