FlowMax FLOWMAX-90 Error Codes

Updated October 13, 2026 · by Aurora Star Tech Inc.

FlowMax FLOWMAX-90 error codes and diagnostic codes. The FLOWMAX-90 is a FlowMax combi boiler in the FlowMax condensing combi (FLOWMAX-90/120) series.

Homeowner with a combi boiler problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

FlowMax FLOWMAX-90 error codes list

Code	Meaning	Severity
31	Incompatible remote control	Low
E01	Ignition / ionization lockout (no flame)	High
E02	Safety (overheat) thermostat or air pressure switch tripped	High
E03	Flue gas thermostat / exhaust thermofuse tripped	High
E05	Heating (supply) sensor fault	Medium
E06	Domestic hot water (DHW) sensor fault	Medium
E12	DHW storage tank (cylinder) sensor fault	Medium
E14	Air pressure switch tripped	High
E16	Fan (blower) fault	High
E22	Parameter programming request	Medium
E35	Flame detection fault (false flame)	High
E42	Fan speed control board fault	High
H2O	Low water pressure in heating circuit	Medium

FlowMax FLOWMAX-90 specs and setup data

Installation clearances FlowMax · Combi Boiler · FlowMax condensing combi (FLOWMAX-90/120)
Hot water scald risk by temperature FlowMax · Combi Boiler · FlowMax condensing combi (FLOWMAX-90/120)

All FlowMax Combi Boiler error codes →

Homeowner help: Tankless Water Heater No Hot Water: What to Check · Boiler Not Heating: What to Check

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

FlowMax FLOWMAX-90 error codes list

FlowMax FLOWMAX-90 specs and setup data

Experience an Energy-Efficient Thermostat in Ajax Today