Cadillac U2BFF
loss of isolation
Quick answer
For a 2023 Cadillac LYRIQ (US), DTC U2BFF means “loss of isolation.” A Cadillac Service Update, N222390690, directs technicians to inspect for a high-voltage harness contacting a metal edge when this code is present.
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 U2BFF mean?
For a 2023 Cadillac LYRIQ (US), DTC U2BFF means “loss of isolation.” A Cadillac Service Update, N222390690, directs technicians to inspect for a high-voltage harness contacting a metal edge when this code is present.
2. Technical explanation
Verified NHTSA-published manufacturer communication 10236077 (Service Update N222390690, published May 11, 2023) instructs technicians to scan for U2BFF. If U2BFF is present, the communication directs them to disable the high-voltage system using Cadillac service information before proceeding with the inspection procedure. The service update concerns a high-voltage harness contacting a metal edge.
3. What system is affected?
High-voltage system / high-voltage harness.
4. How serious is this code?
Not yet established by verified evidence. However, the manufacturer communication requires high-voltage-system disabling when U2BFF is present before the specified service procedure continues.
5. Symptoms you may notice
- DTC U2BFF stored: “loss of isolation.”
6. Possible causes
- For the covered service update, a high-voltage harness contacting a metal edge is the documented inspection concern.
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Do not attempt high-voltage diagnosis, disassembly, or repair yourself.
- Arrange assessment by a qualified Cadillac/GM service facility.
- Tell the service facility that U2BFF is present and ask them to review Service Update N222390690.
10. Step-by-step troubleshooting
- A qualified technician should scan for DTC U2BFF.
- The manufacturer communication states that, if U2BFF is present, the high-voltage system is to be disabled according to Cadillac service information before continuing the procedure.
- The communication then directs inspection of the orange high-voltage cables on the right side of the vehicle as part of Service Update N222390690.
11. When to contact service
Contact a Cadillac dealer or qualified GM EV service facility promptly for diagnosis. Provide DTC U2BFF and request review of NHTSA manufacturer communication 10236077 / Service Update N222390690.
12. What the service center may check
- Confirm whether U2BFF is present.
- Follow the manufacturer-required high-voltage disabling procedure if U2BFF is present.
- Inspect the high-voltage harness/cables for the condition covered by Service Update N222390690: contact with a metal edge.
13. Possible repair or resolution
- Not yet established by verified evidence. The supplied communication establishes an inspection/service-update procedure but does not provide sufficient verified evidence here to state the final repair outcome.
14. Affected vehicles
- Cadillac LYRIQ · 2023 · US
15. Related TSBs / service bulletins
- Cadillac Service Update N222390690, NHTSA Manufacturer Communication PDF 10236077, published May 11, 2023. It addresses a high-voltage harness contacting a metal edge and includes U2BFF (loss of isolation) in its procedure.
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Official source: NHTSA Manufacturer Communication PDF 10236077, Cadillac Service Update N222390690: https://static.nhtsa.gov/odi/tsbs/2023/MC-10236077-0001.pdf
19. Frequently asked questions
What does Cadillac code U2BFF mean?
It means “loss of isolation.”
Which vehicle is supported by the supplied evidence?
The verified applicability is a 2023 Cadillac LYRIQ in the United States.
Is there an official service communication related to U2BFF?
Yes. Cadillac Service Update N222390690, published by NHTSA as manufacturer communication 10236077, includes a procedure to scan for U2BFF and addresses a high-voltage harness contacting a metal edge.
Can I keep driving or charging with U2BFF?
Not yet established by verified evidence.