Cadillac U197A
Ethernet Time Synchronization Signal Invalid (set by B174W ). − U0499 – Invalid Data Received from Telematics Control Platform Module (se
Quick answer
For applicable 2024–2025 Cadillac LYRIQ vehicles in the US, U197A is identified in GM/NHTSA manufacturer communications as “Ethernet Time Synchronization Signal Invalid,” set by B174W. The supplied evidence does not establish drivability, charging impact, severity, or a specific repair.
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 U197A mean?
For applicable 2024–2025 Cadillac LYRIQ vehicles in the US, U197A is identified in GM/NHTSA manufacturer communications as “Ethernet Time Synchronization Signal Invalid,” set by B174W. The supplied evidence does not establish drivability, charging impact, severity, or a specific repair.
2. Technical explanation
U197A is a network/communication diagnostic trouble code. The verified manufacturer-communication evidence identifies it as an invalid Ethernet time-synchronization signal and states that it is set by B174W. The supplied summaries also list U197A among DTCs that may be Active or History. No further diagnostic criteria, fault path, or component-level cause is established by the supplied evidence.
3. What system is affected?
Ethernet time synchronization / vehicle communications. B174W is identified by the verified evidence as the module setting U197A; its component description is not established by the supplied evidence.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
- U197A may be stored as an Active or History DTC, according to the cited manufacturer communications.
- Driver-observable symptoms are not yet established by verified evidence.
6. Possible causes
- An invalid Ethernet time-synchronization signal reported by B174W.
- Any underlying cause beyond the reported invalid signal 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?
Not yet established by verified evidence.
9. What you can safely do
- Record whether U197A is reported as Active or History.
- Have a Cadillac/GM-qualified service facility evaluate the vehicle using applicable manufacturer diagnostic information.
- Do not attempt high-voltage or module repair procedures based on this page; no such procedure is supported by the supplied evidence.
10. Step-by-step troubleshooting
- Confirm the DTC and whether it is Active or History.
- Review applicable GM manufacturer communication PIT6503E and its earlier listed revisions with a qualified service facility.
- Further troubleshooting steps are not yet established by verified evidence.
11. When to contact service
Service need is not yet established by verified evidence. If U197A is present, a Cadillac/GM-qualified service facility can evaluate it using the applicable manufacturer communication and vehicle diagnostic information.
12. What the service center may check
- Verify whether U197A is Active or History.
- Review whether related communication DTCs are also present, including U1615, U1616, and U0499, as listed in the cited manufacturer communications.
- Additional service checks are not yet established by verified evidence.
13. Possible repair or resolution
- A specific repair or resolution is not yet established by verified evidence.
14. Affected vehicles
- Cadillac LYRIQ · 2024–2025 · US
15. Related TSBs / service bulletins
- GM manufacturer communication PIT6503E, published through NHTSA on August 27, 2026: https://static.nhtsa.gov/odi/tsbs/2026/MC-11036709-0001.pdf
- GM manufacturer communication PIT6503D, published through NHTSA on August 21, 2026: https://static.nhtsa.gov/odi/tsbs/2026/MC-11036400-0001.pdf
- GM manufacturer communication PIT6503C, published through NHTSA on August 12, 2026: https://static.nhtsa.gov/odi/tsbs/2026/MC-11036219-0001.pdf
16. Recall information
- No recall information was supplied in the verified evidence.
17. Official manufacturer information
Verified applicability: 2024–2025 Cadillac LYRIQ, US. Verified sources are NHTSA-hosted GM manufacturer communications PIT6503C, PIT6503D, and PIT6503E. These communications list U197A as “Ethernet Time Synchronization Signal Invalid (set by B174W).”
19. Frequently asked questions
What does U197A mean on an applicable Cadillac LYRIQ?
The verified manufacturer-communication evidence identifies U197A as “Ethernet Time Synchronization Signal Invalid,” set by B174W.
Can U197A be a history code?
Yes. The supplied manufacturer-communication summaries state that U197A may be set as Active or History.
Is it safe to drive or charge with U197A?
Not yet established by verified evidence.
Which vehicles are covered by the supplied evidence?
The supplied applicability record identifies US-market 2024–2025 Cadillac LYRIQ vehicles.