The Complete Guide To JFY Inverter Error Codes

Why a JFY error code is worth sorting now

A JFY Suntwins with an E code on its screen is not exporting. On every sunny day it stays that way, you buy back from the grid the power your panels should have covered. E01 and E02 need more care than the rest: they mean the inverter has found weak insulation or current leaking to earth on the solar side.

JFY is defunct in Australia, and there is no warranty or parts for these inverters. The units still running went in between 2010 and 2015, so an E04 or E06 on one of them usually means a board or relay at the end of its life, and a replacement. Some JFY messages have nothing to do with the inverter. W01 can be a blackout or a tripped switch, and E03 is the grid moving outside its limits for a moment.

Sorting it early keeps the choice yours. If the unit is finished, the panels usually stay and a hybrid in its place leaves room for a battery. If a damp connector is behind an E01, fixing it now stops it tripping the system again with the next rain.

Find your code in the table below to see what it means and how urgent it is. If your home is in Adelaide, the Adelaide Hills, Gawler, the Barossa, the Fleurieu, Murray Bridge and Yorke Peninsula in South Australia, or North Brisbane, Caboolture, Bribie Island, the Sunshine Coast, Noosa and Gympie in Queensland, our own licensed electricians will go through it with you over the phone for free before anyone drives out. Check your postcode to see if we cover you.

Which JFY inverter do you have?

Look for the label on the side of the inverter. JFY units usually say Suntwins, with a model number ending in TL.

Suntwins TL series: the JFY range covered by the 2013 operator's manual, which every code on this page is read from.
JFY Tech: the company name you may see on the label or paperwork. The same inverters and the same position: defunct in Australia, with no parts.

All 18 JFY error codes, explained

A JFY Suntwins shows a fault as a code on its screen with the manual's short name beside it, like E01 Isolation Error. E01 to E14 are errors, W01 and W02 are warnings. All 18 are in one table below. The number in brackets after each code's name is its source in the reference list.

Stop and call A safety or hardware fault that nobody can fix from a phone. Do the one safe restart at most, then call.
Worth a look Something to check or restart safely. If it comes back, book a visit.
Wait and watch The inverter has paused for a reason outside itself, usually the grid or the light, and restarts on its own.

We always err on the cautious side: when a code sits between two ratings, it gets the higher one.

14 stop and call, 2 worth a look, 2 wait and watch.

