Potterton Promax HE Plus, Promax SL, Promax FSB, Gold H and Gold Heat fault codes
Built 2008–2019
Heat-only with three LEDs (mains, boiler on, lockout). The pattern table lives in the installer manual and is summarised below; no code pages.
Codes on the Promax HE Plus, Promax SL, Promax FSB, Gold H and Gold Heat follow the same Potterton scheme as the rest of the range. Where a code behaves differently on this generation, the code page says so.
Potterton fault codes
Every published Potterton code. Open a code to see which models and years it applies to.
- E119The 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.Get it checked
- E133Gas 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.Get it checked
- E118The 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.Get it checked
- E110Safety thermostat operated — the primary water overheated — on every Potterton code display. One reset is permitted (5 s knob or 1–3 s button); a second E110 is a circulation fault for an engineer.Get it checked
- E125Circulation fault (primary circuit) on every Potterton code display — the water did not warm as expected after lighting, or overshot twice. Pump, air or sludge; an engineer job after one reset.Get it checked
- E128Flame failure during normal operation on the Potterton Assure and Promax Ultra: the burner was lit and went out. Resettable; recurring E128 wants an engineer.Get it checked
- E28Three meanings on Potterton: incorrect PCB fitted (Gold Combi HE 2007), flue NTC fault (2008–2014 and all digital displays), or flue NTC, air pressure switch, blocked flue or condensate (2015–2019 combis).Get it checked
- E130Flue NTC operated — the flue gas got too hot — on every Potterton code display. Reset once as the user guide allows; if it returns the heat exchanger or flue needs an engineer.Get it checked
- E160Fan or fan wiring fault on every Potterton code display: the fan did not start or reach speed. A component fault in the user guide's words — note it and call; no reset is offered.Get it checked
- E20Central heating NTC fault on every Potterton code display — the flow temperature sensor is open or short circuit. The user guide says note the code and call; no reset is offered.Get it checked
- E193The rotary-switch Pottertons' pre-ignition pump check has failed: the pump ran and the flow never proved. Same causes as E125; no owner reset is offered.Get it checked
- E135The 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.Get it checked
- E109The digital-display Pottertons' pre-ignition pump check — Assure Combi, Assure System, Promax Ultra. The flow never proved, so the burner was not lit. Bleed and check pressure; then an engineer.Get it checked
- E117Primary water pressure above 2.7 bar on the Potterton Promax Ultra. Usually an over-filled system or a failed expansion vessel; an engineer should let it down and find out which.Get it checked
- E50Hot water NTC fault on rotary-switch Potterton combis — Promax Combi, Titanium, Gold Combi, Store, Heatmax. The domestic hot water sensor is open or short. Note the code and call.Get it checked
- E09The 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.Get it checked
- Red light flashingPotterton 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.Get it checked
- E15The 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.Get it checked
- E384The 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.Get it checked
- E270Circulation fault (dry fire) on the Potterton Assure and Promax Ultra: the burner lit with too little water passing the heat exchanger. Not resettable by the owner; engineer.Get it checked
- E134The Promax Ultra's timed-out ignition: the gas valve was held open for the whole ignition period and nothing arrived to light. Check the supply, reset once, then call.Get it checked
- E154Flow/return sensor temperature test on the Potterton Assure and Promax Ultra: the two heating sensors disagree with each other or with physics. Usually circulation; sometimes a sensor.Get it checked
- E321Hot water NTC fault on the Potterton Assure Combi and Promax Ultra — the digital-display successor to E50. Shown with a spanner; hot water stops, engineer needed.Get it checked
- E83Communication 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.Usually simple to fix
- E40Central heating return NTC fault on the Potterton Assure and Promax Ultra. The return sensor is open or short. Shown with a spanner; engineer.Get it checked
- E103Codes 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.Get it checked
- E55Calibration 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.Usually simple to fix
- E131Interruption 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.Usually simple to fix
Other Potterton models
- Assure Combi and Assure System
- Assure Heat, Titanium Heat and Ultra Heat
- Gold Combi HE, Gold Combi HE A, Gold Combi and Gold System
- Profile, Kingfisher, Netaheat, Performa
- Promax Combi HE Plus, HE A and Promax Combi 24/28/33
- Promax Heatmax HE
- Promax Store HE and Promax Store
- Promax System HE Plus, HE A and Promax System 12–32
- Promax Ultra Combi
- Suprima and Suprima HE
- Titanium Combi