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B16C0-00

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

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
Real-World Cases
BYD DTC AI Analysis

Qin EV300 SRS ECU supply voltage instability causing intermittent fault

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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

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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

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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

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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 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.