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Tesla UMC_a005

Unable to charge with Mobile Connector Voltage too low / Try a different wall outlet

Common search variants: UMCa005 · UMC-a005 · UMC a005 · Search ignores case and common separators.

DriveNot yet established by verified evidence.
ChargeCharging with the Mobile Connector may not start or may be interrupted while this alert is present. Tesla directs the user to try a different wall outlet.
ServiceNot yet established by verified evidence.
Confidence95%

Quick answer

Tesla alert UMC_a005 means charging cannot begin or is interrupted because the Mobile Connector detects insufficient supply voltage from the wall outlet or an unexpected voltage drop. Tesla’s documented action is to try a different wall outlet.

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1. What does UMC_a005 mean?

Tesla alert UMC_a005 means charging cannot begin or is interrupted because the Mobile Connector detects insufficient supply voltage from the wall outlet or an unexpected voltage drop. Tesla’s documented action is to try a different wall outlet.

2. Technical explanation

This is a Mobile Connector supply-voltage alert, not a verified diagnosis of an internal vehicle fault. The documented condition is that the Mobile Connector either does not detect enough voltage at the wall outlet or detects an unexpected drop in that voltage during charging.

3. What system is affected?

Tesla Mobile Connector and its wall-outlet supply connection.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • The vehicle cannot charge.
  • Charging is interrupted.
  • The vehicle displays UMC_a005: “Unable to charge with Mobile Connector Voltage too low / Try a different wall outlet.”

6. Possible causes

  • The Mobile Connector does not detect enough supply voltage from the wall outlet.
  • The Mobile Connector detects an unexpected drop in supply voltage from the wall outlet.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Charging with the Mobile Connector may not start or may be interrupted while this alert is present. Tesla directs the user to try a different wall outlet.

9. What you can safely do

  • Try a different wall outlet, as directed in the Tesla documentation.
  • Refer to the product owner’s manual for Mobile Connector status-light and charging-issue troubleshooting.
  • Tesla documentation identifies Tesla Supercharger and Destination Charging locations as alternative charging locations, which can be located using the vehicle touchscreen map.

10. Step-by-step troubleshooting

  1. Try charging from a different wall outlet.
  2. Consult the applicable product owner’s manual for Mobile Connector status lights and charging issues.

11. When to contact service

Not yet established by verified evidence.

12. What the service center may check

  • Not yet established by verified evidence.

13. Possible repair or resolution

  • Not yet established by verified evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA manufacturer communications/owner-documentation records include UMC_a005 and describe the alert as insufficient or unexpectedly dropping wall-outlet supply voltage. Examples: MC-10253666-9999 (published 2024-03-27), MC-10250484-9999 (published 2023-12-01), and MC-10240947-9999 (published 2023-06-09).

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Verified official NHTSA-hosted Tesla documentation: https://static.nhtsa.gov/odi/tsbs/2024/MC-10253666-9999.pdf

19. Frequently asked questions

What does Tesla UMC_a005 mean?

It means the vehicle cannot charge, or charging is interrupted, because the Mobile Connector detects insufficient supply voltage from the wall outlet or an unexpected drop in supply voltage.

What should I do when UMC_a005 appears?

Try a different wall outlet. Tesla also directs users to the product owner’s manual for Mobile Connector status-light and charging-issue troubleshooting.

Does UMC_a005 confirm that the vehicle has an internal charging fault?

No. The verified documentation identifies a Mobile Connector wall-outlet supply-voltage condition; it does not establish an internal vehicle fault.

20. Sources & verification

Accepted ResearchVerified
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Tesla UMC_a005: Unable to charge with Mobile Connector Voltage too low… | EV Diagnostics