AU
B16C0-00

DTC B16C0-00 indicates the Airbag Electronic Control Unit (SRS ECU) detected an abnormality during its internal self-check — Atto 3

Safety System

DTC B16C0-00 indicates the Airbag Electronic Control Unit (SRS ECU) detected an abnormality during its internal self-check.

This typically indicates a hardware fault in the ECU internal processor, memory, or power management module, or a communication failure between the ECU and the vehicle CAN network.

This fault forces the airbag system into fail-safe mode.

In a collision, the system may fail to deploy the airbags and seat belt pretensioners, or activate the high-voltage interlock cut-off function, posing a severe safety risk.

This DTC is a hard fault and generally will not clear automatically.

Perform a hardware-level repair or replace the ECU.

The B16C0-00 fault code on the Atto 3 indicates an internal self-check fault in the airbag control unit. Severity is medium, but it can affect airbag, seat belt pretensioner, and high-voltage safety functions. Common causes include internal ECU circuit board damage or unstable power/ground supply. Visit an authorised dealer for diagnosis; ECU repair or replacement is usually required. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Damaged components on the SRS ECU internal circuit board (e.g., swollen electrolytic capacitor, cold solder joint on the main control chip, or chip breakdown)
  • 2Abnormal ECU power supply circuit (unstable voltage at constant power supply B+ or ignition power supply IG1, poor fuse contact, or oxidized ground point)
  • 3Vehicle CAN network communication fault (short circuit between CAN-H and CAN-L, short to ground, or open circuit prevents the ECU from communicating with the vehicle)
  • 4ECU internal memory data corruption or software version defect (program loss due to interrupted flashing or electromagnetic interference)
  • 5Vehicle water ingress or high humidity causes ECU seal failure, resulting in internal PCB corrosion or pin oxidation.
What To Do
  • 1
    Use the VDS diagnostic tool to read the complete DTC and freeze frame data. Confirm environmental parameters at the time of the fault, such as vehicle speed, supply voltage, and temperature. Attempt to clear the fault code to verify if it is an intermittent fault.
  • 2
    Disconnect the 12V battery negative terminal, wait 3 minutes, then remove and inspect the SRS ECU (usually located under the center console or beneath the center armrest). Inspect the housing seal and check for internal water marks, burn marks, or physical damage.
  • 3
    Connect the ECU wiring harness connector (do not disconnect). Measure the voltage between the power supply terminals (B+, IG1) and ground (normal: 12V ± 0.5V). Measure the ground terminal resistance (should be less than 1Ω). Check the CAN-H (2.5-3.5V) and CAN-L (1.5-2.5V) voltages, and the terminating resistance (approx. 60Ω).
  • 4
    If the wiring is normal, update the ECU software (requires the latest VDS version and official firmware). After the update, reprogram the coding and perform an airbag system function test.
  • 5
    If the software update fails, replace the SRS ECU with the same model (the part number must match exactly). Configure the new ECU online, write the VIN, and calibrate the crash sensor zero point.
  • 6
    After reassembly, connect the diagnostic tool to clear the fault code. Perform static and dynamic road tests to verify B16C0-00 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Qin EV300 SRS ECU supply voltage instability causing intermittent fault

✓
A 2017 Qin EV300 had an intermittent airbag warning light while driving. The scanner retrieved DTC B16C0-00. Inspection found a loose connection at the ECU power fuse FB11 (15A) socket, causing the ignition switch IG1 supply voltage to fluctuate severely between 11.2–13.8V. The technician sanded the fuse socket contacts; voltage stabilized at 12.4V, and the fault code did not return.
Original source ↗
BYD DTC AI Analysis

Song DM SRS ECU internal corrosion after water wading

✓
After driving through flood water, the airbag warning light stayed on with DTC B16C0-00 logged. Upon disassembly, found the ECU mounted beneath the floor. The seal had perished, allowing water ingress and causing green copper corrosion on the internal PCB. Cleaned and dried the module but the fault remained. The internal voltage regulator circuit output measured out of spec. Replaced the SRS ECU, performed crash sensor calibration, and cleared the fault.
BYD DTC AI Analysis

Tang EV: CAN Network Short Circuit Triggers SRS ECU Communication Fault

✓
After the collision repair, the dashboard displayed an airbag warning. Diagnosis found DTC B16C0-00 accompanied by multiple U-code communication faults. Measuring pins 6 (CAN-H) and 14 (CAN-L) at the diagnostic port showed resistance of only 12Ω (normal 60Ω). Step-by-step tracing identified damaged CAN wire insulation on the right A-pillar wiring harness from the previous repair, causing abnormal parallel resistance. The fault cleared after repairing the harness.
BYD DTC AI Analysis

Qin Pro EV SRS ECU software version defect

✓
Detected DTC B16C0-00 during pre-delivery inspection (PDI). Checked power supply and earth connections – both normal. ECU showed no external damage. Cleared the fault code and switched the vehicle off and on – fault immediately returned. Performed online ECU software update using VDS (upgrade from V2.1.3 to V2.2.0). After the update, completed system configuration and function testing. Fault completely resolved.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 overview →
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.