U0100 — Lost Communication (BYD Context)
Written and edited by Ethan Cole, Editor-in-Chief · ✓ Technically reviewed by Daniel Wei Chen — Senior Chinese Automotive Diagnostics & Repair Specialist, Sydney · 22 August 2026.
Standard meaning: a control module lost contact with the powertrain computer on the CAN network. On an EV whose every function is a computer conversation, U0100 sounds terminal. The documented order says otherwise: on BYDs, network weirdness is downstream of 12V weakness often enough that voltage is always step one.
What it means on your BYD
| Scenario | Likely story | First move |
|---|---|---|
| After a flat-12V event or jump-start | Modules browned out mid-conversation; codes are the scar tissue. | 12V health, clear once, watch. |
| With screen/audio failures | The documented DiLink/T-Box hang family (Dolphin, Seal, Sealion 7) lives on the same networks. | The 10-second volume-roller reset; then firmware currency. |
| Recurring with drive symptoms | Genuine harness/connector fault. | Service centre — CAN diagnosis on a vehicle full of orange cable is theirs alone. |
Safe owner checks
- 12V health and history — the perennial first answer.
- Which systems complained together, and when? The cluster maps the network segment.
- Firmware current? Australian cars documented lagging other markets — a manual flash request is legitimate.
When it’s a workshop job
Anything recurring or anything with driving symptoms. Never probe connectors or looms on an EV — parts of the network run beside high voltage, and the line between them is not visible from outside the insulation.
Code definition per SAE J2012. Context: our BYD problems research — the 12V-first ordering and the DiLink hang family are documented per model in the extraction records.
Disclaimer: Information on this page is general guidance only and does not replace the manufacturer’s official documentation or the judgement of a qualified technician. Never open, touch or work on any orange high-voltage component. Fault-code behaviour varies between markets, model years and software versions. Last verified: 22 August 2026.