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Heat pumps · Error codes

ESP heat pump error codes

ESP (Earth Save Products) · A niche brand in the UK. 25 codes across 2 product families, each taken from the manufacturer’s manuals. ESP technical support ↗

Find a ESP engineer →25 codes · reviewed 23 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.

25 codes

CodeMeaningStops?Homeowner check?
1
Cooling water freezing (Cooling water temp. too low)
YesYes
2
Cooling water anti freezing failure (Cooling water temp. after tube inlet too low)
YesYes
3
Low pressure (Low pressure switch action)
YesYes
4
Compressor exhaust temp too high (Compressor exhaust temp too high)
YesYes
5
Over-current on compressor (Current through compressor too high)
YesYes
6
High pressure (High pressure switch action)
YesYes
7
Temp. sensor before tube failure (Temp. disengaged sensor or short circuit)
YesYes
8
Tube outlet temp. sensor failure (Temp. disengaged sensor or short circuit)
YesYes
9
Exhaust temp. sensor failure (Temp. disengaged sensor or short circuit)
YesYes
E
Power supply wrong connection (Wrong connection or lack of connection)
YesYes
E01
High pressure protection: Exhaust pressure is too high
Not statedYes
E02
Low pressure protection: Suction pressure is too low
Not statedYes
E03
Water flow: Insufficient water in the system
Not statedYes
E04
Electric Heater overheat protection: Water flow volume insufficient or the water pressure is too low
Not statedYes
E07
Anti freeze protection: Water flow volume insufficient or the water pressure is too low
Not statedYes
E08
Communication failure: Loss of signal from wired controller to controller
Not statedYes
E09
Winter frost protection: Ambient temperature too low
Not statedYes
FlowError
Flow Error: integrated flow switch senses air/insufficient flow and suspends heat pump operation
YesYes
P01
Bottom water temp. sensor failure: Sensor is open or short-circuit
Not statedYes
P02
Top water temp sensor failure: Sensor is open or short-circuit
Not statedYes
P04
Ambient temp sensor failure: Sensor is open or short-circuit
Not statedYes
P05
Coil temp sensor failure: Sensor is open or short-circuit
Not statedYes
P07
Refrigerant absorb sensor failure: Sensor is open or short-circuit
Not statedYes
P09
Anti-freeze temp sensor failure: Sensor is open or short-circuit
Not statedYes
P034
Solar temp sensor failure: Sensor is open or short-circuit
Not statedYes