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B16C1-00

DTC B16C1-00 indicates an internal fault or functional failure of the airbag system electronic control unit (SRS_ECU) — Qin Plus

Safety System

DTC B16C1-00 indicates an internal fault or functional failure of the airbag system electronic control unit (SRS_ECU).

This fault represents a core self-check abnormality of the airbag control module.

It typically indicates a hardware-level fault in the ECU internal processor, memory, power management circuit, or safety monitoring circuit.

This fault causes the airbag system to enter a degraded mode or complete failure state.

During a collision, the system may fail to deploy the airbags, making this a critical fault affecting vehicle passive safety.

Upon fault detection, the SRS system typically illuminates the instrument cluster airbag warning light (solid) and logs a non-clearable hard fault code.

Some models may also trigger the seat belt pretensioner disable logic.

4
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Qin EV300 SRS warning light came on suddenly while driving

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A 2017 Qin EV300 with 82,000 km came in because the airbag warning light suddenly came on and stayed on while driving. We scanned with a VDS2000 and retrieved DTC B16C1-00 (SRS ECU fault). The vehicle had no collision history. The ECU supply voltage was normal (12.4 V), and the CAN bus waveform was also normal, but the DTC returned immediately after clearing. Disassembling the ECU revealed obvious burn marks on the internal PCB, indicating the power management chip had failed. We replaced the SRS ECU with a new unit (Part No.: BYD-3638100-X00), performed online programming and sensor calibration, and the fault was resolved.
BYD DTC AI Analysis

B16C1-00 occurs intermittently after accident repair

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2018 BYD Qin EV450. After front collision repairs, the SRS warning light illuminated intermittently. The scan tool displayed current DTC B16C1-00 with history DTC U0140 (lost communication with SRS ECU). Inspection revealed the accident had slightly deformed the ECU mounting bracket, causing the ECU housing to contact the metal bracket and create stress, along with a poor connection on pin 12 (constant power) of the ECU connector. After repairing the harness connector and replacing the deformed bracket, DTC B16C1-00 still appeared occasionally. The accident impact and voltage fluctuations had damaged the ECU internal circuitry. Replacing the ECU resolved the fault completely.
BYD DTC AI Analysis

SRS system failure on water-wading vehicle

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2017 BYD Qin 100. After wading through water up to seat height in heavy rain, the SRS warning light stayed on after towing. Read fault codes: B16C1-00 and multiple airbag igniter short circuit faults. Inspection found the SRS ECU seal beneath the centre tunnel had failed, with severe internal circuit board corrosion and several broken, oxidised copper traces. Cleaned the wiring harness connectors and confirmed normal insulation readings. Replaced the ECU and sealing gasket, and dried the ECU mounting compartment. Performed full system configuration after replacement. Cleared the fault codes and confirmed all airbag circuit resistances returned to normal (2.0–2.8 Ω).
BYD DTC AI Analysis

Replaced the ECU after software flash failure.

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A 2017 BYD Qin 80 set DTC B16C1-00 after an SRS software update at a dealership. The vehicle had no collision history. Diagnosis showed the ECU lost power while reflashing, corrupting the internal data. Reflash attempts triggered a 'security authentication failed' warning. Power, ground, and communication circuit checks were all normal. The ECU internal flash memory was faulty. Replaced the ECU with an identical unit. Using the dedicated diagnostic tool, ran the 'airbag control unit replacement' procedure: wrote the VIN and configuration parameters, then performed 'lateral/longitudinal acceleration sensor calibration'. Fault cleared.
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.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.