AU
B16AE00

Internal fault in the SRS_ECU (airbag control unit) or systemic power supply/communication fault — Atto 3

Safety System

Internal fault in the SRS_ECU (airbag control unit) or systemic power supply/communication fault.

This DTC indicates the airbag control module detects a functional fault in its processor, memory, power management circuit, or internal communication bus, preventing the system from guaranteeing accurate crash detection and reliable airbag deployment.

Upon triggering, the SRS system enters fail-safe mode, disables all airbag and seat belt pretensioner functions, and continuously illuminates the instrument panel airbag warning light.

The system may fail to provide occupant protection during a collision, and other safety systems may experience limited functionality.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1SRS ECU internal circuit board fault (damaged main control chip, memory, or power management IC, usually due to voltage fluctuations or component aging)
  • 2Abnormal ECU supply voltage (battery voltage below 9V or above 16V, dedicated fuse blown, ground terminals G301/G302 loose, oxidized, or corroded)
  • 3CAN bus communication fault (HS-CAN line short circuit, open circuit, abnormal terminating resistor, or electromagnetic interference interrupting communication between the ECU and vehicle network)
  • 4Abnormal collision sensor circuit impedance (short circuit, open circuit, or water ingress in the front/side impact sensor wiring harness causes the ECU to misdiagnose an internal hardware fault)
  • 5Software fault or calibration data corruption (interrupted flashing or electromagnetic interference causing Flash data verification failure or loss of calibration parameters)
What To Do
  • 1
    Use the VDS2000/VDS3000 diagnostic tool to read all DTCs. Confirm B16AE00 is a current fault, not a history fault. Record freeze frame data (including vehicle speed, voltage, etc. at the time of the fault). Clear the DTC and perform a road test to verify if the fault returns.
  • 2
    Check the SRS ECU power supply system: measure the voltage at the ECU connector B+ terminal (standard 12V ± 0.5V), check the dedicated SRS fuse in the dashboard fuse box (usually F1/15 10A or F2/10 15A), and check ground terminals G301/G302 for tightening torque (standard 9-11 N·m) and oxidation.
  • 3
    Check the CAN communication lines: measure the voltage to ground at diagnostic connector terminals 6 (CAN-H) and 14 (CAN-L) (CAN-H: 2.5-3.5V, CAN-L: 1.5-2.5V). Disconnect power, measure the termination resistance between the two lines (60Ω±5Ω), and check for a short to ground or short to power.
  • 4
    Check the wiring harness connector: Disconnect the negative battery terminal and wait 3 minutes. Unplug the SRS ECU connector (usually located under the center console or floor). Inspect the terminals for backing out, corrosion, or water ingress. Measure the insulation resistance of the crash sensor circuit to ground/power (must be greater than 10MΩ).
  • 5
    Software processing and calibration: Perform online ECU programming or update the software to the latest version, and refresh the calibration data. For some models, execute the 'SRS system initialization' or 'VCU and SRS matching' procedure.
  • 6
    Component replacement and verification: If the above checks pass and the software flash fails, replace the SRS ECU (verify the part number for the vehicle model; e.g., E2 uses EC-3636010). After replacement, perform anti-theft matching, sensor calibration, and a system self-test. Verify the warning light turns off and no fault codes remain.
Real-World Cases
BYD DTC AI Analysis

Poor ground connection caused an intermittent fault in the Qin Pro DM.

✓
While driving, the airbag warning light illuminated intermittently. The scan tool showed B16AE00 as an intermittent fault. Inspection found the SRS ECU ground wire G302 at the dashboard crossmember had insufficient mounting bolt torque (only 3 N·m), causing excessive contact resistance (measured 2.8 Ω, standard <0.5 Ω). Retightened the bolt to the standard torque of 10 N·m, applied conductive paste, cleared the fault code, and monitored the vehicle for two weeks without recurrence.
BYD DTC AI Analysis

E2: Abnormal sensor impedance after accident repair

✓
After front-end collision repairs, the airbag warning light stayed on. Reading codes retrieved current fault B16AE00. Inspection found the workshop had fitted an aftermarket front impact sensor; its internal resistance (2.1kΩ) fell outside the OEM specification (1.8-2.0kΩ), triggering the ECU’s diagnostic alarm. Replaced the sensor with a genuine unit (PN BYD-3636010) and performed the ‘Impact Sensor Calibration’ routine using VDS, which cleared the fault.
BYD DTC AI Analysis

E3 ECU internal corrosion after wading through water

✓
After the vehicle drove through water, the airbag warning light illuminated. Diagnosis retrieved DTC B16AE00 which could not be cleared. Disassembly and inspection revealed the SRS ECU mounted beneath the floor; the housing seal had deteriorated, allowing water ingress, and the internal PCB had green corrosion. Replaced the SRS ECU with a new unit, waterproofed the wiring harness connector (replaced the waterproof plug and applied silicone grease), and raised the ECU mounting position to prevent further water ingress. Fault completely resolved.
BYD DTC AI Analysis

Qin EV software bug caused communication timeout

✓
No accident history. The airbag warning light illuminated suddenly during normal driving, accompanied by DTCs B16AE00 and U0151 (loss of communication with SRS). Inspected the power supply, CAN bus and earth circuits – all readings normal. Diagnosed as a bug in the early software version. Performed an online upgrade using VDS3000, updating the SRS software from V1.02 to V2.15. Refreshed the calibration data and cleared the faults. No recurrence after one month of monitoring.
BYD DTC AI Analysis

Assembly defect in new E2 caused connector pin to back out.

✓
Found the airbag warning light permanently illuminated during new vehicle PDI. Retrieved current fault code B16AE00. Inspection revealed the SRS ECU wiring harness connector (32-pin) was not fully locked, with pin 15 (IGN power) backed out, causing loss of power to the ECU. Reseated the connector and confirmed the locking tab was fully engaged. Measured normal continuity across all terminals. Cleared the fault codes and the system returned to normal.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.