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BYD U20B300

BIC4 CAN communication timeout

DriveUnknown. Safe-to-drive status is not yet established by verified evidence.
ChargeUnknown. Safe-to-charge status is not yet established by verified evidence.
ServiceService requirement is unknown in the supplied evidence. Contact qualified BYD service personnel for diagnosis, particularly if the code is current or recurring.
Confidence95%

Quick answer

U20B300 is identified in verified BYD diagnostic evidence as “BIC4 CAN communication timeout.” It applies to specified BYD ATTO 3, DOLPHIN, and HAN vehicles listed below. The available evidence does not establish drivability, charging status, symptoms, causes, or repair instructions.

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 U20B300 mean?

U20B300 is identified in verified BYD diagnostic evidence as “BIC4 CAN communication timeout.” It applies to specified BYD ATTO 3, DOLPHIN, and HAN vehicles listed below. The available evidence does not establish drivability, charging status, symptoms, causes, or repair instructions.

2. Technical explanation

This DTC records a CAN communication timeout involving BIC4. Verified evidence establishes the code name and its association with the HV battery/network system, but does not provide diagnostic thresholds, component-location details, test procedures, or a confirmed failure mechanism.

3. What system is affected?

HV battery/network

4. How serious is this code?

Unknown. Severity is 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.

7. Can I still drive the vehicle?

Unknown. Safe-to-drive status is not yet established by verified evidence.

8. Can I charge the vehicle?

Unknown. Safe-to-charge status is not yet established by verified evidence.

9. What you can safely do

  • Do not attempt high-voltage battery or CAN-network repair based on this code alone.
  • Have the vehicle assessed by appropriately qualified BYD service personnel if the DTC is present or recurs.

10. Step-by-step troubleshooting

  1. Use appropriate diagnostic equipment to confirm the stored DTC and document any accompanying codes. Further test steps are not yet established by verified evidence.
  2. Do not perform high-voltage component disassembly or repairs without manufacturer procedures and qualified personnel.

11. When to contact service

Service requirement is unknown in the supplied evidence. Contact qualified BYD service personnel for diagnosis, particularly if the code is current or recurring.

12. What the service center may check

  • Confirm whether U20B300 is stored and whether it is current or historical.
  • Check for accompanying diagnostic codes. No further service checks are established by verified evidence.

13. Possible repair or resolution

  • Not yet established by verified evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • No technical service bulletin information was supplied or established by verified evidence.

16. Recall information

  • No recall information was supplied or established by verified evidence.

17. Official manufacturer information

Verified technical-manual index evidence identifies U20B300 as “BIC4 CAN communication timeout” for the listed BYD applications. Sources: OBDTotal technical manual index, BYD ATTO 3 diagnostic evidence (https://obdtotal.com/product/byd-atto3-yuanplus-sc2e-service-manual/); 17VIN technical manual index, BYD DOLPHIN diagnostic evidence (https://en.17vin.com/automotive_repair_manual_wiring_diagrams/BYD/2123.html); and 17VIN technical manual index, BYD HAN diagnostic evidence (https://en.17vin.com/automotive_repair_manual_wiring_diagrams/BYD/2120.html).

19. Frequently asked questions

What does BYD code U20B300 mean?

Verified evidence identifies U20B300 as “BIC4 CAN communication timeout.”

Which vehicles are covered by the supplied evidence?

BYD ATTO 3, model years 2022–2026, Global; BYD DOLPHIN, model years 2021–2026, Global; and BYD HAN, model year 2023, Global.

Can I drive or charge with U20B300?

Safe-to-drive and safe-to-charge status are not yet established by verified evidence.

20. Sources & verification

Verified
BYD U20B300: BIC4 CAN communication timeout | EV Diagnostics