U357B on 2023-2024 Cadillac Lyriq — Manufacturer-specific network code (definition unverified)
1 vehicles · 1 makes
How to diagnose and fix U357B: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Cadillac Lyriq · 2023–2024
GM bulletin 23-NA-124 covers a dead 12V battery, no-start, inoperative passive-key functions and parasitic draw on the 2023 Lyriq when a Serial Data Gateway Module software anomaly keeps activity alive. PIP6021 separately covers 2023-2024 Lyriq discharge only when its complete listed BECM DTC set is present.
Common Symptoms
- Dead or discharged 12V battery
- No start
- Passive key functions unavailable
- Parasitic draw
How to Fix
Have an EV-qualified Cadillac technician reproduce the draw and scan every module. For the 2023 gateway condition, cycle the specified fuse and verify or update the gateway software. Apply PIP6021 only when all listed DTCs are present; otherwise continue normal service-information diagnosis. Accept applicable future OTA updates. Do not disconnect the 12V or high-voltage system from this card.
Sources for this issue (2)
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U357B code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U357B mean?
U357B stands for "Manufacturer-specific network code (definition unverified)." This code appears in real manufacturer service material - it shows up in a General Motors technical service bulletin hosted by NHTSA alongside other U-series codes - but a verified definition could not be established from a reliable source. U-range codes generally indicate a network or module communication fault rather than a mechanical failure. Because the exact meaning is manufacturer-specific, it must be read with a scan tool that supports the vehicle's make, or looked up in the manufacturer's own service information.
What are the most common causes of U357B?
The most common causes of U357B are: Definition not verified - causes cannot be responsibly listed, Requires manufacturer-specific service information or a dealer-level scan tool. The specific cause varies by vehicle.
How much does it cost to fix U357B?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by U357B?
Au7o has documented U357B across 1 vehicle models from 1 manufacturers: Cadillac.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.