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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 — Seal U

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.

4
Cases Logged
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.

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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 U 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.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.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.
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.