AU
B16BE-00

DTC B16BE-00 indicates the airbag control unit (SRS ECU) detected a critical internal functional fault — Atto 3

Safety System

DTC B16BE-00 indicates the airbag control unit (SRS ECU) detected a critical internal functional fault.

This condition represents a functional failure in the ECU internal microprocessor, memory, power regulation circuit, or internal self-test logic, preventing the control unit from executing its safety monitoring algorithms.

The ECU sets this DTC during the power-on self-test if it detects an internal data checksum failure, abnormal core circuit operation, or an internal communication bus fault.

This fault forces the SRS system into fail-safe mode, potentially preventing the airbags and seat belt pretensioners from deploying correctly during a collision, or in extreme cases, creating a risk of unintended deployment.

This is a critical fault affecting occupant passive safety.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1SRS ECU internal processor or memory hardware fault (such as chip damage, cold solder joints, or corrupted memory data)
  • 2Faulty ECU internal power regulation module or abnormal voltage monitoring circuit causing unstable internal operating voltage.
  • 3Vehicle electrical system abnormalities (such as jump-starting a discharged battery or a voltage surge caused by an alternator voltage regulator fault) cause internal ECU lock-up or memory data corruption.
  • 4Defective ECU software/firmware version, or calibration data anomalies over long-term use.
  • 5Internal ECU CAN transceiver fault causing vehicle network communication interruption or error frame accumulation.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor. Wear an anti-static wrist strap and avoid using radio equipment near the airbag sensor.
  • 2
    Initial inspection: Inspect the SRS ECU housing (usually located beneath the centre console or in front of the gear selector) for physical damage, signs of water ingress, or burn marks. Inspect the G36 connector for looseness and the terminals for corrosion or backed-out pins.
  • 3
    Power and ground verification: Reconnect the battery. Measure the voltage at the constant power terminal (B+) of connector G36 and confirm it is 9-16V. Measure the resistance between G36-35 (or the corresponding ground terminal) and body ground. Confirm the resistance is less than 1Ω with no poor connection.
  • 4
    Communication line inspection: Measure the CAN-H and CAN-L lines using an oscilloscope or multimeter. Verify the terminal resistance is approximately 60Ω, the static voltages are approximately 2.5V each, and the communication waveforms are normal and undistorted.
  • 5
    Software diagnosis and reset: Use the BYD VDS or a dedicated diagnostic tool to read the complete fault codes, record the freeze frame data, and attempt to clear the fault codes. Disconnect the 12V battery negative terminal for 5 minutes, then restore power. If the fault code reappears immediately, this generally confirms a hardware fault.
  • 6
    ECU swap verification (recommended): If conditions permit, swap the SRS ECU with one from a known good vehicle of the same model (verify part numbers match). If the fault follows the ECU, this 100% confirms an internal fault within the ECU itself.
  • 7
    Replace the SRS ECU: Install the new ECU, verify the mounting bracket torque meets the specification (usually 8-10Nm), connect all wiring harnesses, verify the connectors lock into place, and clean and tighten the ECU housing ground point.
  • 8
    Programming and configuration: Use the dedicated diagnostic tool to write ECU coding, configure the VIN, match vehicle model parameters, calibrate the crash sensor, and calibrate the seat occupancy sensor.
  • 9
    System verification: Switch the power mode to ON for more than 20 seconds. Observe the instrument cluster SRS warning light to confirm it completes its self-check and turns off (normally illuminates for 6 seconds before turning off). Read DTCs to confirm B16BE-00 is not present. Perform a simulated crash signal test (if equipment is available) to verify system response.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV300 SRS control unit internal processor fault

✓
Symptoms: Dashboard airbag warning light stays on. No collision history, but the airbag system fails self-test. Diagnostic process: - Read DTC B16BE-00 with VDS. - Measured G36 connector supply voltage: 12.4 V (normal). - Measured ground resistance: 0.3 Ω (normal). - Checked CAN communication lines; found no open or short circuits. - Cleared DTC and power-cycled the system; DTC returned. Root cause: Internal processor fault in SRS ECU. Solution: Replaced airbag control unit (SRS ECU). Performed coding and sensor calibration using a dedicated diagnostic tool. After replacement, warning light went out and system self-test passed.
Original source ↗
BYD DTC AI Analysis

Voltage fluctuation caused ECU lock-up on BYD Tang DM

✓
Symptom: The airbag warning lamp illuminated suddenly during normal driving. Scan tool showed B16BE-00 and B16BF-00 (both SRS ECU faults), along with companion code B1693-00 (poor earth connection). Diagnosis: Checked the ECU housing earth point — no looseness. Measured wiring harness terminal-to-ground resistance; readings normal. Disconnected battery negative for 5 minutes, reconnected; fault codes remained. Swapped the SRS ECU with one from an identical normal vehicle; the fault transferred, confirming an ECU hardware fault. Suspect voltage surge during jump-starting after the battery went flat locked up the ECU internally. Fix: Replaced the SRS ECU assembly. On some vehicle batches, reflashing the SRS ECU software resolves the issue. After replacement, perform coding configuration and a comprehensive system check.
Original source ↗
BYD DTC AI Analysis

Prolonged high-humidity conditions caused internal ECU corrosion in BYD Qin Pro

✓
Symptoms: After parking overnight, the SRS warning light stayed on at startup. DTC B16BE-00 stored. The vehicle had previously been driven through water. Diagnosis: Inspected the SRS ECU mounting location (lower centre console) and found slight moisture traces. Removed the ECU and found slight oxidation at the circuit board edge. Measured the internal voltage regulator circuit output: abnormal. Power supply and ground circuits tested normal. Determined that damp environment caused corrosion on the ECU internal circuit board, leading to functional failure. Resolution: Replaced the SRS ECU. Dried the mounting location and reinforced waterproofing. Reprogrammed the system and eliminated the fault. Recommended checking the vehicle floor seal integrity.
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.