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Alpha Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
E-Tec, InTec & Evoke fault codes
- E1 Alpha boilers display two closely related fault codes that are often confused: E1 and E01. On older or certain Alpha… Read more →
- E10 The E10 fault code on Alpha boilers is triggered when the boiler detects that system water pressure has dropped below… Read more →
- E12 The E12 code on an Alpha boiler indicates that the differential water flow switch is stuck in the open position. This… Read more →
- E15 The E15 code appears when your Alpha boiler's PCB has issued a command to the gas valve — either to open or close — but… Read more →
- E16 The E16 code on an Alpha boiler signals a fan fault. The boiler's fan is responsible for safely drawing combustion… Read more →
- E2 The E2 fault code on an Alpha boiler means the boiler has tried to light the burner but failed to detect or hold a… Read more →
- E20 The Alpha E20 fault code most commonly indicates a flame detection or ignition failure — the boiler attempted to light… Read more →
- E23 The E23 code on an Alpha boiler indicates that the control board has detected a problem with the heating return sensor… Read more →
- E24 The E24 fault code on Alpha boilers indicates a problem within the fan, flue, or combustion air pressure circuit. The… Read more →
- E25 The E25 fault code on Alpha boilers is a protective shutdown triggered when the boiler attempts to fire but cannot… Read more →
- E27 The Alpha E27 fault code signals that the boiler has detected a problem with flame establishment or flame recognition.… Read more →
- E29 The E29 code on an Alpha boiler indicates a flue sensor fault. The boiler's control board is unable to receive a valid… Read more →
- E3 The E3 fault code on Alpha boilers indicates that the boiler has detected a problem with water circulation — either the… Read more →
- E31 The E31 code on an Alpha boiler points to a problem with the heating flow NTC thermistor — the sensor that monitors the… Read more →
- E37 The E37 fault code on Alpha boilers indicates that the boiler has detected an abnormal operating condition and locked… Read more →
- E38 The E38 code indicates that your Alpha boiler has repeatedly lost its flame signal while running. In practical terms,… Read more →
- E4 The E4 fault code on Alpha boilers signals that the boiler's control system has detected a problem with the gas valve —… Read more →
- E43 The E43 fault code on Alpha boilers (including InTec, E-Tec, and Eco2 models) has two well-documented interpretations… Read more →
- E44 The Alpha E44 fault code points to a problem with a central heating temperature sensor — most likely an NTC thermistor… Read more →
- E45 The E45 fault code on Alpha boilers signals a 'High Delta T' condition — the boiler has detected an unexpectedly large… Read more →
- E46 E46 does not appear in any publicly documented fault code list for Alpha boilers — including the E-Tec, E-Tec Plus,… Read more →
- E47 The E47 code on an Alpha boiler indicates that the boiler has detected abnormally high flue gas temperatures and has… Read more →
- E49 E49 is not a widely documented fault code across Alpha's main boiler ranges — including the E-Tec, E-Tec Plus, InTec,… Read more →
- E5 The E5 code on an Alpha boiler signals that the primary flow NTC thermistor — the sensor responsible for monitoring the… Read more →
- E51 The E51 code appears on Alpha boilers when the boiler loses communication with the Alpha Climatic room controller or… Read more →
- E6 The E6 code on an Alpha boiler points to a fault with the central heating (CH) flow temperature sensor — an NTC… Read more →
- E60 The E60 code on an Alpha boiler signals that the boiler's control board has detected a problem with the flue fan. This… Read more →
- E61 The Alpha E61 code is not listed in the standard published fault-code tables for most Alpha boiler models, which itself… Read more →
- E7 The E7 fault code on Alpha boilers most commonly indicates a temperature sensor (NTC thermistor) fault or an overheat… Read more →
- E70 The Alpha E70 fault code is not a universally standardised code that appears across all Alpha boiler models, and it is… Read more →
- E71 The E71 code is not listed in any publicly available Alpha boiler fault code documentation, and its exact meaning has… Read more →
- E75 The E75 fault code on Alpha boilers — most commonly seen on the E-Tec and E-Tec Plus ranges — indicates that the PCB… Read more →
- E76 The E76 fault code appears on certain Alpha boiler models and sits within the E7x fault code range, which on Alpha… Read more →
- E8 The Alpha E8 fault code (also shown as E08 on some displays) means the boiler has exhausted its automatic reset… Read more →
Pro-Tec Plus (system boiler) codes
- 0A1 The 0A1 fault code on Alpha boilers indicates that the boiler has attempted to light the main burner but failed to… Read more →
- 0A15 Fault code 0A15 appears on Alpha boilers — most commonly the Pro Tec Plus range — when the control board detects that… Read more →
