In brief

Fault code E0 on Mitsubishi Electric Ecodan ATW Databook (PUZ WZ) Vol.1 .0 — ecodan-atw-databook- means: Fault code E0 indicates a signal transmission or reception anomaly between the remote controller(s) and the interface unit/flow temperature controller (FTC) of the outdoor unit, specifically when communication fails for 3 minutes for the main controller or 2 minutes for a secondary controller. Most common cause: The main cause is a communication failure due to a faulty connection, incorrect wiring, excessive cable length (max 500m), electromagnetic interference (noise), or the absence of a main controller configuration when multiple remote controllers are connected. First action: Inspect the transmission cable and interface unit/FTC connections for any disconnection or looseness.. Call a registered engineer if the fault returns after basic checks or involves refrigerant work (F-Gas registered engineer required).

According to Mitsubishi Electric documentation, fault code E0 is triggered if the main controller does not receive data for 3 minutes or if a secondary controller is deprived of it for 2 minutes.

E0 • Mitsubishi Electric • Ecodan ATW Databook (PUZ WZ) Vol.1 .0 — ecodan-atw-databook-

Fault code E0 Mitsubishi Electric: causes, diagnosis and solution

Fault code E0 indicates a signal transmission or reception anomaly between the remote controller(s) and the interface unit/flow temperature controller (FTC) of the outdoor unit, specifically when communication fails for 3 minutes for the main controller or 2 minutes for a secondary controller.

Source: Mitsubishi Electric documentation (service manual – according to product reference) · Updated on 16 June 2026

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What does fault code E0 on Mitsubishi Electric mean?

The main cause is a communication failure due to a faulty connection, incorrect wiring, excessive cable length (max 500m), electromagnetic interference (noise), or the absence of a main controller configuration when multiple remote controllers are connected.

Symptômes

Display of fault code E0 on the remote controller(s).
Illumination of LEDs (LED1, LED2) on the outdoor unit board indicating fault code E4.
Loss of communication between the main controller and the interface unit/FTC.
Loss of communication between secondary controllers and the network.
Display of associated codes such as 'RC NG', 'RC E3' or 'ERC 00-66' during diagnosis.

Diagnostic

1. Physical and wiring check

Inspect the transmission cable and interface unit/FTC connections for any disconnection or looseness.
Check the total cable length (max 500m) and ensure no triple cable is used.
Confirm that at least one remote controller is configured as 'main'.

2. Remote controller diagnosis

Perform remote controller diagnosis: if 'RC OK' is displayed, the problem lies elsewhere.
If 'RC NG' is displayed, replace the faulty remote controller.
If 'RC E3' or 'ERC 00-66' is displayed, suspect noise on the transmission cable.

How to reset fault code E0 on Mitsubishi Electric?

After checking and correcting the physical connections and remote controller configuration, restart the unit. If the problem persists and the diagnosis indicates 'RC OK', replace the interface unit/FTC board. If the diagnosis indicates 'RC NG', replace the affected remote controller.

When should you call an F-Gas engineer?

This code appears during a loss of bidirectional communication in the remote controller network. It is common after wiring manipulation, network extension beyond specified limits, or in the case of noise on the line. The installer must check the 'Main/Sub' configuration and

Affected models

Ecodan ATW Databook (PUZ WZ)
Ecodan ATW PUHZ W50VHA BS
Ecodan PUHZ SW50VKA BS
Ecodan PUHZ HW140VHA2 BS

Field context

Technical source data

Fault code E0 signals a signal transmission or reception error between the remote controllers and the interface unit/flow temperature controller (FTC) of the outdoor unit. The anomaly is triggered if the main controller does not receive data for 3 minutes or if a secondary controller is deprived of it for 2 minutes. Causes include faulty connections, incorrect wiring, excessive cable length (max 500 m), absence of a main controller configuration, or electromagnetic interference. The final diagnosis via the 'RC' code determines whether the remote controller or the FTC board should be replaced. (Sources: Extract 1, Extract 2, Extract 4)

Sources: Ecodan ATW PUHZ W50VHA BS Service — ecodan-atw-puhz-w50vha-bs-service.pdf (p. 20) · Ecodan PUHZ SW50VKA BS Service Manual OCH525C — ecodan-puhz-sw50vka-bs-service-manual-och525c.pdf (p. 26) · Ecodan ATW Databook (PUZ WZ) Vol.1 .0 — ecodan-atw-databook-puz-wz-vol-1-0.pdf (p. 128)

Questions fréquentes

What are the exact non-reception times that trigger fault code E0?

Fault code E0 is displayed if the main controller receives no transmission from the interface unit for 3 minutes, or if a secondary controller receives no signal for 2 minutes. These times vary depending on the controller's role in the network.

How do I diagnose whether the fault is from the remote controller or the FTC board?

After checking the wiring and configuration, perform a diagnosis. If the display shows 'RC OK', the remote controllers are healthy; replace the FTC board if the problem persists. If the display shows 'RC NG', replace the affected remote controller.

What are the wiring constraints to avoid this code?

The total cable length must not exceed 500 metres. It is imperative not to use more than two cables in parallel (cable x 3 or more). Additionally, ensure at least one remote controller is configured as 'main' if multiple units are connected.

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