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Tesla CC_a021

Unable to charge - No primary Wall Connector Check that primary unit is powered and available

Common search variants: CCa021 · CC-a021 · CC a021 · Search ignores case and common separators.

DriveNot yet established by verified evidence.
ChargeCharging through the affected Wall Connector load-sharing network is unavailable. Whether charging is available by another method is not yet established by verified evidence.
ServiceContact a qualified electrician for load-sharing configuration and power availability checks. If the issue persists after those checks, obtain Wall Connector service.
Confidence95%

Quick answer

CC_a021 means the Tesla cannot charge because a Wall Connector load-sharing network has no available primary Wall Connector. The verified guidance is to have an electrician confirm that exactly one Wall Connector is configured as primary and that it is powered and available. If the issue continues, the Wall Connector requires service.

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1. What does CC_a021 mean?

CC_a021 means the Tesla cannot charge because a Wall Connector load-sharing network has no available primary Wall Connector. The verified guidance is to have an electrician confirm that exactly one Wall Connector is configured as primary and that it is powered and available. If the issue continues, the Wall Connector requires service.

2. Technical explanation

Verified Tesla/NHTSA documentation describes CC_a021 as a load-sharing (circuit-breaker-sharing) network condition: one, and only one, Wall Connector must be configured as the primary unit. The alert indicates that the primary unit is not available. The supplied evidence does not establish a vehicle high-voltage battery fault or an onboard charging fault.

3. What system is affected?

Tesla Wall Connector load-sharing (circuit-breaker-sharing) network, specifically the required primary Wall Connector.

4. How serious is this code?

The diagnostic severity is not yet established by verified evidence. The alert prevents the described Wall Connector charging arrangement from charging.

5. Symptoms you may notice

  • The vehicle displays: “Unable to charge - No primary Wall Connector. Check that primary unit is powered and available.”
  • Charging is unavailable through the affected Wall Connector load-sharing network.

6. Possible causes

  • No Wall Connector in the load-sharing network is configured as the primary unit.
  • The configured primary Wall Connector is not powered or not available.
  • More than one Wall Connector may be configured as primary; verified guidance states that only one may be primary.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Charging through the affected Wall Connector load-sharing network is unavailable. Whether charging is available by another method is not yet established by verified evidence.

9. What you can safely do

  • Have a qualified electrician assess the Wall Connector load-sharing configuration.
  • After the electrician completes applicable work and restores power to the Wall Connector, reconnect the Wall Connector to the vehicle and try charging again.
  • If the issue persists, arrange Wall Connector service.
  • Refer to the installation guide for the applicable Wall Connector.

10. Step-by-step troubleshooting

  1. Have an electrician confirm that exactly one Wall Connector in the load-sharing network is set as the primary configuration.
  2. Have the electrician confirm that the primary Wall Connector is powered and available.
  3. After power has been restored following applicable electrical work, reconnect the Wall Connector to the vehicle and retry charging.
  4. If CC_a021 remains, the verified documentation states that the Wall Connector requires service.

11. When to contact service

Contact a qualified electrician for load-sharing configuration and power availability checks. If the issue persists after those checks, obtain Wall Connector service.

12. What the service center may check

  • Confirm one, and only one, Wall Connector is set as the primary unit in the load-sharing network.
  • Confirm the primary Wall Connector is powered and available.
  • If the alert persists after configuration and power restoration, service the Wall Connector.

13. Possible repair or resolution

  • Correct the load-sharing configuration so exactly one Wall Connector is configured as primary.
  • Restore availability of the primary Wall Connector as applicable.
  • If the issue continues, service the Wall Connector.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Official NHTSA manufacturer communication/owner documentation records CC_a021 and its load-sharing guidance, including NHTSA document MC-10250484 (published December 1, 2023): https://static.nhtsa.gov/odi/tsbs/2023/MC-10250484-9999.pdf
  • Additional official NHTSA manufacturer communication record: MC-10253666 (published March 27, 2024): https://static.nhtsa.gov/odi/tsbs/2024/MC-10253666-9999.pdf

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

The verified official sources are NHTSA-hosted Tesla manufacturer communications/owner documentation. They state that a load-sharing network needs one, and only one, primary Wall Connector; an electrician should confirm the configuration and availability of that unit. Source: https://static.nhtsa.gov/odi/tsbs/2023/MC-10250484-9999.pdf

19. Frequently asked questions

What does Tesla alert CC_a021 mean?

It means the Wall Connector load-sharing network has no available primary Wall Connector. Verified guidance says this network requires one, and only one, Wall Connector configured as primary.

What should be checked for CC_a021?

A qualified electrician should confirm that exactly one Wall Connector is configured as primary and that the primary unit is powered and available.

What if the alert remains after the configuration and power checks?

The verified documentation states that the Wall Connector requires service.

Can I still drive with CC_a021?

Not yet established by verified evidence.

20. Sources & verification

Accepted ResearchVerified
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Tesla CC_a021: Unable to charge - No primary Wall Connector Check that… | EV Diagnostics