- Vehicles
- Cars
Wall plug temperature high
Tesla UMC_a008 on Model 3: wall plug too hot while charging
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
UMC_a008 and UMC_a017 mean the Mobile Connector detected the wall outlet getting too warm and stopped or slowed charging to protect it. Make sure the adapter is fully plugged in and, if it continues, have an electrician inspect the outlet and its wiring.
Safety first
Stop and check this first
- The alert exists to protect an outlet that is heating up: if it returns with the adapter fully inserted, stop charging from that outlet until an electrician checks it.
Safe checks you can perform
- Charging stopped or only slowed
- Adapter fully inserted
- Outlet inspection by an electrician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Outlet and wiring inspection by an electrician
- Do not attempt this professional task: Stored codes behind the UMC_a008 alert
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Outlet and wiring inspection by an electrician
What they doWith power off, the electrician removes the outlet, checks terminal tightness and the condition of terminals and building wiring, measures temperature or voltage drop under load and replaces the outlet if worn.
They must show youthe condition of the terminals and the removed outlet if it is replaced.
In writingwhich connection was repaired or which outlet was fitted and what charging current it is suitable for.
Stored codes behind the UMC_a008 alert
What they doAt a workshop with EV-trained technicians, they connect a Tesla-capable diagnostic tool and read the stored and pending codes from the Mobile Connector and onboard charger, with the time and conditions in which the UMC_a008 alert was logged, before clearing anything.
They must show youthe code list with status, read while the UMC_a008 alert is active or freshly logged.
In writingthe codes read, the system they point to and which test confirms the fault before any part is replaced for the UMC_a008 alert.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Charging stopped or only slowed
- Who:
- you, on the screen or app.
- How:
- check whether the alert is UMC_a008 (unable to charge) or UMC_a017 (charge rate reduced).
- Result that matters:
- whether charging stopped or continues more slowly.
- If it is UMC_a008:
- charging stopped to protect the outlet; do not keep retrying on that outlet before checking the adapter.
- If it is UMC_a017:
- charging continues more slowly because of the same heating; treat it the same, not as a minor notice.
- Evidence to keep:
- screenshot of the alert with its code.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
Adapter fully inserted
- Who:
- you, without tools.
- How:
- with charging stopped, check the Mobile Connector adapter goes fully into the outlet and try again.
- Result that matters:
- whether charging speed returns to normal.
- If it returns to normal:
- the plug was not fully in; watch the next charges.
- If the alert continues:
- Tesla says to have an electrician inspect the outlet and its wiring.
- Evidence to keep:
- note of the charge after reinserting the adapter.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
Outlet inspection by an electrician
- Who:
- a qualified electrician, not you.
- How:
- inspect the outlet and the building wiring connections to it and complete any repairs needed.
- Result that matters:
- whether there is a loose connection or a worn outlet.
- If the outlet is worn:
- replace it with a high-quality outlet, as Tesla advises.
- If everything is fine:
- ask them to assess whether the circuit suits the charging current.
- Evidence to keep:
- the electrician's report or invoice.
Removing the outlet or touching the wiring is mains-voltage work: qualified electrician only.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- Tesla
- Product type
- Cars
Known code variants
- Charge rate reduced - Wall plug temperature high
- Imposible cargar, enchufe pared muy caliente
- Revise toma de pared y cableado
- Tesla conector móvil enchufe caliente
- Tesla Mobile Connector plug hot
- UMC_a008
- UMC_a017
- Unable to charge - Wall plug temperature high
- Veloc. carga reducida, enchufe pared caliente
- Wall outlet and wiring inspection recommended
What it means
The Tesla Mobile Connector measures temperature at the wall plug. If it gets too high it stops charging (a008) or slows it (a017). Tesla says this does not indicate a problem with the Mobile Connector or the car, but with the outlet or installation: a plug not fully inserted, a loose building wiring connection to the outlet, or an outlet beginning to wear out. The alert protects the outlet; it does not prove which connection is at fault, that is for the electrician to find.
Warnings and stop conditions
- Higheditorial warning
The alert exists to protect an outlet that is heating up: if it returns with the adapter fully inserted, stop charging from that outlet until an electrician checks it.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
Symptoms and causes
Probable causes · in order
- Plug or adapter not fully insertedCommon
This is the first thing Tesla asks you to check. It is recognised because it clears when the adapter is pushed fully into the outlet.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
- Loose wiring connection to the outletPossible
If the adapter is fully in and the alert continues, Tesla points to a loose connection between the building wiring and the outlet.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
- Worn outletPossible
An outlet beginning to wear out heats up at charging current; Tesla says to replace it with a high-quality outlet.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts · Tesla Model 3 manual del propietario: solución de problemas relacionados con alertas
Virtual technician
Does Wall plug temperature high still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
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