AU
B16AD-00

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

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.

The B16AD-00 fault code on the Seal U indicates an internal fault or communication error in the SRS ECU (airbag control unit), which may prevent airbags and seat belt pretensioners from deploying during a crash. Severity is medium. Common causes include internal circuit board faults or abnormal power supply. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available based on 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1SRS ECU internal circuit board fault (such as filter capacitor aging, main control chip cold solder joints, or 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 causes an internal ECU short circuit and PCB corrosion (the Qin series ECU mounts low, making it prone to water ingress).
  • 5Improper repair after vehicle accident (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 the complete fault codes. Confirm B16AD-00 is a current fault (Current DTC), not a history fault, and check for accompanying communication fault codes (such as codes starting with U).
  • 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). The standard value is 11-14V. If the voltage is below 10V or above 16V, repair the power supply system.
  • 3
    Check the ground circuit: Measure the resistance between the ECU ground pin and the body ground. The 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 connector pin 6 (CAN-H) and pin 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, looseness, or signs of water ingress. If necessary, clean with electrical contact cleaner and apply conductive grease.
  • 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 ON.
  • 8
    Use an airbag simulator to perform a static deployment test (not an actual vehicle collision) and 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 Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U overview →
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.