Potterton E83 fault codewhat it means and how to fix it
Communication error on the Potterton Assure and Promax Ultra: the board has lost contact with a connected control such as an OpenTherm room unit. Check the control and its wiring first.
Before you start
What control is connected to the boiler?
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.
An OpenTherm or smart control the installer set up
The control or its link is the likely fault.
Batteries, power and pairing first; then the installer.
A simple timer or thermostat, or nothing
The boiler board has an internal communication fault.
Engineer.
What E83 means
The Assure and Promax Ultra tables carry "83 — Communication error" and say nothing more about it. The Assure user guide gives the context in a different section: "OpenTherm controller. Your installer will advise you when this type of control is connected to the boiler. If so, any change to the boiler settings ... must be made using the OpenTherm controller not the boiler control panel."
An OpenTherm or other bus-connected control talks to the boiler continuously, and 83 is the board reporting that the conversation stopped — a control unplugged, its wiring broken, its batteries flat, or the control itself failed. It is not in either manual's list of resettable codes, but it is also not a lockout in the sense the ignition codes are; it clears when the control is heard again. The Promax, Titanium and Gold have no equivalent because their boards take only a switched-live demand from a conventional programmer.
If your Assure has only a simple timer or thermostat wired to it and shows 83, the fault is inside the boiler's own control circuit and an engineer is needed; if it has an OpenTherm control, the control is where to start.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| OpenTherm or bus control disconnected or flat | Batteries in a wireless room unit, a receiver unplugged, or a two-core cable disturbed. The boiler cannot tell the difference between a silent control and a missing one. | Common |
| Control wiring fault | A break or short on the two-wire bus between control and boiler, often where the cable enters the boiler or at a junction box. | Occasional |
| Control or boiler board fault | Either end of the link can fail. Diagnosed by substitution once the wiring is proven. | Occasional |
What to try yourself
Look at the room control. If it has a screen, is it lit and showing a connection? Replace its batteries if it takes them; check any receiver box is plugged in and its light is on.
If the control has a link or pairing indicator, follow its own manual to re-establish the link. The boiler code should clear on its own once communication is back.
If 83 stays with the control apparently working, or you have no such control fitted, contact your installer or Baxi Customer Support.
Get a Gas Safe registered engineer to look at your Potterton E83
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.
What it costs to fix
Typical repair cost
£0–£250
Time on site
10 minutes
Free if batteries or pairing. Call-out and wiring repair £60–£120. Replacement room control £80–£250.
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 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
- E103Get it checkedCodes 103, 104, 107 and the word "Bat" on the Potterton Assure: the user guide names them only to say contact your installer or Baxi Customer Support. They concern the safety board's battery.Related: electronics and power
- E55Usually simple to fixCalibration required on the Potterton Promax Ultra — shown after the gas valve or board is replaced until the engineer runs the calibration routine. Not a fault an owner will meet unprompted.Related: electronics and power
- E131Usually simple to fixInterruption of power supply while in fault mode — the Potterton Promax Store only. The power went off while another code was showing. Restore power, read the code that follows.Related: electronics and power
- E119Get it checkedThe sealed system on a rotary-switch Potterton — Promax, Titanium, Gold, Heatmax — has dropped below half a bar. The window shows E1 and then 19. Fill to 1–1.5 bar and it clears itself.Related: same brand
- 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: same brand
- E118Get it checkedThe digital-display Pottertons — Assure Combi, Assure System, Promax Ultra — have dropped below half a bar on the heating circuit. Repressurise to 1–1.5 bar and the boiler restarts on its own.Related: same brand
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.