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AU
B16BC-00

DTC B16BC-00 indicates the airbag control unit (SRS ECU) internal self-check detected a severe fault, causing the system to enter fail-safe mode — Atto 3

Safety System

DTC B16BC-00 indicates the airbag control unit (SRS ECU) internal self-check detected a severe fault, causing the system to enter fail-safe mode.

This fault involves hardware failures or data checksum errors in core ECU components, including the main control processor (MCU), internal acceleration sensor (G-sensor), power management module, or memory (EEPROM/Flash).

When this fault occurs, the SRS ECU may fail to accurately assess collision severity, preventing passive safety devices such as airbags and seat belt pretensioners from deploying correctly during a crash, or creating a risk of unintended deployment.

The system illuminates the instrument cluster airbag warning light and disables the entire airbag system.

The vehicle remains drivable but loses crash protection functions, constituting a severe fault that affects driving safety.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV300: Damaged internal power supply chip in SRS ECU causing intermittent fault

✓
A 2017 BYD Qin EV300 with 80,000 km had an intermittent airbag warning light, with DTC B16BC-00. The fault mostly appeared after the vehicle warmed up. Power supply to the ECU measured normal. Removed the SRS ECU (located beneath the centre console) and found cold solder joints on the U2 voltage regulator chip (LM2937) on the internal PCB, causing the 3.3V output to fluctuate. Re-soldered the chip and reinforced the joints to clear the fault, avoiding replacement of the expensive ECU assembly.
BYD DTC AI Analysis

Qin 100 lost memory data after battery discharge

✓
The vehicle sat for an extended period, draining the battery completely (voltage below 8V). After a jump start, the instrument cluster displayed an SRS fault. Retrieved DTC B16BC-00 (current). The scan tool showed 'configuration data checksum error'. The power loss corrupted the crash algorithm parameters in the EEPROM. I used the BYD dedicated diagnostic tool to run the 'data recovery' function, downloading the OEM configuration data for this VIN from the cloud and writing it to the ECU. The fault code cleared and the system returned to normal.
BYD DTC AI Analysis

Qin EV450 ECU internal corrosion after wading

✓
The vehicle drove through water that exceeded the door sill height, after which the SRS warning light stayed on constantly. The system logged DTC B16BC-00 along with multiple crash sensor communication faults. Inspection found traces of water ingress at the SRS ECU mounting location beneath the floor. Disassembly of the ECU housing revealed electrolytic corrosion on the internal circuit board and oxidised pins on the main control chip. Cleaning the PCB and replacing the corroded surface-mount capacitors did not resolve the issue. Replaced the ECU with a new unit, dried the wiring harness connectors, and checked for blocked drain holes, completely resolving the problem.
BYD DTC AI Analysis

Qin 80 modifications cause CAN bus interference and false alarms.

✓
The owner fitted an aftermarket dashcam (powered via the OBD port). While driving, the SRS warning light illuminated randomly. The diagnostic scanner retrieved code B16BC-00 (historical). Measurements revealed abnormal pulse interference on the CAN-H line (amplitude reaching 4.5V). After removing the aftermarket OBD power adapter, the fault did not recur. The external device either occupied the SRS ECU's CAN communication bandwidth or introduced electromagnetic interference, causing the ECU to misinterpret a communication timeout as an internal fault. Advised the owner to use fuse box constant power or cigarette lighter power instead.
BYD DTC AI Analysis

Fixed the Qin EV300 software version defect by upgrading.

✓
A 2018 BYD Qin EV300 with no accidents or modifications. SRS warning light came on suddenly, code B16BC-00. Wiring inspection found no issues. Battery disconnect reset didn’t work. Checked BYD technical bulletin TSB-SRS-2019-03 — confirmed this production batch has an ECU software bug that falsely reports internal faults when starting at temperatures between -5°C and 5°C. Upgraded software from V2.1 to V2.4, cleared the code. After one week of road testing, no recurrence.
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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.