B17A800 - CAN communication interrupted airbag control unit fault

What does error code B17A800 mean in the airbag control unit?

Error code B17A800 indicates that communication over the vehicle's CAN bus has been interrupted, meaning the connection to the data bus is missing. The airbag control unit stores this fault and switches on the airbag warning light straight away, so the failure is clearly visible to the driver.

The data connection of the airbag control unit via the CAN bus is therefore affected. The code thus describes a fault in communication, not an impact.

The code does not state which device on the data bus is affected.

How do you recognise error code B17A800?

You recognise error code B17A800 by the permanently lit airbag warning light and by an entry in the fault memory of the airbag control unit. The entry cannot be permanently erased, and a diagnostic tool may in some cases be unable to reach the control unit in the vehicle via the data bus.

The code is read out with a diagnostic tool. If the control unit cannot be reached, this points to the interrupted communication.

What causes error code B17A800?

Error code B17A800 occurs when communication over the CAN bus is interrupted and the airbag control unit no longer has a connection to the data bus. The possible causes are the control unit itself, a disturbed power supply, and the data line with its connector; the test shows which of these applies.

• The control unit does not respond because it is defective or locked
• The power supply to the control unit is disturbed
• The data line is interrupted or damaged
• The connector on the data line is damaged

The code alone does not say which of these points is affected. The check at a specialist workshop answers this question.

In which vehicles does error code B17A800 occur?

On BYD vehicles, error code B17A800 is known, among others, on the Atto 2, Atto 3, Dolphin, Seal, Seal 6 and Sealion 7 models. The list given here is not complete, and the meaning may differ on other vehicles.

Models such as the Han, Tang, Seal U and e6 are also among the known vehicles. Whether a specific vehicle is affected is checked by reading out the fault memory with a diagnostic tool.

How is error code B17A800 resolved?

Error code B17A800 is resolved by reading out the fault memory and then having the connectors and lines checked at a specialist workshop. If the cause lies in the control unit itself, it is removed after the battery has been disconnected and sent in for testing and repair.

First have the fault memory read out with a diagnostic tool, then have the connectors and data lines checked at a specialist workshop. Safety note: work on the airbag system should be left to qualified professionals.

If the control unit is considered the cause, first disconnect the battery and only then remove the control unit. Then create a repair order online and send the unit in. Checking, repairing and testing usually take 3–4 working days.

The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.