Error code	What it means	What to do
Auto Test FailedJFY Auto Test Failed	Grid protection self-test failed^[1] The inverter ran its built-in grid protection test and did not pass. It will not export until the test passes, which needs an electrician to re-run it and find out why it failed. A failed self-test means the inverter cannot prove its own protection works, so we treat it as a call. Safe steps in the lookup	Stop and call
E01JFY E01	Panel insulation fault^[1] The inverter found too little insulation between the panel wiring and earth, usually water in a connector or isolator, a chafed cable or a damaged panel. It is a safety trip and needs an electrician to find the fault. Safe steps in the lookup	Stop and call
E02JFY E02	Earth leakage fault^[1] The inverter measured current leaking to earth from the solar wiring, usually damaged cable insulation or water in a connector, sometimes a fault on the AC side. Because this is an electrical safety trip it needs an electrician. Safe steps in the lookup	Stop and call
E03JFY E03	Grid out of range^[1] The mains voltage or frequency at the inverter went outside its limits for a moment, so it disconnected. It reconnects by itself; if it happens most sunny afternoons the cable run or the street voltage needs checking. Safe steps in the lookup	Wait and watch
E04JFY E04	Internal consistency fault^[1] The inverter's two control circuits are giving readings that do not agree, which the manual lists as an inverter fault. If a restart does not clear it the control board has failed. Safe steps in the lookup	Stop and call
E05JFY E05	Inverter too hot^[1] The inverter's internal temperature is outside its limit, so it stopped. On a unit this age it is usually a tired fan or a heatsink full of dust rather than the weather; the manual lists it as an inverter fault. Heat shutdowns point at a failing fan, a blocked vent or a bad installation spot, so we treat them as a call. Safe steps in the lookup	Stop and call
E06JFY E06	Output relay failure^[1] The relay that connects the inverter to the grid has failed its self-test. The manual lists it as an inverter fault; on a unit this age it usually means the relay or power board has worn out, which is a job for an electrician. Safe steps in the lookup	Stop and call
E07JFY E07	DC injection too high^[1] The inverter is letting too much DC into its AC output, which the grid rules do not allow. The manual lists it as an inverter fault; a restart may clear a one-off, but a repeat means the output stage needs testing. DC on the AC side is a protection fault, so we treat it as a call. Safe steps in the lookup	Stop and call
E08JFY E08	Memory failure^[1] The inverter's settings memory has failed. The manual lists it as an inverter fault; a restart sometimes clears it, otherwise the control board needs repair. Internal and hardware faults need testing with the right instruments, so we treat them as a call. Safe steps in the lookup	Stop and call
E09JFY E09	Internal communication failure^[1] The boards inside the inverter have stopped talking to each other. The manual lists it as an inverter fault; if a restart does not clear it the inverter needs an electrician. Internal and hardware faults need testing with the right instruments, so we treat them as a call. Safe steps in the lookup	Stop and call
E10JFY E10	Internal DC bus overvoltage^[1] The voltage on the inverter's internal DC bus went too high. The manual lists it as an inverter fault; it can follow a string that is too long, but on a unit this age it is usually a failing component inside. Safe steps in the lookup	Stop and call
E11JFY E11	Internal DC bus undervoltage^[1] The voltage on the inverter's internal DC bus is too low. The manual lists it as an inverter fault, which on a unit this age usually means the bus capacitors or power board have failed. Safe steps in the lookup	Stop and call
E12JFY E12	Internal reference voltage fault^[1] The precise reference voltage the inverter's electronics measure everything against has drifted or failed. The manual lists it as an inverter fault; it needs the control board tested. Safe steps in the lookup	Stop and call
E13JFY E13	DC current sensor fault^[1] The sensor that measures the current from the panels has failed. The manual lists it as an inverter fault; it needs the inverter tested by an electrician. Safe steps in the lookup	Stop and call
E14JFY E14	Earth leakage sensor failed^[1] The inverter's own earth-leakage protection device is damaged, as opposed to finding a real leak. Because the inverter can no longer protect against leakage it must stay off until an electrician has looked at it. Safe steps in the lookup	Stop and call
No displayJFY No display	No display or lights^[1] The screen and lights are off. At night or in heavy cloud that is normal, because a Suntwins runs off the panels; in good sun it means no DC is reaching the inverter or the inverter has died. Safe steps in the lookup	Worth a look
W01JFY W01	No grid detected^[1] The inverter cannot see mains power on its AC side. Either the power is out, the solar supply main switch or breaker is off, or an AC connection has failed. Safe steps in the lookup	Wait and watch
W02JFY W02	Panel voltage too high^[1] The voltage from the panels is above what the inverter can accept, usually too many panels in one string, which shows up most on cold clear mornings. The string design needs checking by an electrician. Safe steps in the lookup	Worth a look

Got a JFY error code? Free phone diagnosis in our service area

Our own licensed electricians cover Greater Adelaide and regional SA, and from North Brisbane up through the Sunshine Coast to Gympie. Check your postcode, then read us the code and tell us the install year. If it needs a visit, the callout is credited against the work.

How to reset a JFY inverter safely

Try one restart, in this order:

Switch the solar supply main switch off at the switchboard.
Switch the DC isolator off at the inverter.
Wait five minutes.
Switch the DC isolator back on, then the solar supply main switch.

Never open the unit or touch the wiring. Never restart anything that smells hot or shows scorch marks. If the code comes back after one restart, stop and call.

JFY inverter repair or replacement?

Our electricians test the whole system on a visit, not only the inverter: insulation resistance on every string, earth continuity, the output relay, DC string voltages and currents, the AC supply and the inverter's own readings. An E01 is usually found on the roof, in a wet connector or isolator, a chafed cable or a damaged panel, and that is a repair to the wiring.

