AU
B16C0-00

DTC B16C0-00 indicates the Airbag Electronic Control Unit (SRS ECU) detected an abnormality during its internal self-check — Seal 6 EV

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.

4
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Damaged components on the SRS ECU internal circuit board (e.g., bulging electrolytic capacitor, cold solder joint on the main control chip, or chip breakdown)
  • 2ECU power supply circuit fault (unstable voltage at constant power B+ or ignition power 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 in the wiring prevents the ECU from communicating with the vehicle)
  • 4ECU internal memory data corruption or software version defect (interrupted flashing process or electromagnetic interference causing program loss)
  • 5Vehicle wading 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 DTCs and freeze frame data. Check environmental parameters such as vehicle speed, power supply voltage, and temperature at the time of the fault. Attempt to clear the fault code to verify if it is an intermittent fault.
  • 2
    Disconnect the battery negative terminal, wait 3 minutes, then remove and inspect the SRS ECU (usually located under the center console or at the base of the center armrest). Check the housing seal and inspect the interior for water stains, burn marks, or physical damage.
  • 3
    Leave the ECU wiring harness connector connected. 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 voltage (2.5-3.5V), CAN-L voltage (1.5-2.5V), and terminating resistance (approximately 60Ω).
  • 4
    If the wiring is normal, flash the ECU software (using the latest VDS version and official firmware). After flashing, re-match the coding and perform an airbag system function test.
  • 5
    If the software flash fails, replace the SRS ECU with the same model (the part number must match exactly). Perform online configuration, VIN writing, and crash sensor zero-point calibration on the new ECU.
  • 6
    After reassembly, connect the diagnostic tool and clear the fault code. Perform static and dynamic road tests to verify B16C0-00 does not reappear and the airbag warning light turns off normally.
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 Seal 6 EV Fault Codes
B1108For 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.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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.