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Heat pumps · Error codes

Navien heat pump error codes

Navien · A niche brand in the UK. 50 codes across 1 product family, each taken from the manufacturer’s manuals.

Find a Navien engineer →50 codes · reviewed 24 September 2026

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Type the code on your display or a word from its meaning. Each code opens its own page with what it means, whether it is safe and what you can check.

50 codes

CodeMeaningStops?Homeowner check?
E04
Electric heater overheating protection
Not statedYes
E08
Communication failure between the PCB and display
YesYes
E11
HP protection (HP switch is open)
YesYes
E12
LP protection (LP switch is open)
YesYes
E19
Primary antifreeze protection
PartlyYes
E29
Secondary antifreeze protection
PartlyYes
E032
Flow switch protection (flow switch is open)
YesYes
E051
Compressor overcurrent shutdown error
YesYes
E065
High water outlet temp. protection
Not statedYes
E081
Communication failure between PCB and fan driver board
YesYes
E103
Fan motor overload protection
YesYes
E171
Anti-freeze protection
PartlyYes
F01
Compressor activation failure
YesYes
F03
PFC error
YesYes
F05
DC bus overvoltage
YesYes
F06
DC bus undervoltage
YesYes
F07
AC input undervoltage
YesYes
F08
AC input overcurrent
YesYes
F09
Input voltage sampling error
YesYes
F10
Communication failure between DSP and PFC
YesYes
F11
Communication error between DSP and communication board
YesYes
F12
Communication failure between the PCB and driver board
YesYes
F13
IPM overheating stop
YesYes
F15
Input voltage lacking phase
YesYes
F16
Compressor has weak magnetic protection alarm
YesYes
F17
Drive board temperature error
Not statedYes
F18
IPM current sampling error
YesYes
F20
IGBT power device overheating alarm
YesYes
F22
AC input over current protection alarm
YesYes
F23
EEPROM fault alarm
YesYes
F24
Broken EEPROM activation ban alarm
YesYes
F25
LP 15V underload error
YesYes
F26
IGBT power device overheat error
YesYes
F031
DC fan motor 1 failure
YesYes
F032
DC fan motor 2 failure
YesYes
P01
Water inlet temp. sensor error
PartlyYes
P02
Water outlet temp. sensor error
PartlyYes
P04
Ambient temp. sensor error
PartlyYes
P17
Water outlet temp. sensor error (second outlet sensor)
PartlyYes
P032
Hot water tank temp. sensor error
PartlyYes
P42
Room temp. sensor error
PartlyYes
P101
EVI inlet temp. sensor error
PartlyYes
P102
EVI outlet temp. sensor error
PartlyYes
P153
Coil temp. sensor error
PartlyYes
P181
Exhaust temp. sensor error
PartlyYes
P182
Exhaust over temp. (exhaust temp >= C05, default 110 C)
YesYes
P191
Antifreeze temp. sensor error
PartlyYes
Pp1
Exhaust pressure sensor error
PartlyYes
Pp2
Suction pressure sensor error
PartlyYes
TP
Low ambient temp. protection
Not statedYes