- Heat pumps
- Air-to-water heat pump
E2-01
Daikin Altherma 4 H F E2-01: leakage current detection error
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Daikin Altherma 4 H F error E2-01 means the outdoor unit leakage current PCB detected current leakage on the unit power supply line and stopped the heat pump (reset: power cycle). Do not touch the outdoor unit or cycle breakers to clear it; call a qualified electrician or installer.
Safety first
Stop and check this first
- Note that in the production brief check 2 falsely called E2-01 an automatic reset code; Daikin's table actually marks E2-01 as a Power cycle reset, and you must never repeatedly flip breakers or reset the unit before an electrician resolves the leakage fault.
- Danger of electrocution: E2-01 means current leakage was detected on the unit power supply line. Never touch the outdoor unit or electrical components with wet hands, never remove the switch box cover yourself, and remember that internal capacitors remain hazardous until power has been disconnected for more than 10 minutes and measured below 50 V DC.
Safe checks you can perform
- Visually check the 30 mA earth leakage circuit breaker (Q1DI) in the household electrical panel
- Check [11] Malfunctioning and [11] Malfunction history for companion code E2-06
- Do not power-cycle the circuit breakers yourself to clear E2-01
Leave these tasks to a qualified professional
- Do not attempt this professional task: Isolate power for over 10 minutes, verify <50 V DC, and measure outdoor unit insulation resistance
- Do not attempt this professional task: Verify dedicated circuit, earthing continuity, and inverter-compatible 30 mA RCD (Q1DI)
- Do not attempt this professional task: Inspect leakage current PCB A3P and perform controlled power-cycle reset
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Isolate power for over 10 minutes, verify <50 V DC, and measure outdoor unit insulation resistance
What they doAn authorised electrician or certified Daikin technician turns off all power supplies, waits more than 10 minutes, verifies that main circuit capacitor voltage is less than 50 V DC before touching electrical parts, and measures insulation resistance on the outdoor unit power supply line and components per the service manual.
They must show youthe multimeter reading below 50 V DC before servicing and the insulation resistance readings in megaohms for each tested circuit.
In writingthe insulation resistance values measured on the supply line and outdoor components, the faulty component or cable identified, and the repair completed.
Verify dedicated circuit, earthing continuity, and inverter-compatible 30 mA RCD (Q1DI)
What they doThe authorised electrician verifies that the heat pump runs on a dedicated power circuit, that earth wiring is properly connected (not to a utility pipe, surge absorber, or telephone earth), that switch box terminals are tight, and that field breaker Q1DI is a 30 mA inverter-compatible earth leakage protector.
They must show youthe earth continuity measurement and the specification label of the 30 mA inverter-compatible earth leakage circuit breaker Q1DI.
In writingthe earthing resistance/continuity result, the Q1DI breaker model and rating, and confirmation that all switch box terminals are securely connected.
Inspect leakage current PCB A3P and perform controlled power-cycle reset
What they doAfter correcting the insulation or wiring fault (or verifying per the service manual whether board A3P is defective when no leakage is present), the technician closes all covers, performs the required power-cycle reset, and runs heating and hot water to confirm E2-01 does not return.
They must show youthe indoor user interface home screen and [11] Malfunctioning free of E2-01 during live compressor operation.
In writingany replaced part reference (including A3P if applicable), the post-repair insulation reading, and the test run timestamp.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Visually check the 30 mA earth leakage circuit breaker (Q1DI) in the household electrical panel
- Who:
- You, looking at the household distribution board without opening any panel cover or touching wiring.
- How:
- Check whether the field earth leakage circuit breaker (Q1DI, 30 mA) or dedicated circuit breaker feeding the heat pump has tripped to the OFF position.
- Result that matters:
- Knowing whether the building's 30 mA earth leakage breaker also tripped alongside board A3P's E2-01 detection.
- If the earth leakage circuit breaker Q1DI has tripped OFF, that confirms current leakage to earth exceeded the building protection threshold and indicates you must leave it OFF until an authorised electrician tests insulation.
- If Q1DI remains ON while E2-01 is active on the indoor screen, that indicates the outdoor unit's A3P leakage current PCB stopped the unit first and you should still leave all breakers untouched.
- Evidence to keep:
- Take a photo of the electrical distribution board showing the position of the heat pump circuit breakers.
Never touch electrical components with wet hands, never open the switch box cover, and do not re-close a tripped earth leakage breaker before an electrician locates the earth fault.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C · Daikin Altherma 4 H F+W+ECH2O operation manual 4PEN773378-1C
Check [11] Malfunctioning and [11] Malfunction history for companion code E2-06
- Who:
- You, using the indoor unit user interface touchscreen.
