myenergi zappi SelfTest Failed
Code 27, searched as A27. The built-in protection devices could not be tested, or failed the test, before a charge. myenergi’s action is a reset; they do not say it cannot be repaired.
Take care
What this means
Before every charge the zappi tests its own protection: the residual-current detection and the protective-earth check that stand between the supply and your car. SelfTest Failed, fault code 27, is what it shows when that test could not run or did not pass, and myenergi’s manual gives the meaning in one line: the built-in protection devices couldn’t be tested or failed the test prior to a charge. The action they publish is the same as for most of the numbered codes: unplug the EV, then press and hold the button to reset the unit. The code is often written A27, and the phrase that travels with it online, that a zappi with A27 cannot be repaired, is not myenergi’s.
What myenergi actually say, at the foot of the same table, is that if any of the faults persist you should stop using the zappi and contact your supplier or myenergi technical support. That is a repair route, not a write-off, and code 27 is one of the codes most often cleared by the published reset because the test is sensitive by design.
A single 27 that resets and stays away is the protection being cautious. A 27 that returns on every plug-in means one of the protection components inside the unit is genuinely failing its check, and since those components are what make the charger safe to use, the unit should not be forced past it. Related codes tell you which part: 26 is the same components failing to communicate, 28 is the main relay welded.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| A protection component failed its pre-charge check | myenergi’s stated meaning. The residual-current or earth-check circuit did not return the expected result, and the zappi refuses to start the charge on it. | Common |
| The test could not be completed | The manual gives this as the alternative reading of the same code. A momentary condition on the supply or a car that dropped the connection mid-test leaves the check incomplete; the reset lets it run again. | Common |
| An earthing arrangement the earth test does not suit | The zappi’s earth checks assume a TN or TT supply. myenergi note on the neighbouring PE Fault code that an IT-earthed supply needs the Supply Grid / Earthing setting changed, which is installer work. | Occasional |
| A failing protection module | The 27 that comes back every time. The component under test is wearing out or has a fault, and the manual’s persistence clause applies: stop using it and contact support. | Occasional |
What to try yourself
Unplug the car from the zappi. The reset does not work with the EV connected.
Press and hold the menu button on the zappi — the round button with three lines — until the fault clears from the screen. This is myenergi’s published reset for code 27; the installation manual gives three seconds for the hold.
Plug the car back in and let the zappi run its self-test again. If the charge starts, the test had failed to complete rather than found a fault; make a note of the date in case it recurs.
If 27 returns immediately or on the next few sessions, stop using the charger and contact your installer or myenergi support with the code number and the unit’s serial. Do not open the unit or bypass anything.
The components that failed the test are the ones protecting you from an earth fault at the car. A charger that will not pass its own protection test is not a charger to keep resetting.
Get a registered electrician to look at your myenergi zappi ev charger
We do not pass enquiries to a repair firm, so there is no form here. When you book a registered electrician, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What it costs to fix
Typical repair cost
£0–£400
Time on site
10 minutes
Nothing if the reset clears it, which is common. A persistent 27 is a protection module or a unit exchange: free under myenergi’s warranty, and £150 to £400 including labour outside it depending on what is replaced.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related myenergi zappi fault codes
- Contactor FaultGet it checkedCode 28. myenergi say a relay inside the unit has welded, and that a second relay is holding the supply to your car isolated. Their action is one reset; if it returns, contact them.Related: internal protection
- Comms FaultGet it checkedCode 26: the zappi cannot talk to its own built-in protection components. One reset is the published action; a repeat is a hardware fault inside the unit.Related: internal protection
- Output FaultGet it checkedCode 24: the zappi has measured voltage on its output when the output should have been off. The unit stays off; reset once, and if it repeats it is a call to myenergi.Related: internal protection
- Voltage MismatchGet it checkedCode 32: the zappi’s controller and its protection components measured the output voltage differently. A disagreement between two safety measurements, so the unit stops.Related: internal protection
- PEN FaultStop — call an engineerCode 29. The protection against loss of the supply earth-neutral conductor has operated, and myenergi tell you to remove the fault before resetting.Related: same brand
- PE FaultStop — call an engineerCode 25. myenergi say the earth is either disconnected or its impedance is too high — a problem in the installation rather than in the charger.Related: same brand
Own a myenergi zappi ev charger? Save it and its codes come first next time.
Related guides
Common questions
Does A27 mean the zappi cannot be repaired?
myenergi say nothing of the kind. Their published action is a reset, and if the fault persists, to stop using the unit and contact your supplier or their technical support. Whether a persistent 27 is fixed by replacing a protection module or by exchanging the unit is a decision they or the installer make on the day; the code does not settle it.
Why A27 rather than 27?
The manual prints it as Fault code 27 next to the SelfTest Failed message. The A prefix appears in app notifications and in how owners write it down; it is the same code.
Can I make it charge anyway?
No, and you should not want to. The self-test exists because the zappi switches the protective earth as well as live and neutral to cover a lost PEN conductor, and it needs to know that switching works before it connects your car. A unit that cannot verify that is protecting you by refusing.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.