- Heat pumps
- Air-to-water heat pump
L8-01
Daikin Altherma 4 H F L8-01: Malfunction triggered by a thermal protection in the inverter PCB
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
L8-01 means “Malfunction triggered by a thermal protection in the inverter PCB” on the scoped Altherma 4 H F family. Daikin records this trigger: Malfunction by thermal protection inverter PCB: Electronic thermal 1. Effect: Heat pump will stop operating. The table marks the reset as manual.
Safety first
Stop and check this first
- Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Safe checks you can perform
- Preserve the diagnostic state
- Use the displayed reset path once
- Isolate abnormal electrical symptoms
Leave these tasks to a qualified professional
- Do not attempt this professional task: Measured handoff for L8-01
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.
Measured handoff for L8-01
What they doGive the technician L8-01, both model numbers, the source trigger “Malfunction by thermal protection inverter PCB: Electronic thermal 1”, the effect “Heat pump will stop operating”, reset result and recurrence conditions. They should follow Daikin's power and electrical protection branch and compare live measurements with the service values before replacing parts.
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.
Preserve the diagnostic state
Photograph L8-01 and the complete display. Record both unit model numbers, operating mode, requested temperatures, weather, system pressure shown to the user and the moment the code appeared.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Use the displayed reset path once
Daikin marks this code as manual reset. Only when the installation is safe, follow the reset instruction shown by the user interface or the exact user manual once. Do not enter maintenance mode; recurrence ends user troubleshooting.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Isolate abnormal electrical symptoms
Leave the system off after burning smell, heat, noise, sparking or repeated protective trips. Do not open electrical panels, test terminals or repeatedly re-energize the unit.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
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 L8-01
- code erreur Daikin Altherma L8-01
- codice L8-01 pompa di calore Daikin
- código L8-01 bomba de calor Daikin
- Daikin Altherma error L8-01
- Daikin Altherma Fehler L8-01
- Daikin heat pump code L8-01
- Daikin L8-01
- Daikin Wärmepumpe Fehlercode L8-01
- défaut L8-01 pompe à chaleur Daikin
- error Daikin Altherma L8-01
- errore Daikin Altherma L8-01
What it means
In guide 4P773391-1C (2026.02), Daikin assigns L8-01 to “Malfunction triggered by a thermal protection in the inverter PCB”. The documented trigger is “Malfunction by thermal protection inverter PCB: Electronic thermal 1” and the operating effect is “Heat pump will stop operating”. This is a precise controller decision for Daikin Altherma 4 H F — EPSK(S)04~14A + EPVX07~14S18+23A; it does not by itself prove which component failed.
Warnings and stop conditions
- Highsource verified
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Symptoms and causes
Probable causes · in order
- What the controller establishedConfirmed
Daikin's table defines the condition as “Malfunction triggered by a thermal protection in the inverter PCB” and gives this exact trigger: Malfunction by thermal protection inverter PCB: Electronic thermal 1.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- What the unit does nextConfirmed
Documented effect: Heat pump will stop operating. Reset classification: Manual. A cleared display is not proof of repair.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Virtual technician
Does L8-01 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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