An E06 is the relay that connects the inverter to the grid failing its self-test, which on a unit this age usually means the relay or power board has worn out. With no JFY parts, that ends in a replacement. We quote a straight replacement and a hybrid option side by side so a battery can go in now or later. Most of the time the panels stay, and the callout comes off the price of whichever option you take.

We do this work in Adelaide, the Adelaide Hills, Gawler, the Barossa, the Fleurieu, Murray Bridge and Yorke Peninsula in South Australia, or North Brisbane, Caboolture, Bribie Island, the Sunshine Coast, Noosa and Gympie in Queensland only. Outside those areas, everything above still applies: take the code, its meaning and the urgency to a licensed electrician near you.

Where these JFY error codes come from

Every JFY code on this page was read from the maker's own manual. The numbers match the references in the code table.

[1]
JFY Suntwins xxxxTL series Installation and Operator's Manual, Rev 1.2 (2013), archived copy18 codes, from the maker's own document

Tables last updated 21 October 2026

JFY error code questions, answered

How do I read a JFY error code?

Wait for daylight, because a Suntwins runs off its panels and the screen is dark at night. Note the code exactly, the letter and the two digits, then type it into the search box above the table. An E code is an error and the inverter has stopped; a W code is a warning about the grid or the panel voltage.

What does JFY E01 mean?

E01 is “panel insulation fault”. The inverter found too little insulation between the panel wiring and earth, usually water in a connector or isolator, a chafed cable or a damaged panel. It is a safety trip and needs an electrician to find the fault. We rate it stop and call. See it in the table.

What does JFY E06 mean?

E06 is “output relay failure”. The relay that connects the inverter to the grid has failed its self-test. The manual lists it as an inverter fault; on a unit this age it usually means the relay or power board has worn out, which is a job for an electrician. We rate it stop and call. See it in the table.

Do you cover my area?

We work in Adelaide, the Adelaide Hills, Gawler, the Barossa, the Fleurieu, Murray Bridge and Yorke Peninsula in South Australia, or North Brisbane, Caboolture, Bribie Island, the Sunshine Coast, Noosa and Gympie in Queensland. Check your postcode to be sure. Outside those areas, this page still tells you what your code means and how urgent it is, and a licensed electrician near you can take it from there.

What does it cost to have a JFY looked at?

For homes in our service area, the phone diagnosis is free. If it needs a visit, there is a callout fee, and it is credited against any repair or replacement we do.

Will you work on a JFY you did not install?

Yes, if it is in our service area. Most of our repair work is on systems someone else installed. We test the whole system, not just the unit on the wall.

Is JFY the same as Suntwins?

Yes. JFY made the inverters and Suntwins is the range name, so a label may say either or both. The codes on this page apply whichever name is on yours.

Can I keep my panels if my JFY is replaced?

Usually. Our electricians test the strings and their wiring first, and if they pass, the new inverter connects to the panels you already have. If an E01 or E02 brought you here, that same test finds where the fault is, so it does not follow you onto the new inverter.

Where do the codes on this page come from?

All 18 come from JFY’s own Installation and Operator’s Manual for the Suntwins TL series, revision 1.2 from 2013, read from an archived copy. Each code carries a numbered reference to it in the source list.

Written by

Joe Deionno

Started in 2017 after years of subcontracting and seeing the dodgy operators at work; set out to be the installer people could trust. Oversees every install in both states.

Related guides

More solar repairs guides from our electricians.

All solar repairs guides

Swipe to see more

Inverter faults · 5 min read

The Complete Guide To Delta Solivia Inverter Error Codes

All 29 Delta Solivia and RPI error codes in plain English: what each one means, how urgent it is, how to reset your inverter safely, and what your replacement options are now that Delta has left the Australian home market.

Inverter faults · 5 min read

The Complete Guide To Omnik Inverter Error Codes

All 20 Omnik and Trannergy error codes in plain English: what each one means, how urgent it is, how to restart safely, and what your replacement options are now Omnik and its portal are gone.