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Tesla PCS_a090

Charging slowed - Some AC phases not powered Check power source and charging equipment

Common search variants: PCSa090 · PCS-a090 · PCS a090 · Search ignores case and common separators.

DriveNot yet established by verified evidence.
ChargeAC charging is reduced. Tesla documentation states that DC fast charging/Supercharging should still function as expected.
ServiceNot yet established by verified evidence. The alert instructs the user to check the power source and charging equipment; the supplied evidence does not provide a service-escalation threshold.
Confidence95%

Quick answer

PCS_a090 means AC charging has slowed because the onboard charger detected that one or more AC phases are not powered. Tesla documentation states that DC fast charging/Supercharging should still function as expected.

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 PCS_a090 mean?

PCS_a090 means AC charging has slowed because the onboard charger detected that one or more AC phases are not powered. Tesla documentation states that DC fast charging/Supercharging should still function as expected.

2. Technical explanation

This Tesla alert is titled: “Charging slowed - Some AC phases not powered. Check power source and charging equipment.” Verified Tesla owner-manual material submitted to NHTSA states that charging speed has been reduced by a condition affecting the vehicle’s ability to charge with AC power. The onboard charger has detected that one or more AC phases are not powered. The supplied evidence does not establish the specific failed component or whether the condition is in the external power source, charging equipment, or vehicle.

3. What system is affected?

AC charging system, including the vehicle’s onboard charger and the connected AC power source/charging equipment.

4. How serious is this code?

Unknown. The supplied verified evidence establishes reduced AC charging speed but does not assign a severity level.

5. Symptoms you may notice

  • Reduced AC charging speed.
  • Alert message: “Charging slowed - Some AC phases not powered. Check power source and charging equipment.”
  • DC fast charging/Supercharging should still function as expected, according to the cited Tesla documentation.

6. Possible causes

  • One or more AC phases are not powered, as detected by the vehicle’s onboard charger.
  • The supplied evidence directs the user to check the power source and charging equipment.
  • A more specific cause is not yet established by verified evidence.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

AC charging is reduced. Tesla documentation states that DC fast charging/Supercharging should still function as expected.

9. What you can safely do

  • Check the AC power source and charging equipment, as directed by the alert.
  • For Mobile Connector or Wall Connector status-light troubleshooting, refer to the applicable product Owner’s Manual at Tesla Charging & Adapter Product Guides.
  • Use a Supercharger or Destination Charging location if appropriate; Tesla documentation states that DC fast charging/Supercharging should still function as expected.

10. Step-by-step troubleshooting

  1. Confirm the alert is PCS_a090 and note that AC charging speed is reduced.
  2. Check the power source and charging equipment, following the alert direction.
  3. If using a Tesla Mobile Connector or Wall Connector, consult its product Owner’s Manual for status-light troubleshooting.
  4. Do not attempt high-voltage diagnosis or repair. Specific electrical tests and component-level procedures are not established by the supplied verified evidence.

11. When to contact service

Not yet established by verified evidence. The alert instructs the user to check the power source and charging equipment; the supplied evidence does not provide a service-escalation threshold.

12. What the service center may check

  • Verify the AC power source and charging equipment condition. Further service checks are 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 communication MC-10250484-9999 (Tesla owner-manual material, published 2023-12-01): https://static.nhtsa.gov/odi/tsbs/2023/MC-10250484-9999.pdf
  • NHTSA manufacturer communication MC-10253666-9999 (Tesla owner-manual material, published 2024-03-27): https://static.nhtsa.gov/odi/tsbs/2024/MC-10253666-9999.pdf

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Verified NHTSA-hosted Tesla manufacturer communications describe PCS_a090 as an AC-charging reduction caused by one or more unpowered AC phases and state that DC fast charging/Supercharging should still function as expected. The supplied evidence applies in the US to Tesla Model 3 (2013-2024 across overlapping records), Model S (2012-2024 across overlapping records), Model X (2016-2024 across overlapping records), and Model Y (2020-2024 across overlapping records).

19. Frequently asked questions

What does Tesla PCS_a090 mean?

It means AC charging has slowed because the onboard charger detected that one or more AC phases are not powered.

Can I still use Supercharging with PCS_a090?

Tesla documentation states that DC fast charging/Supercharging should still function as expected.

What should I check first?

The alert directs you to check the power source and charging equipment. For Tesla Mobile Connector or Wall Connector status lights, consult that product’s Owner’s Manual.

Does PCS_a090 identify the failed part?

No. The supplied verified evidence does not identify a specific failed component.

20. Sources & verification

Accepted ResearchVerified
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Tesla PCS_a090: Charging slowed - Some AC phases not powered Check… | EV Diagnostics