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Ford P0A77

board diagnostic module C (SOBDMC) or secondary on-board diagnostic module B (SOBDMB)

DriveUnknown. Whether the vehicle can be driven with P0A77 is not established by verified evidence.
ChargeUnknown. Whether the vehicle can be charged with P0A77 is not established by verified evidence.
ServiceContact a Ford dealer or qualified service provider for diagnosis. The supplied evidence does not state whether service is immediately required.
Confidence95%

Quick answer

Ford DTC P0A77 identifies the secondary on-board diagnostic module C (SOBDMC) or secondary on-board diagnostic module B (SOBDMB). Verified evidence links it to Ford Escape and Mustang Mach-E vehicles for model years 2020–2021 in the US.

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 P0A77 mean?

Ford DTC P0A77 identifies the secondary on-board diagnostic module C (SOBDMC) or secondary on-board diagnostic module B (SOBDMB). Verified evidence links it to Ford Escape and Mustang Mach-E vehicles for model years 2020–2021 in the US.

2. Technical explanation

NHTSA manufacturer communication 10201604 (SSM 50151), published September 24, 2021, lists P0A77 among DTCs that may be set by the SOBDMC or SOBDMB. The supplied evidence does not establish a specific component failure, diagnostic procedure, or repair for P0A77.

3. What system is affected?

Secondary on-board diagnostic module C (SOBDMC) or secondary on-board diagnostic module B (SOBDMB).

4. How serious is this code?

Unknown. Severity is not established by the verified evidence.

5. Symptoms you may notice

  • Not yet established by verified evidence.

6. Possible causes

  • Not yet established by verified evidence.

7. Can I still drive the vehicle?

Unknown. Whether the vehicle can be driven with P0A77 is not established by verified evidence.

8. Can I charge the vehicle?

Unknown. Whether the vehicle can be charged with P0A77 is not established by verified evidence.

9. What you can safely do

  • Arrange professional diagnosis using Ford service information.
  • Do not attempt high-voltage system repair based on this code alone.

10. Step-by-step troubleshooting

  1. Confirm the stored DTC with a suitable diagnostic scan tool.
  2. Have a qualified Ford service provider diagnose the vehicle. Further troubleshooting steps are not established by the verified evidence.

11. When to contact service

Contact a Ford dealer or qualified service provider for diagnosis. The supplied evidence does not state whether service is immediately required.

12. What the service center may check

  • Confirm whether P0A77 is stored by SOBDMC or SOBDMB.
  • Check for additional stored DTCs. The official communication lists P0A23, P0A6F, P0A72, P0A75, P0A71, P0A74, P0DFA, P06B1, P0A47, and P1A0E alongside P0A77.
  • Specific test procedures and acceptance criteria are not established by the supplied verified evidence.

13. Possible repair or resolution

  • Not yet established by verified evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA Manufacturer Communication 10201604: SSM 50151, published 2021-09-24. It lists P0A77 as a DTC that may be set by SOBDMC or SOBDMB.
  • Official source: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2020-2024.zip#nhtsa_id=10201604

16. Recall information

  • No recall information was supplied in the verified evidence.

17. Official manufacturer information

Verified source: NHTSA Manufacturer Communication 10201604, SSM 50151 (Ford), published September 24, 2021. Applicability supplied: 2020–2021 Ford Escape and 2020–2021 Ford Mustang Mach-E, US.

19. Frequently asked questions

What does Ford P0A77 mean?

It identifies the secondary on-board diagnostic module C (SOBDMC) or secondary on-board diagnostic module B (SOBDMB).

Which vehicles are covered by the supplied evidence?

US-market 2020–2021 Ford Escape and 2020–2021 Ford Mustang Mach-E vehicles.

Can I drive or charge with P0A77?

Not yet established by verified evidence.

Does SSM 50151 provide a repair for P0A77?

The supplied evidence does not establish a repair procedure or repair resolution.

20. Sources & verification

ReferenceVerified
Ford P0A77: board diagnostic module C (SOBDMC) or secondary on-board… | EV Diagnostics