Andrews E0 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews E0 fault code mean?
The E0 fault code on Andrews boilers most commonly points to a problem with the return or flow temperature sensor — the sensor may have failed, developed a short circuit, or become disconnected from its wiring harness. On some Andrews model ranges, E0 can instead indicate an ignition lockout, meaning the boiler attempted to light the burner but no flame was detected. Because Andrews is a specialist commercial and semi-commercial brand with model-specific fault tables, the exact meaning can vary between product ranges. Always cross-reference with your specific Andrews installation manual or contact Andrews technical support to confirm which interpretation applies to your unit.
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
- Faulty or degraded NTC temperature sensor Common
The return or flow temperature sensor (an NTC thermistor) can fail over time due to heat cycling and general wear. When its resistance reading falls outside the expected range, the boiler control board flags an E0 fault and shuts down to prevent unsafe operation. This is the most frequently reported cause on Andrews and closely related commercial units.
- Loose or disconnected sensor wiring Common
Vibration, age, or previous servicing work can cause the wiring connector to the temperature sensor to work loose or pull away entirely. The control board sees an open circuit and interprets this as a sensor fault, triggering the E0 code even though the sensor itself may be perfectly serviceable.
- Short circuit in the sensor circuit Sometimes
Physical damage to the sensor cable — such as chafing against a hot surface or a pinched wire — can create a short circuit. This produces an abnormal resistance reading at the PCB input and will trigger the E0 lockout.
- Ignition failure or no flame detected Sometimes
On Andrews models where E0 signals an ignition lockout rather than a sensor fault, the boiler has tried to establish a flame and failed. This can stem from a worn ignition electrode, a faulty ignition lead, low gas supply pressure, or a blocked condensate pipe preventing the boiler from starting its firing sequence safely.
- PCB input failure Rare
If the sensor and its wiring both test as healthy, the fault may lie with the PCB channel that reads the sensor signal. PCB faults are less common but can produce persistent E0 codes that resist all other remedies.
How to fix it
- Check your Andrews boiler manual or label for the E0 definition DIY safe
Andrews produce several distinct product ranges, and the E0 code meaning can differ between them. Locate the model number on the boiler's data plate and consult the installation or user guide, or ring Andrews technical support, before proceeding. This ensures you are diagnosing the right fault.
- Verify the gas supply is active DIY safe
Check that other gas appliances in the property — a hob or fire — are working normally. If nothing gas-powered is working, contact your gas supplier rather than an engineer, as the issue is with the supply rather than the boiler.
- Check system pressure DIY safe
Look at the pressure gauge on the boiler. Most systems should read between 1.0 and 1.5 bar when cold. If it is below 1 bar, top up using the filling loop according to your user guide, then attempt a reset. Abnormal pressure is not usually the direct cause of E0, but it is good practice to rule it out first.
- Inspect and thaw the condensate pipe if weather is cold DIY safe
In freezing conditions, the plastic condensate drain pipe (typically running outside or through an unheated space) can ice up and cause the boiler to lock out. Pour warm — not boiling — water along the pipe to thaw it, then reset the boiler. Insulating the pipe afterwards helps prevent a repeat.
- Attempt a single boiler reset DIY safe
Press and hold the reset button as described in your Andrews user guide. Allow the boiler to complete its start-up sequence. If it runs normally, monitor it over the next hour. If the E0 code returns promptly, do not reset it again — repeated resets on an unresolved fault can stress the ignition electrode and PCB. Stop and move to the next step.
- Have a Gas Safe engineer inspect the temperature sensors and wiring Gas Safe engineer
A registered engineer will open the boiler casing, locate the return and flow NTC sensors, and test their resistance with a multimeter. Readings outside the manufacturer's specified range confirm a failed sensor. They will also check connectors and wiring for corrosion, looseness, or damage. This work requires removal of the casing and is not legal for an unregistered person to carry out on a commercial or domestic gas appliance.
- Allow the engineer to replace the faulty sensor or repair the wiring Gas Safe engineer
If a sensor has failed, the engineer will fit a matching replacement and clear the fault code. If damaged wiring is found, they will repair or re-route it to eliminate the short or open circuit. Both jobs typically resolve E0 when it is sensor-related.
- If E0 relates to ignition, have the engineer inspect the ignition components Gas Safe engineer
For ignition-lockout variants of E0, the engineer will examine the ignition electrode for wear or carbon deposits, test the ignition lead for continuity, and check the flame-sensing electrode. Worn components will be replaced. Gas valve output pressure will also be verified — gas valve work must only be carried out by a Gas Safe engineer.
- Contact Andrews technical support or an Andrews-accredited engineer if the fault persists Gas Safe engineer
Because Andrews is a specialist commercial brand, standard domestic heating engineers may not have model-specific fault data. Andrews technical support can provide wiring diagrams and resistance values for your exact unit, and can recommend accredited service agents if the fault proves complex or a PCB replacement is needed.
Parts you may need
- NTC return temperature sensor · from £35
- NTC flow temperature sensor · from £35
- Ignition electrode · from £25
- Ignition lead · from £20
- Flame sensing electrode · from £30
- Boiler PCB (control board) · from £220
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–£350, depending on the underlying cause.
Frequently asked questions
Is the Andrews E0 code always a sensor fault, or could it mean something else on my model?
It depends on your specific Andrews product range. On units closely related to the Remeha commercial platform, E0 typically flags a return or boiler temperature sensor fault — either failed, disconnected, or short-circuited. On other Andrews models, E0 can indicate an ignition lockout where no flame was detected during start-up. The safest approach is to check the data plate on your boiler, find the model number, and either consult the original manual or call Andrews technical support directly, as their fault tables are model-specific and not always published in mainstream trade guides.
Can I fix an Andrews E0 fault myself?
A few basic checks are safe for a homeowner: confirming the gas supply is on, topping up system pressure if it is low, thawing a frozen condensate pipe in cold weather, and attempting one reset. Beyond that, all internal work — testing sensors with a multimeter, replacing components, or inspecting gas-side parts — must be carried out by a Gas Safe registered engineer. Andrews units are often commercial or semi-commercial appliances, which makes compliance with gas safety legislation especially important.
How much does it cost to fix an Andrews E0 fault in the UK?
For the most common causes — a failed NTC sensor or a worn ignition electrode — expect to pay roughly £150 to £350 including call-out, parts, and labour. If the fault turns out to be a PCB failure, costs can rise to £400 or more, since commercial-grade PCBs are more expensive than domestic equivalents. Prices in London and the South East tend to be higher than elsewhere due to local labour rates. Getting two or three quotes from Gas Safe engineers familiar with commercial water heaters is worthwhile before committing to a repair on an older Andrews unit.
Should I keep resetting my Andrews boiler while I wait for an engineer?
One reset is reasonable to check whether the fault clears on its own. If the E0 code comes back straight away or within a short time, stop resetting the boiler. Repeatedly cycling the ignition sequence on a unit with an underlying fault puts unnecessary stress on the ignition electrode and can cause secondary damage to the PCB. Leave the boiler in its locked-out state and arrange for a Gas Safe engineer to attend — this is safer and usually cheaper in the long run.