Solar · Error codes · Sunsynk
W04Sunsynk · ECCO single-phase hybrid SG05LP1
W04 on a Sunsynk ECCO single-phase hybrid SG05LP1: Meter communication failure
Short answer
On a Sunsynk inverter, W04 means: Meter communication failure. The inverter keeps running.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Meter communication failure.
Part involved: meter.
When it shows: No meter data.
Likely causes:
- Incorrect connection; configuration mismatch; network issues; meter or inverter malfunction.
Is it safe?
| Does the inverter stop? | No |
|---|---|
| Severity | Warning |
The inverter keeps running.
Resetting itself: yes.
Manual reset: Fix wiring/config.
What you can check
- Read the full code and message on the inverter screen or in the Sunsynk Connect app and note the date/time for your installer.
- Check the inverter's AC isolator next to the inverter and the solar/battery breaker in the consumer unit are ON (do not reset a breaker that trips again - call your installer).
What the engineer will check
- Check meter wiring and configuration.
Who to ask for: Qualified electrician / MCS PV installer.
Certification: Battery and hybrid-inverter DC work: installer trained/approved by the manufacturer; electrical work under BS 7671 by a competent person.
What you might notice
Sources
- Fault Codes Causes & Solutions Version 1.0 ↗ · Version 1.0 · page 2 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026