BYD Atto 3 1st generation airbag control unit repair

What is a BYD Atto 3 1st generation airbag control unit?

The airbag control unit in the BYD Atto 3 1st generation is the central control unit of the restraint system (SRS). It evaluates the signals from the crash sensors and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners to deploy.

The control unit is fitted in the BYD Atto 3 1st generation (since 2022). It monitors the system continuously. It reports faults via the airbag warning light.

After an accident it stores crash data and locks itself.

The control unit works together with sensors, squib circuits and the vehicle electrical system. It continuously checks whether all connected components are responding and whether the power supply is correct.

Why is the BYD Atto 3 1st generation airbag control unit defective?

The most common cause in the BYD Atto 3 1st generation is crash data stored after an accident, even if no airbag deployed. Other causes are aged electronic components, cold solder joints, moisture and corrosion on connectors, and voltage spikes, for example from a weak battery or jump-starting.

Stored crash data cannot be cleared with an ordinary diagnostic tool. The control unit then remains faulty.

A permanently lit airbag warning light is typical. Often the fault memory cannot be cleared. Sometimes the diagnostic tool cannot establish a connection.

A faulty control unit and a deployed airbag are not the same thing. The control unit can fail even without an accident, for example through ageing of the components or through moisture. Only the inspection shows which cause applies.

Common error codes for BYD Atto 3 1st generation airbag control unit repair

The error codes in the BYD Atto 3 1st generation show what type of fault is present: communication, internal control unit fault, power supply, squib circuit or crash data.

These codes are known for this vehicle:

• B16AE00 → General fault in the SRS control unit
• B17A000 → Internal control unit fault
• B17A200 → Crash data recording locked
• B17A600 → Frontal impact detected by the control unit
• B17A800 → CAN bus communication interrupted
• B1694 → Supply voltage too low
• B1695 → Supply voltage too high
• B1600 → Driver front airbag not connected

Error codes are read out with a diagnostic tool. A code alone does not reliably show that the control unit is defective, as connectors, wiring or an airbag module can also be the cause. Only the inspection clarifies it.

Make a note of the codes or save the read-out log and enclose it with the unit. This makes it quicker to narrow down the fault during the inspection.

What part numbers are available for the BYD Atto 3 1st generation airbag control unit repair?

The part number is on the label of the control unit in the BYD Atto 3 1st generation and determines the exact version, because within a model series there are different numbers depending on equipment and year of manufacture.

The following list contains known part numbers for this vehicle; it makes no claim to completeness:

• SC2EM3658100A

Compare the number on your own unit with this list. This only ensures that it is the right unit. Whether it is defective is shown only by reading out the fault memory or by the inspection.

This is how you get to the repair: first have the fault memory read out and disconnect the battery. Then remove the control unit, create a repair order online and send in the unit. Processing at Airbag24, with checking, repairing and testing, usually takes 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.