- 0A16 Fault code 0A16 on Alpha boilers indicates that the flow temperature is not rising quickly enough after the burner… Read more →
- 0A17 The 0A17 code on an Alpha boiler sits within the '0A' fault family, which is specifically associated with overheat… Read more →
- 0A18 The 0A18 code belongs to Alpha's 0A fault-code family and tells you the boiler's PCB has detected an abrupt, unexpected… Read more →
- 0A2 The 0A2 fault code on Alpha boilers indicates that the boiler has failed to detect a flame during or after the ignition… Read more →
- 0A21 The 0A21 fault code on Alpha boilers — most commonly seen on the Pro Tec Plus range — indicates that the boiler's main… Read more →
- 0A3 The 0A3 fault code on an Alpha boiler signals that the overheat thermostat has triggered a safety lockout. On the… Read more →
- 0A30 The 0A30 code appears when the boiler's PCB detects that the flow temperature sensor (an NTC thermistor fitted to the… Read more →
- 0A31 The 0A31 fault code appears on Alpha Pro Tec Plus boilers when the flow temperature sensor (thermistor) is reading a… Read more →
- 0A37 The 0A37 fault code on Alpha boilers signals that the central heating system pressure has fallen too low for the boiler… Read more →
- 0A43 The 0A43 fault (also displayed as E43 on many Alpha models — both codes refer to exactly the same fault) means your… Read more →
- 0A44 When an Alpha boiler displays fault code 0A44, it means the return thermistor — the sensor that monitors the… Read more →
- 0A5 The 0A5 fault code on Alpha boilers indicates a fan-related fault. The boiler's control board has detected a problem… Read more →
- 0A7 The 0A7 code belongs to Alpha's 0A series of resettable anomaly codes and indicates that the flue temperature sensor… Read more →
- 0A8 The 0A8 fault code on an Alpha boiler indicates that the boiler attempted to light the burner but failed to establish a… Read more →
- 0A80 The 0A80 fault code appears on Alpha Pro Tec Plus boilers when the control board detects a problem with the electrical… Read more →
- 0A9 The 0A9 code (equivalent to the older Alpha fault code E4) appears when the boiler's control system detects a problem… Read more →
- 0E13 The Alpha 0E13 code — also displayed simply as E13 on many models — has two distinct meanings depending on which Alpha… Read more →
- 0E2 The 0E2 fault code appears on Alpha boilers when the control board loses confidence in the ionisation signal from the… Read more →
- 0E25 The Alpha 0E25 fault code (shown as plain E25 on many Alpha models) is commonly described as a 'dry fire' warning — the… Read more →
- 0E33 The 0E33 fault code (sometimes displayed simply as E33) on Alpha boilers indicates that the boiler's PCB has detected a… Read more →
- 0E34 The 0E34 fault code on Alpha boilers indicates that the central heating system pressure has dropped below the minimum… Read more →
- 0E37 The 0E37 (also displayed as E37) fault code causes a full safety lockout on Alpha boilers — the boiler will stop firing… Read more →
- 0E45 The 0E45 code (sometimes displayed simply as E45) means the boiler has detected a 'High Delta T' — that is, an… Read more →
- 0E46 The Alpha 0E46 code — also displayed as E46 on some models — points to a system pressure sensor error. The boiler's… Read more →
- 0E81 The code '0E81' does not appear in any official Alpha boiler fault code documentation. It is almost certainly a display… Read more →
- 0E98 The 0E98 (also displayed as E98) fault code on Alpha boilers indicates a Hardware Error 3 — a critical internal fault… Read more →
- 0E99 The code '0E99' is not listed in Alpha's standard published fault code tables for any of its current or recent model… Read more →
- FE94 On Alpha boilers, the code E94 — which often appears on the display as FE94 or F.E94, where the 'F' prefix simply… Read more →
- FE95 The code displayed as FE95 on Alpha boilers does not appear in any publicly documented Alpha fault-code list. Alpha… Read more →
- FE96 The FE96 (also displayed as E96) is a safety lockout on Alpha boilers triggered when the boiler's control system… Read more →
- FE97 The Alpha FE97 code — most likely a display variant of the E96 or E97 fault family — indicates that the boiler has… Read more →
Flashing-light patterns (CB range)
- All Lights Flashing On Alpha boilers, a flashing-lights pattern is the primary way the controls communicate a fault rather than displaying… Read more →
- No Lights When your Alpha boiler shows absolutely no lights on its display or control panel, the boiler has lost its electrical… Read more →
- Red A and B Flashing The Red A and B indicator lights on Alpha boilers use their flash pattern to communicate three distinct fault… Read more →
- Red A and B Illuminated When both the A and B indicator lights on your Alpha boiler are illuminated continuously in solid red, the boiler is… Read more →
- Red A Red B Alternating When the A and B indicator lights on your Alpha boiler flash alternately — each one lighting up in turn — the boiler is… Read more →
- Red A Yellow B Flashing On older Alpha boilers that use LED indicator lights instead of a digital display, the Red A and Yellow B lights… Read more →