Ford P27B4
board diagnostic control module C (SOBDMC) or the charge status indicator (CSI) is blinking red with DTC P0A7F s
Quick answer
For 2021–2022 Ford Mustang Mach-E vehicles in the US, DTC P27B4 is verified as a Ford diagnostic code title associated with the secondary on-board diagnostic control module C (SOBDMC). Verified Ford/NHTSA evidence also describes a red-triangle condition with P27B4 stored in the SOBDMC, and a blinking-red Charge Status Indicator (CSI) condition with DTC P0A7F in related TSB evidence.
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 P27B4 mean?
For 2021–2022 Ford Mustang Mach-E vehicles in the US, DTC P27B4 is verified as a Ford diagnostic code title associated with the secondary on-board diagnostic control module C (SOBDMC). Verified Ford/NHTSA evidence also describes a red-triangle condition with P27B4 stored in the SOBDMC, and a blinking-red Charge Status Indicator (CSI) condition with DTC P0A7F in related TSB evidence.
2. Technical explanation
The supplied record defines P27B4 as: “board diagnostic control module C (SOBDMC) or the charge status indicator (CSI) is blinking red with DTC P0A7F s.” The official NHTSA-hosted Ford communication for TSB 25-2343 states that a vehicle may exhibit an illuminated red triangle with P27B4 stored in the secondary on-board diagnostic module C (SOBDMC), or a blinking-red CSI with P0A7F stored. The supplied excerpts do not establish the underlying fault mechanism, root cause, diagnostic procedure, or repair.
3. What system is affected?
Secondary on-board diagnostic control module C (SOBDMC) and Charge Status Indicator (CSI), as identified in the supplied Ford/NHTSA evidence.
4. How serious is this code?
Unknown. The verified diagnostic record lists severity as unknown.
5. Symptoms you may notice
- An illuminated red triangle with DTC P27B4 stored in the SOBDMC is described in the NHTSA-hosted Ford TSB 25-2343 evidence summary.
- A blinking-red Charge Status Indicator (CSI) with DTC P0A7F stored is described in the same evidence summary.
6. Possible causes
- Not yet established by verified evidence.
7. Can I still drive the vehicle?
Unknown. The verified diagnostic record lists safe-to-drive status as unknown.
8. Can I charge the vehicle?
Unknown. The verified diagnostic record lists safe-to-charge status as unknown.
9. What you can safely do
- Do not attempt high-voltage diagnosis or repair.
- Record any warning indicators and the DTCs retrieved from the vehicle.
- Arrange Ford service evaluation because the verified evidence identifies SOBDMC/CSI diagnostic conditions but does not provide a user-performed resolution.
10. Step-by-step troubleshooting
- Check for stored diagnostic codes using appropriate diagnostic equipment.
- Confirm whether P27B4 is stored in the secondary on-board diagnostic control module C (SOBDMC).
- Confirm whether the Charge Status Indicator is blinking red and whether P0A7F is stored.
- Further troubleshooting steps are not yet established by the supplied verified evidence.
11. When to contact service
Ford service evaluation is appropriate if P27B4 is present, a red triangle is illuminated, or the CSI is blinking red. The supplied evidence does not establish a specific urgency level or repair procedure.
12. What the service center may check
- Retrieve and document DTCs, including P27B4 and P0A7F where present.
- Identify whether P27B4 is stored in the SOBDMC.
- Verify the reported red-triangle and/or blinking-red CSI condition.
- Consult applicable Ford service information, including the referenced Ford TSBs, for model- and vehicle-specific procedures.
13. Possible repair or resolution
- Not yet established by verified evidence.
14. Affected vehicles
- Ford Mustang Mach-E · 2021–2022 · US
15. Related TSBs / service bulletins
- Ford TSB 25-2343, published July 25, 2025, is referenced by NHTSA Manufacturer Communication 11020978. Its supplied evidence summary describes an illuminated red triangle with P27B4 stored in the SOBDMC, or a blinking-red CSI with P0A7F stored.
- Ford TSB 22-2491, published December 16, 2022, is referenced by NHTSA Manufacturer Communication 10228802. The supplied excerpt specifically concerns 2022 e-Transit vehicles built on or before September 17, 2022; applicability of this bulletin to Mustang Mach-E is not established by the supplied evidence.
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Verified source: NHTSA Manufacturer Communication 11020978, Ford TSB 25-2343: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2025-2026.zip#nhtsa_id=11020978
19. Frequently asked questions
What does P27B4 mean?
The supplied Ford diagnostic record defines it as a condition involving the secondary on-board diagnostic control module C (SOBDMC) or a blinking-red Charge Status Indicator (CSI) with DTC P0A7F.
Which vehicles are verified as applicable?
The supplied applicability record identifies US-market 2021–2022 Ford Mustang Mach-E vehicles.
What warning may appear with P27B4?
The supplied official Ford/NHTSA evidence describes an illuminated red triangle with P27B4 stored in the SOBDMC.
Is P0A7F related?
The supplied evidence describes a blinking-red CSI with P0A7F stored. It does not establish a technical causal relationship between P27B4 and P0A7F.
Can I drive or charge the vehicle?
Not yet established by verified evidence. Both safe-to-drive and safe-to-charge status are recorded as unknown.