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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 — Qin Plus

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 Qin Plus indicates a medium-severity fault in the airbag control unit, either from an internal self-check failure or abnormal network communication. Common causes include a weak power or ground supply, blown airbag fuse, low battery voltage, or internal ECU damage from moisture or aging. The airbag system may be disabled, so visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1SRS ECU power supply or ground circuit fault: Causes include a blown FB-10 (10A) airbag system fuse, low battery voltage (<9V), or poor contact at ECU ground points G104/G105, resulting in unstable ECU operating voltage or ECU 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 (the Qin series ECU mounts in the lower center console, exposing it to air conditioning 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 normal ECU communication with the instrument cluster, VTOG, and other modules.
  • 4Software or calibration data corrupted: ECU internal flash memory data checksum failed. Possible causes include 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 whether B16C6-00 is a current (Active) fault. Disconnect the battery negative terminal for 5 minutes to perform an ECU hard reset, then reconnect the power and check whether 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). Standard value: 11-14V. Measure the ground resistance at B05-3 and B05-4. Standard value: <1Ω. Inspect the lower center console wiring harness for wear or water ingress.
  • 3
    Communication line inspection: Turn 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 terminals B05-5 (CAN-H) and B05-6 (CAN-L) to ground and power to check for a short to ground or short to power.
  • 4
    ECU inspection: Remove the centre console panel and extract the SRS ECU (located behind the gear selector mechanism). Check the housing for cracks, water marks, or corrosion. If the ECU shows signs of water ingress, inspect the air conditioning drain pipe for blockages to prevent repeat damage.
  • 5
    Software update and calibration: If the wiring is normal, update the SRS ECU software (SPS programming) or rewrite the configuration data. On some Qin EV models, use the VDS to execute the 'SRS system configuration' function and write the correct vehicle VIN and airbag configuration parameters.
  • 6
    Component replacement and verification: If the above steps fail, replace the SRS ECU with the same part number (such as the 5A-5820100 series). After installing the new ECU, perform 'Online Coding' and 'Seat Occupancy Recognition Calibration'. Clear the fault codes, then perform a simulated crash test (execute 'Active Test' using the diagnostic tool) to confirm normal system function.
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 Qin Plus 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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.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.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 Qin Plus →Qin Plus 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.