AU
B16C6-00

DTC B16C6-00 indicates the Airbag Control Unit (SRS ECU) detected an internal self-check fault or abnormal communication with the vehicle network — Seal 6 EV

Safety System

DTC B16C6-00 indicates the Airbag Control Unit (SRS ECU) detected an internal self-check fault or abnormal communication with the vehicle network.

The SRS ECU is the core controller of the passive safety system, monitoring crash sensors, seat occupancy detection, seat belt pretensioners, and individual airbag modules.

When this DTC triggers, the ECU may enter fail-safe mode, degrading or completely disabling the entire airbag system.

As a result, the front dual airbags, side airbags, and pretensioning seat belts may fail to deploy during a collision.

This is a hard fault and will not clear automatically after a vehicle restart.

Troubleshooting requires professional diagnostic equipment.

The B16C6-00 fault code on the Seal 6 EV indicates the SRS airbag control unit has found an internal self-check fault or abnormal network communication. Severity is medium because airbags and seat belt pretensioners may be disabled or work improperly in a crash. Common causes include low or unstable power/ground supply, a blown airbag fuse, or internal SRS ECU damage. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
4
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Abnormal SRS ECU power supply or ground circuit: Includes a blown FB-10 (10A) airbag system fuse, low battery voltage (<9V), or poor contact at ECU ground points G104/G105, causing unstable ECU operating voltage or reset.
  • 2SRS ECU internal hardware fault: Damaged ECU internal microprocessor, memory (EEPROM), or crash sensor interface circuit. Common causes include vehicle water ingress, moisture at the ECU mounting location, or component aging (on Qin series vehicles, the ECU sits in the lower center console, exposing it to A/C condensation).
  • 3CAN communication bus fault: Short circuit, open circuit, or abnormal terminal resistance in the Power CAN (CAN-H/CAN-L) lines between the SRS ECU and the gateway (GW), preventing the ECU from communicating with the instrument cluster, VTOG, and other modules.
  • 4Software or calibration data corrupted: ECU internal flash memory data checksum failed, possibly due to interrupted programming, improper battery disconnection, or electromagnetic interference.
  • 5Crash data locked: After a minor collision, the SRS ECU records the collision event and locks (Crash Data Locked). Replace or unlock the ECU.
What To Do
  • 1
    Preparation and Diagnosis: Use the ED-400 or VDS2000 diagnostic tool to access the SRS system. Read the complete fault code list, record the freeze frame data, and confirm if B16C6-00 is a current fault (Active). Disconnect the battery negative terminal for 5 minutes to perform an ECU hard reset. Reconnect power and check if the fault code reappears.
  • 2
    Power supply and ground check: Check if the FB-10 fuse (10A) in the engine compartment fuse box is blown. Measure the voltage to ground at SRS ECU connectors B05-1 (constant power +B) and B05-2 (IGN power); the standard value is 11-14V. Measure the ground resistance at B05-3 and B05-4; it should be <1Ω. Inspect the wiring harness under the center console for wear or water ingress.
  • 3
    Communication line inspection: Turn the ignition switch OFF. Measure the resistance between diagnostic connector pins 6 (CAN-H) and 14 (CAN-L). Standard value: 60 ± 6 Ω. Measure the insulation of SRS ECU connector pins B05-5 (CAN-H) and B05-6 (CAN-L) to ground and power. Check for a short to ground or short to power.
  • 4
    ECU module inspection: Remove the centre console panel and extract the SRS ECU (located behind the gear selector mechanism). Inspect the housing for cracks, water stains, or corrosion. If water ingress is present, also check the air conditioning drain pipe for blockages to prevent repeated damage.
  • 5
    Software update and calibration: If the wiring is normal, update the SRS ECU software (SPS programming) or rewrite the configuration data. Some Qin EV models require executing the 'SRS System Configuration' function via VDS to write the correct vehicle VIN and airbag configuration parameters.
  • 6
    Component replacement and verification: If the previous steps fail, replace the SRS ECU with the same part number (e.g., 5A-5820100 series). After installing the new ECU, perform "online coding" and "seat occupancy recognition calibration". Clear the fault code, then perform a simulated crash test (use the diagnostic tool to execute an "activation test") to confirm normal system operation.
Real-World Cases
BYD DTC AI Analysis

Qin EV300 instrument panel SRS warning light stays on, with DTC B16C6-00

✓
A 2017 Qin EV300 with 80,000 km on the clock had the airbag warning light on the instrument panel stay on continuously. Used VDS2000 to retrieve codes B16C6-00 (SRS ECU fault) and U0151 (lost communication with SRS ECU). Found green corrosion on SRS ECU connector B05, located beneath the centre console. Disassembly revealed the air conditioning evaporator drain hose had detached, allowing condensate to seep into the ECU mounting cavity. Replaced the SRS ECU (part number 5A-5820100), corrected the drain hose routing, and fitted a waterproof gasket at the ECU bracket. After fixing the fault, performed seat occupancy sensor calibration and the system self-check passed.
BYD DTC AI Analysis

Qin 80 SRS system won't come online after accident repair

✓
A 2017 BYD Qin 80 sustained a minor front impact. After a repair shop replaced the front bumper and radar sensors, DTC B16C6-00 appeared and could not be cleared. Diagnosis found the SRS ECU had stored a crash event (Crash Data) and entered a locked state. Since BYD SRS ECUs are single-use (unless officially unlocked), attempts to clear the code failed. Final solution: Replaced the SRS ECU with a new one, used the ED-400 to perform the 'New Module Assembly' procedure, and programmed the VIN and configuration data (front dual airbags plus side airbags). The airbag warning light went out after the self-check.
BYD DTC AI Analysis

Qin EV450 intermittent SRS warning light accompanied by multi-system communication fault.

✓
A 2018 Qin EV450 intermittently displayed an SRS warning light accompanied by heavy steering (EPS fault). The diagnostic tool retrieved DTC B16C6-00 and multiple U-series communication fault codes. CAN-H resistance to ground at the diagnostic connector measured 2.3 Ω (abnormal). Tracing section by section pinpointed the fault to the CAN bus junction under the left A-pillar, where the SRS ECU CAN wire had chafed against a metal bracket, wearing through the insulation and shorting to ground. After repairing the harness and rerouting the wiring, all communication faults and DTC B16C6-00 disappeared, and the SRS system returned to normal operation.
BYD DTC AI Analysis

Qin 100: SRS system reports ECU fault after battery replacement

✓
A 2017 Qin 100 displayed 'SRS System Fault' on the dash after a general repair shop replaced the battery. Retrieved DTC B16C6-00. The technician had not disconnected the negative battery terminal during the replacement, causing power fluctuations during removal and installation that triggered an SRS ECU internal data validation error. Used VDS to perform 'SRS ECU Programming' and reflashed the SRS ECU with the latest 5A-5820100 series software (version upgraded from V1.2 to V1.4). After programming, executed 'System Configuration' and 'Clear Collision Records'. The fault code cleared and the airbag system passed self-diagnosis.
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.