myenergi zappi Contactor Fault
Code 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.
Take care
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 this means
Contactor Fault is code 28, and it is the most serious thing the zappi reports about itself. myenergi's wording is unusually explicit about both the failure and the safeguard: the relay inside the zappi has a welded contact, and the secondary relay is open to make sure that the supply to the EV is isolated. A contactor is the heavy switch that connects mains to your car when a charge starts, and it is the component doing the most work in the unit. When one welds shut, it stops being a switch — it becomes a permanent connection, which is precisely what must not exist on an output that a person handles.
What that second sentence tells you is that the zappi is built with two relays in series specifically so that one failing closed does not leave the output live. The unit has detected the weld, held the other relay open, and reported it. That is a well-designed failure and it is the reason this is a code on a screen rather than something worse on a driveway. It also means the situation is contained rather than urgent in the sense of needing to do something tonight. myenergi's published action is the standard one: unplug the EV, press and hold the menu button to reset. Their installation manual, which calls the same display RLY WELDED! and explains that the welded-contact protection is a requirement of the Renault Z.E. Ready and ASEFA EV Ready standards, gives the hold as three seconds and adds the next step: if the fault cannot be reset that way, contact myenergi technical support. So one reset is worth trying, because the detection can in principle fire on a condition that is not a genuine weld.
What it is not worth doing is trying repeatedly. If the code returns, a welded contactor is a hardware failure inside a permanently connected mains enclosure, and replacing it is not owner work under any reading — myenergi require that anyone commissioning, maintaining or servicing the device is suitably qualified, and that the device is always disconnected from the supply before the cover is removed. Two related codes sit near this one and lead to the same call: code 27, self-test failed, where the built-in protection devices could not be tested or failed the test before a charge, and code 26, comms fault, described as an issue with the built-in protection components. All three are the unit reporting its own safety systems.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| A welded relay contact | myenergi’s stated cause. The contactor has fused closed, usually after long service or a high-current event, and can no longer open. | Common |
| Wear from many switching cycles | A contactor switches every time a charge starts and stops, including every schedule and every session the car interrupts. That is a great many operations over a few years. | Common |
| A fault in the protection components | Related codes 26 and 27 cover the built-in protection devices failing their test or failing to communicate. Different code, same class of problem and the same call. | Occasional |
| A transient detection | Worth one reset to rule out. If the code clears and does not return, it was not a weld; if it comes straight back, it was. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£0–£400
Time on site
30 minutes
Free under warranty, which is where many of these fall. Outside warranty, a contactor replacement or a unit swap — worth establishing which before agreeing to anything.
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
- SelfTest FailedGet it checkedCode 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.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
Is it dangerous?
The failure would be, which is why the unit is designed the way it is. myenergi state that when the relay welds, the secondary relay is open to make sure the supply to the EV is isolated. So the charger has already made the output safe and is telling you about it. It needs fixing, but it is not something to panic about overnight.
Can I keep using it if it resets?
Try one reset. If it clears and stays clear over the following days, the detection fired on something transient. If it returns, stop using the charger and get it looked at — a welded contactor does not heal, and the unit is running on its backup safeguard.
Is this repairable or does the unit need replacing?
That is a question for myenergi or the installer rather than something to guess at. A contactor is a replaceable component in principle, but the labour, the warranty position and the age of the unit all bear on it. Quote them the code number when you get in touch, because 28 tells them exactly what to bring.
What about codes 26 and 27?
They are in the same family. Code 27 is a self-test failure, where the built-in protection devices could not be tested or failed the test before a charge, and code 26 is a comms fault with those protection components. Both are the unit reporting its own safety systems, and both lead to the same call.
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.