This fault can involve incomplete combustion and carbon monoxide.
If anyone in the property feels sick, dizzy or drowsy, or you can smell gas: open the windows, leave the building, and do not switch anything on or off. Then call the National Gas Emergency Service.
0800 111 999Potterton E15 fault codewhat it means and how to fix it
The Assure and Promax Ultra's own-valve code: the board has detected a fault in the gas valve itself, not its cable. One reset allowed; then an engineer with a meter.
Take care
Get a Gas Safe registered engineer to look at your Potterton E15
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
Does the boiler run after one reset?
The right answer depends on what you can see. Pick the one that matches.
Choose the option on the left that matches what your appliance is doing, and the answer for that case appears here.
Yes
A transient. Watch it.
Mention it at the next service.
No, or it comes back
Valve, lead or board.
Engineer; expect a gas valve.
What E15 means
Code 15, the gas valve fault, sits beside 09 at the top of the Assure and Promax Ultra tables, and where 09 is the lead, 15 is the component. The valve on these boilers is an electronically driven unit (part 7683968 on the Assure) whose coils the PCB monitors; a coil reading out of range, or a drive fault, brings up 15 before ignition is attempted. It is on the reset list in both installation manuals and carries the R symbol in the Assure user guide, so the owner may press Reset once for one to three seconds.
The fault-finding chart's standing note applies — check all PCB connections for a recurring 15, then replace the PCB — but here it is more often the valve. The Promax and Titanium never show 15: their tables have no gas valve row and a valve failure appeared as E133 after the ignition attempts. A gas valve is not a part anyone but a Gas Safe registered engineer may touch, and after replacement the combustion has to be checked with an analyser, which is why the price is what it is.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Coil or drive fault inside the valve | The board reads the valve's electrical characteristics and stops if they are wrong. Age and heat cycling; no warning beforehand. | Common |
| Connector or harness | The same lead 09 reports; a poor connection can present as a valve fault rather than a cable one. | Occasional |
| PCB | The manual's fallback for a recurring code in this group. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£60–£320
Time on site
1 hour
Gas valve fitted and combustion checked £190–£300. PCB £220–£320.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Baxi / Potterton / Main gas valve
7683968£120–£240Authorised Baxi parts distributor
Price checked 28 September 2026
Baxi / Potterton / Main main PCB
£150–£320Authorised Baxi parts distributor
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Potterton fault codes
- E133Get it checkedGas supply interrupted, ignition failed or no flame detected — every Potterton generation. Confirm the gas supply, one reset (5 s on the knob, 1–3 s on the button), and call if it returns.Related: ignition and gas supply
- E128Get it checkedFlame failure during normal operation on the Potterton Assure and Promax Ultra: the burner was lit and went out. Resettable; recurring E128 wants an engineer.Related: ignition and gas supply
- E135Get it checkedThe Assure and Promax Ultra's internal-error ignition code: the control blames its own side of the gas valve rather than the supply for the flame that never came. One reset; then an engineer.Related: ignition and gas supply
- E09Get it checkedThe Assure and Promax Ultra's gas valve connection cable fault: the board has lost its wiring link to the valve. Resettable once; recurring 09 is a wiring or PCB job.Related: ignition and gas supply
- Red light flashingGet it checkedPotterton Assure Heat, Titanium Heat and Ultra Heat have no display: the illuminated button flashes red a number of times when the boiler has locked out. The count is the code.Related: ignition and gas supply
- E384Get it checkedThe Assure and Promax Ultra report a flame signal while the gas valve is shut. An electrode or PCB fault, and the Assure manual's answer is to go over the board.Related: ignition and gas supply
Own a Potterton boiler? Save it and its codes come first next time.
Related guides
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.