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Cadillac U1667

voltage battery surge tank and document via photo. 3. Observe and record the Battery Energy Control Module parameter(s); K16– Battery Energy Control Module -> Data Display -> High

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService evaluation is appropriate because the applicable bulletin directs trained technicians to perform the diagnostic process and states that repairs must be performed by technicians who completed required training.
Confidence95%

Quick answer

U1667 is listed in Cadillac/GM Bulletin 23-NA-151 for specified U.S. Cadillac LYRIQ and VISTIQ vehicles. The supplied verified evidence does not establish a standalone code definition, severity, drivability, or charging status.

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 U1667 mean?

U1667 is listed in Cadillac/GM Bulletin 23-NA-151 for specified U.S. Cadillac LYRIQ and VISTIQ vehicles. The supplied verified evidence does not establish a standalone code definition, severity, drivability, or charging status.

2. Technical explanation

The database canonical text for U1667 is a truncated service-procedure fragment rather than a confirmed fault definition. Bulletin 23-NA-151 includes U1667 among DTCs used in a high-voltage battery diagnostic process. The documented process includes visually inspecting and photographing coolant level in the high-voltage battery surge tank and recording Battery Energy Control Module high-voltage-isolation data. The bulletin states that repairs must be performed by a technician who has completed the required training.

3. What system is affected?

High-voltage battery diagnostic process, including the high-voltage battery surge tank and Battery Energy Control Module high-voltage isolation data.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

Not yet established by verified evidence.

6. Possible causes

  • Not yet established by verified evidence. The available bulletin evidence lists U1667 within a diagnostic process but does not identify a standalone root cause for this code.

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

  • Arrange diagnosis by a Cadillac/GM service facility or appropriately trained technician.
  • Do not attempt high-voltage battery repairs yourself.

10. Step-by-step troubleshooting

  1. A trained technician may verify whether U1667 is current, as directed by the applicable version of Bulletin 23-NA-151.
  2. The bulletin procedure includes documenting coolant level in the high-voltage battery surge tank with a photo.
  3. The bulletin procedure includes recording Battery Energy Control Module high-voltage isolation-data parameters.

11. When to contact service

Service evaluation is appropriate because the applicable bulletin directs trained technicians to perform the diagnostic process and states that repairs must be performed by technicians who completed required training.

12. What the service center may check

  • Confirm DTC status using the applicable revision of GM Bulletin 23-NA-151.
  • Inspect and document coolant level in the high-voltage battery surge tank.
  • Record K16 Battery Energy Control Module high-voltage isolation data, including the most recent isolation-resistance information where applicable.
  • Use the complete bulletin procedure to determine next steps; the supplied evidence does not establish a specific repair for U1667 alone.

13. Possible repair or resolution

  • Not yet established by verified evidence. No specific U1667 repair or resolution is provided in the supplied evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • GM/Cadillac Bulletin 23-NA-151, published through NHTSA manufacturer communications including MC-10243714 (September 5, 2023), MC-10245234 (October 19, 2023), MC-11002022 (June 5, 2024), MC-11011944 (November 20, 2024), MC-11012693 (December 11, 2024), and MC-11017886 (April 9, 2025). The supplied evidence shows U1667 is included in this bulletin's diagnostic DTC lists.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official source: NHTSA-hosted GM/Cadillac manufacturer communication Bulletin 23-NA-151, including https://static.nhtsa.gov/odi/tsbs/2025/MC-11017886-0001.pdf

19. Frequently asked questions

What does U1667 mean?

Not yet established by verified evidence. The supplied canonical text is a truncated diagnostic-procedure fragment, and the available bulletin excerpts do not provide a standalone definition.

Is U1667 covered by a GM bulletin?

Yes. U1667 is listed in GM/Cadillac Bulletin 23-NA-151 as part of a high-voltage battery diagnostic process.

Can I drive or charge with U1667?

Not yet established by verified evidence. The supplied bulletin excerpts do not provide a drive or charge authorization for U1667.

20. Sources & verification

Verified
Cadillac U1667: voltage battery surge tank and document via photo. 3.… | EV Diagnostics