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B16AD-00

DTC B16AD-00 indicates an internal fault or communication error in the Supplemental Restraint System Electronic Control Unit (SRS ECU) — Qin Plus

Safety System

DTC B16AD-00 indicates an internal fault or communication error in the Supplemental Restraint System Electronic Control Unit (SRS ECU).

As the core module of the airbag system, this control unit monitors vehicle collision acceleration in real time, processes crash sensor signals, determines airbag deployment timing, and drives the ignition circuits.

This fault may force the airbag system into Fail-Safe Mode, preventing the front dual airbags, side airbags, and curtain airbags from deploying during a collision.

The condition may also cause seat belt pretensioner failure and disrupt the crash fuel cut-off function.

The root cause typically involves an ECU internal microprocessor or memory failure, an abnormal 12V power supply (overvoltage/undervoltage), or an ECU malfunction resulting from a CAN network communication disruption, rather than a single sensor fault.

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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1SRS ECU internal circuit board fault (such as filter capacitor aging, cold solder joints on the main control chip, or chip damage)
  • 2Abnormal power supply (unstable battery voltage, blown dedicated SRS fuse, poor or corroded ECU ground)
  • 3CAN bus communication fault (Powertrain CAN or Dedicated Airbag CAN short circuit, open circuit, abnormal terminating resistor, or signal interference)
  • 4Vehicle wading or high-humidity environments cause internal ECU short circuits and PCB corrosion (Qin series ECUs mount low, making them prone to water ingress).
  • 5Incorrect post-accident vehicle repair (corrupted ECU data, uncleared crash record, or hardware impact damage)
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS 2000 or VDS 2100) to read all fault codes. Confirm B16AD-00 is a Current DTC, not a history DTC, and check for accompanying communication fault codes (such as U-codes).
  • 2
    Check the SRS ECU power supply circuit: Measure the voltage at the ECU connector B+ terminal (constant power) and IGN terminal (ignition switch power). Standard value: 11-14V. If the voltage is below 10V or above 16V, inspect and repair the power supply system.
  • 3
    Check the ground circuit: Measure the resistance between the ECU ground terminal and the body ground. Resistance must be less than 1Ω. If the resistance is too high, clean the ground point and tighten the bolt.
  • 4
    Check CAN communication: Measure resistance between diagnostic port pins 6 (CAN-H) and 14 (CAN-L) (60Ω±5Ω) and voltage to ground (CAN-H: 2.5-3.5V, CAN-L: 1.5-2.5V). If abnormal, check wiring harness for short or open circuits.
  • 5
    Check the ECU connector (usually located under the center console or in front of the gear selector) for oxidation, loose connections, or signs of water ingress. If necessary, clean with electrical contact cleaner and apply conductive paste.
  • 6
    If all circuit measurements are normal, perform the SRS ECU replacement procedure: disconnect the negative battery terminal and wait 3 minutes → remove the old ECU → install the new ECU → reconnect the power supply → use the diagnostic tool to perform ECU online programming (Coding) and write the crash threshold.
  • 7
    Clear the fault code and perform a system self-check. Confirm the airbag warning lamp completes its self-check and turns off within 6 seconds after turning the ignition switch to ON.
  • 8
    Use an airbag simulator to perform a static deployment test (without actual vehicle collision) to verify the ignition circuit resistance value (2.0-3.0Ω) and system functional integrity.
Real-World Cases
BYD DTC AI Analysis

Water damaged the SRS ECU after the Qin EV300 drove through water.

✓
A 2017 Qin EV300 had the airbag warning light on the dash stay on after driving through flood water in heavy rain. VDS scan retrieved B16AD-00 (current fault) and B1600-00 (ECU power supply abnormal). Inspection found the SRS ECU mounted on the floor beneath the centre console had visible water staining and PCB corrosion inside from the water ingress. Measured ECU power supply pin voltage at 12.4V, which was normal, but CAN communication voltage was abnormal. Replaced the SRS ECU with a new unit, then dried, cleaned, and waterproofed the wiring harness connectors. Cleared the fault codes, and the system self-test passed.
BYD DTC AI Analysis

Qin 100 aftermarket audio installation caused voltage instability, triggering a fault.

✓
Owner reported that after fitting a high-power audio system to their 2017 Qin 100, the SRS warning light would occasionally illuminate while driving, then clear after turning the vehicle off and restarting. Historical DTCs showed B16AD-00. Inspection found the modification shop had taken power directly from the battery without installing a voltage stabiliser. When the high-power audio system operated, battery voltage instantly dropped below 9V, triggering SRS ECU undervoltage protection. Technicians rewired the system, installed a dedicated voltage stabiliser, and replaced the SRS ECU that had recorded voltage abnormality events (the ECU had internally flagged the fault).
BYD DTC AI Analysis

Qin EV450 ECU internal accelerometer fault after accident repair

✓
Following front-end collision repairs on a 2018 Qin EV450, the airbag warning light remained illuminated and the seatbelt pretensioners would not reset. The scan revealed DTC B16AD-00 and multiple impact sensor communication faults. Further inspection showed that although the collision force hadn't reached the airbag deployment threshold, the impact had physically damaged the MEMS accelerometer inside the ECU. Replaced the ECU, completed online programming (writing the vehicle VIN and crash parameters), then used the diagnostic tool to run 'Collision Output Clear' and 'Configuration Reset'. The system returned to normal.
BYD DTC AI Analysis

Qin 80 ECU connector oxidised after long-term parking

✓
A 2017 Qin 80 displayed an SRS fault on startup after sitting for three months. Diagnostics revealed DTC B16AD-00 accompanied by U0155 (lost communication with the instrument cluster). Inspection showed the floor-mounted ECU connector had oxidised copper pins due to damp conditions; contact resistance had increased to 5Ω (normal <0.5Ω). Cleaning the connector pins and applying electronic protectant restored communication, but the ECU still logged an internal fault and required replacement. Long-term oxidation caused an unstable power supply, which damaged the ECU's internal circuitry.
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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.