- How:
- Go to [11] Malfunctioning, tap E2-01 to display its long description, and check [11] Malfunction history (with advanced end user permission) to see whether E2-06 appears alongside E2-01.
- Result that matters:
- Daikin's error table lists E2-06 immediately after E2-01 under the same title (Leakage current detection error) with the trigger Electric leakage missing-core error.
- If E2-06 is logged together with E2-01, that points to the leakage detection core or A3P board wiring inside the outdoor unit.
- If E2-01 appears alone without E2-06, that keeps the primary focus on active current leakage along the outdoor unit power supply line and load components.
- Evidence to keep:
- Save a photo of the [11] Malfunctioning long description and the timestamped list in [11] Malfunction history.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C · Daikin Altherma 4 H F+W+ECH2O operation manual 4PEN773378-1C
Do not power-cycle the circuit breakers yourself to clear E2-01
- Who:
- You, without touching the unit disconnects or outdoor unit casing.
- How:
- Even though the chapter 14 table lists Power cycle as the reset method for E2-01, leave the power cycle to the technician after insulation testing; note from [6.2] Dealer information who to call and check [5.23] Emergency selection if indoor heating is needed.
- Result that matters:
- Daikin warns not to turn off the circuit breakers after commissioning and states in section 14.4 that it is important to understand the problem and take measures before resetting an error code.
- If a power cycle was already attempted and E2-01 returned immediately, that confirms a standing earth leakage fault is present on the outdoor unit supply line.
- If no power cycle has been performed, that prevents re-energising a live earth fault before an electrician measures insulation resistance.
- Evidence to keep:
- Write down whether any power outage or breaker reset occurred before or after E2-01 appeared.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C · Daikin Altherma 4 H F+W+ECH2O operation manual 4PEN773378-1C
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- Daikin
- Product type
- Air-to-water heat pump
Known code variants
- Altherma 4 H F E2-01
- code erreur Daikin Altherma E2-01
- codice E2-01 pompa di calore Daikin
- código E2-01 bomba de calor Daikin
- Daikin Altherma error E2-01
- Daikin Altherma Fehler E2-01
- Daikin E2-01
- Daikin heat pump code E2-01
- Daikin Wärmepumpe Fehlercode E2-01
- défaut E2-01 pompe à chaleur Daikin
- error Daikin Altherma E2-01
- errore Daikin Altherma E2-01
What it means
In chapter 14.4.4 of the Daikin Altherma 4 H F installer reference guide (4PEN773391-1C, page 205), code E2-01 is titled Leakage current detection error, triggered when the leakage current PCB detects current leakage on the power supply line of the unit. The heat pump stops operating and the reset column specifies Power cycle. In the section 16.5 outdoor wiring legend, board A3P is the dedicated printed circuit board (leakage current) and Q1DI is the 30 mA field earth leakage circuit breaker. Code E2-01 confirms earth leakage detection on the supply path, but by itself does not prove which cable segment or outdoor component is leaking current.
Warnings and stop conditions
- Mediumeditorial warning
Note that in the production brief check 2 falsely called E2-01 an automatic reset code; Daikin's table actually marks E2-01 as a Power cycle reset, and you must never repeatedly flip breakers or reset the unit before an electrician resolves the leakage fault.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C · Daikin Altherma 4 H F+W+ECH2O operation manual 4PEN773378-1C
- Highsource verified
Danger of electrocution: E2-01 means current leakage was detected on the unit power supply line. Never touch the outdoor unit or electrical components with wet hands, never remove the switch box cover yourself, and remember that internal capacitors remain hazardous until power has been disconnected for more than 10 minutes and measured below 50 V DC.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C · Daikin Altherma 4 H F+W+ECH2O operation manual 4PEN773378-1C
Symptoms and causes
Probable causes · in order
- Insulation breakdown or current leakage to earth in the outdoor unit or power supply lineCommon
Board A3P (printed circuit board for leakage current) monitors the outdoor unit supply line and stops the heat pump with E2-01 when current leaks to earth, which may also trip the 30 mA earth leakage circuit breaker Q1DI.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- Field electrical wiring, earthing, or non-inverter-compatible earth leakage protector issuePossible
Section 2.1.5 requires a dedicated power circuit, proper earth wiring (never earthed to a utility pipe, surge absorber, or telephone earth), and an inverter-compatible earth leakage protector resistant to high-frequency electrical noise.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- Missing-core or sensing fault on the A3P leakage current detection circuitLess common
If insulation resistance and earthing pass all checks, a sensing fault on board A3P or its core assembly (related to adjacent code E2-06, Electric leakage missing-core error) can trigger a leakage current detection lockout.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Virtual technician
Does E2-01 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Daikin Europe N.V. · 2026 · official_doc
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