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Tesla UMC_a015

Wall plug adapter error - Charge rate reduced Plug adapter fully into Mobile Connector and retry

Common search variants: UMCa015 · UMC-a015 · UMC a015 · Search ignores case and common separators.

DriveNot yet established by verified evidence. The supplied information addresses charging through the Mobile Connector, not vehicle drivability.
ChargeCharging may continue with charge current automatically reduced to 8A when this alert is present. The diagnostic record otherwise lists charging status as unknown.
ServiceNot yet established by verified evidence whether Tesla service is required for this alert. Seek Tesla support if the alert persists after fully seating the adapter or if further assistance is needed.
Confidence95%

Quick answer

UMC_a015 means the Tesla Mobile Connector cannot communicate with its wall plug adapter. Charging current is automatically reduced to 8A. Tesla’s stated action is to fully plug the adapter into the Mobile Connector and retry.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does UMC_a015 mean?

UMC_a015 means the Tesla Mobile Connector cannot communicate with its wall plug adapter. Charging current is automatically reduced to 8A. Tesla’s stated action is to fully plug the adapter into the Mobile Connector and retry.

2. Technical explanation

This is a Tesla OEM alert for the Mobile Connector and wall plug adapter connection. When the Mobile Connector cannot identify the type of wall outlet through the adapter, it reduces charge current to 8A. The verified source instruction is: fully plug the wall plug adapter into the Mobile Connector and retry. The provided evidence does not establish an underlying component failure beyond the reported communication error.

3. What system is affected?

Tesla Mobile Connector and its wall plug adapter.

4. How serious is this code?

Unknown. The diagnostic record lists severity as unknown.

5. Symptoms you may notice

  • Tesla displays UMC_a015: “Wall plug adapter error - Charge rate reduced.”
  • The Mobile Connector is unable to communicate with the wall plug adapter.
  • Charge current is automatically reduced to 8A.

6. Possible causes

  • The Mobile Connector is unable to communicate with the wall plug adapter.
  • Not yet established by verified evidence whether the condition is caused by a damaged adapter, Mobile Connector fault, outlet issue, or another condition.

7. Can I still drive the vehicle?

Not yet established by verified evidence. The supplied information addresses charging through the Mobile Connector, not vehicle drivability.

8. Can I charge the vehicle?

Charging may continue with charge current automatically reduced to 8A when this alert is present. The diagnostic record otherwise lists charging status as unknown.

9. What you can safely do

  • Fully plug the wall plug adapter into the Mobile Connector and retry, as instructed in the verified Tesla/NHTSA material.
  • For additional Mobile Connector status-light and charging troubleshooting, refer to the applicable product owner’s manual.
  • Tesla owner-manual material referenced in the verified evidence identifies Tesla Supercharger and Destination Charging locations as charging alternatives.
  • Do not attempt internal repair or disassembly of the Mobile Connector, adapter, outlet, or vehicle charging equipment.

10. Step-by-step troubleshooting

  1. Fully seat the wall plug adapter in the Mobile Connector, then retry charging.
  2. Consult the applicable Mobile Connector/product owner’s manual for status-light and charging-issue troubleshooting.
  3. Not yet established by verified evidence what additional owner-performed diagnostic steps are appropriate if the alert remains.

11. When to contact service

Not yet established by verified evidence whether Tesla service is required for this alert. Seek Tesla support if the alert persists after fully seating the adapter or if further assistance is needed.

12. What the service center may check

  • Not yet established by verified evidence.

13. Possible repair or resolution

  • Fully plugging the wall plug adapter into the Mobile Connector and retrying is the only verified corrective action in the supplied evidence.
  • Not yet established by verified evidence whether replacement or repair of any component resolves a persistent alert.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA manufacturer communication MC-10250484 (published 2023-12-01): https://static.nhtsa.gov/odi/tsbs/2023/MC-10250484-9999.pdf
  • NHTSA manufacturer communication MC-10253666 (published 2024-03-27): https://static.nhtsa.gov/odi/tsbs/2024/MC-10253666-9999.pdf
  • The supplied official NHTSA-hosted Tesla materials describe UMC_a015 and direct the user to fully plug in the adapter and retry.

16. Recall information

  • Not yet established by verified evidence. No recall information was supplied.

17. Official manufacturer information

Verified NHTSA-hosted Tesla owner-manual/manufacturer communications state that UMC_a015 occurs when the Mobile Connector cannot communicate with the wall plug adapter; because the outlet type cannot be identified, charging current is automatically reduced to 8A. Official material: https://static.nhtsa.gov/odi/tsbs/2023/MC-10250484-9999.pdf

19. Frequently asked questions

What does Tesla alert UMC_a015 mean?

It means the Mobile Connector is unable to communicate with the wall plug adapter. The charge rate is reduced.

Why is charging limited to 8A?

Tesla’s supplied material says the Mobile Connector cannot identify the type of wall outlet connected through the adapter, so it automatically reduces charge current to 8A.

What should I do first?

Fully plug the wall plug adapter into the Mobile Connector and retry.

Can I still drive?

Not yet established by verified evidence. The supplied evidence concerns Mobile Connector charging only.

Does this alert require service?

Not yet established by verified evidence. The supplied material provides the adapter-seating action but does not establish when service is required.

20. Sources & verification

Accepted ResearchVerified
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Tesla UMC_a015: Wall plug adapter error - Charge rate reduced Plug… | EV Diagnostics