Fault codes / Truma AquaGo / 12 and 16

Truma AquaGo codes 12 and 16

What it means: Internal control fault.

What to check

Cycle power. If repeated, control board.

Learn the system

• Tank water heaters
• Tankless water heaters
• Water heater gas side

Practice it on a service call

• No hot water on electric
• Water heater lights, then goes out
• Water heater lights then faults

Guided diagnosis

• Water Heater

Other Truma AquaGo codes

• Truma AquaGo code 1 No flame after 3 tries
• Truma AquaGo code 2 Overtemperature switch (EOS or BOS) open
• Truma AquaGo code 3 Exhaust pressure switch
• Truma AquaGo code 4 Water over 185 F (WOS)
• Truma AquaGo code 5 Flame seen at the wrong time
• Truma AquaGo code 6 Safety circuit switch open
• Truma AquaGo code 7 Control board memory fault
• Truma AquaGo code 9 Outlet sensor (WOT) fault
• Truma AquaGo codes 10 and 11 Safety circuit or watchdog fault
• Truma AquaGo code 13 Shut-off valve current over 1000 mA (short)
• Truma AquaGo code 20 Inlet sensor (WIT) fault, or inlet below 14 F
• Truma AquaGo code 21 Circulation sensor (WCT) fault
• Truma AquaGo code 22 Gas valve modulator fault
• Truma AquaGo code 23 Voltage over 16.4 V
• Truma AquaGo code 24 Voltage under 10 V
• Truma AquaGo code 25 Flue fan current fault
• Truma AquaGo code 26 Circulation pump current fault
• Truma AquaGo code 27 Pump running dry
• Truma AquaGo code 28 Low gas pressure
• Truma AquaGo code 29 Too much hot water demand
• Truma AquaGo code 30 Freeze risk below about 27 F
• Truma AquaGo code 31 Decalcification finished
• Truma AquaGo codes 32 and 33 Antifreeze kit current fault

Full field guide: Truma AquaGo tankless water heater

Codes come from the maker manuals and public service sheets. Your model's own chart always wins, and LP and 120 volt work belongs to a qualified technician.