AU
B16BE-00

DTC B16BE-00 indicates the airbag control unit (SRS ECU) detected a critical internal functional fault — Seal 6 EV

Safety System

DTC B16BE-00 indicates the airbag control unit (SRS ECU) detected a critical internal functional fault.

This condition represents a functional failure in the ECU internal microprocessor, memory, power regulation circuit, or internal self-test logic, preventing the control unit from executing its safety monitoring algorithms.

The ECU sets this DTC during the power-on self-test if it detects an internal data checksum failure, abnormal core circuit operation, or an internal communication bus fault.

This fault forces the SRS system into fail-safe mode, potentially preventing the airbags and seat belt pretensioners from deploying correctly during a collision, or in extreme cases, creating a risk of unintended deployment.

This is a critical fault affecting occupant passive safety.

The B16BE-00 fault code on the Seal 6 EV indicates a critical internal fault in the airbag control unit (SRS ECU). Severity is medium because it can affect airbag or seat belt pretensioner operation. Common causes include ECU processor or memory failure, or an internal power regulation fault. The recommended fix is to visit an authorised dealer for diagnosis and ECU repair or replacement. Typical repair cost data is available from recorded cases.
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Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1SRS ECU internal processor or memory hardware fault (such as chip damage, cold solder joints, or corrupted memory data)
  • 2Faulty ECU internal power regulator module or abnormal voltage monitoring circuit causing unstable internal operating voltage.
  • 3Vehicle electrical system abnormalities (such as jump-starting a discharged battery or voltage surges caused by a faulty alternator voltage regulator) causing internal ECU lock-up or memory data corruption.
  • 4Defective ECU software/firmware version, or abnormal calibration data from long-term use.
  • 5Internal ECU CAN transceiver fault causing vehicle network communication interruption or error frame accumulation.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal. Wait at least 90 seconds to allow the SRS capacitor to discharge completely. Wear an anti-static wrist strap. Do not use radio equipment near the airbag sensor.
  • 2
    Preliminary check: Inspect the SRS ECU housing (usually located under the center console or in front of the gear selector) for physical damage, water ingress, or burn marks. Check connector G36 for looseness and the terminals for corrosion or backed-out pins.
  • 3
    Power and ground verification: Reconnect the battery. Measure the voltage at the constant power terminal (B+) of connector G36 and verify it is 9-16V. Measure the resistance between G36-35 (or the corresponding ground terminal) and body ground and verify it is less than 1 Ω with no poor connection.
  • 4
    Communication line inspection: Use an oscilloscope or multimeter to measure the CAN-H and CAN-L lines. Verify the terminal resistance is approximately 60Ω, the static voltages are approximately 2.5V each, and the communication waveform is normal without distortion.
  • 5
    Software diagnosis and reset: Use BYD VDS or a dedicated diagnostic tool to read all fault codes, record freeze frame data, and attempt to clear the fault codes. Disconnect the 12V battery negative terminal for 5 minutes, then restore power. If the fault code reappears immediately, this generally confirms a hardware fault.
  • 6
    ECU swap verification (recommended): If conditions permit, swap the SRS ECU with one from a known good vehicle of the same model (part numbers must match). If the fault transfers with the ECU, this confirms an internal ECU fault.
  • 7
    Replace the SRS ECU: Install the new ECU, tighten the mounting bracket to the specified torque (usually 8-10 Nm), connect all wiring harnesses and confirm they lock into place, and verify the ECU housing ground point is clean and securely tightened.
  • 8
    Programming and configuration: Use the dedicated diagnostic tool to write ECU coding, configure the VIN, match vehicle model parameters, calibrate the crash sensor, and calibrate the seat occupancy sensor.
  • 9
    System verification: Switch the power mode to ON for more than 20 seconds. Verify the instrument cluster SRS warning light turns off after completing its self-check (normally illuminates for 6 seconds, then turns off). Read DTCs to confirm B16BE-00 is not present. Perform a simulated crash signal test (if equipment is available) to verify system response.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV300 SRS control unit internal processor fault

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Symptoms: Dashboard airbag warning light stays on. No collision history, but the airbag system fails self-test. Diagnostic process: - Read DTC B16BE-00 with VDS. - Measured G36 connector supply voltage: 12.4 V (normal). - Measured ground resistance: 0.3 Ω (normal). - Checked CAN communication lines; found no open or short circuits. - Cleared DTC and power-cycled the system; DTC returned. Root cause: Internal processor fault in SRS ECU. Solution: Replaced airbag control unit (SRS ECU). Performed coding and sensor calibration using a dedicated diagnostic tool. After replacement, warning light went out and system self-test passed.
Original source ↗
BYD DTC AI Analysis

Voltage fluctuation caused ECU lock-up on BYD Tang DM

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Symptom: The airbag warning lamp illuminated suddenly during normal driving. Scan tool showed B16BE-00 and B16BF-00 (both SRS ECU faults), along with companion code B1693-00 (poor earth connection). Diagnosis: Checked the ECU housing earth point — no looseness. Measured wiring harness terminal-to-ground resistance; readings normal. Disconnected battery negative for 5 minutes, reconnected; fault codes remained. Swapped the SRS ECU with one from an identical normal vehicle; the fault transferred, confirming an ECU hardware fault. Suspect voltage surge during jump-starting after the battery went flat locked up the ECU internally. Fix: Replaced the SRS ECU assembly. On some vehicle batches, reflashing the SRS ECU software resolves the issue. After replacement, perform coding configuration and a comprehensive system check.
Original source ↗
BYD DTC AI Analysis

Prolonged high-humidity conditions caused internal ECU corrosion in BYD Qin Pro

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Symptoms: After parking overnight, the SRS warning light stayed on at startup. DTC B16BE-00 stored. The vehicle had previously been driven through water. Diagnosis: Inspected the SRS ECU mounting location (lower centre console) and found slight moisture traces. Removed the ECU and found slight oxidation at the circuit board edge. Measured the internal voltage regulator circuit output: abnormal. Power supply and ground circuits tested normal. Determined that damp environment caused corrosion on the ECU internal circuit board, leading to functional failure. Resolution: Replaced the SRS ECU. Dried the mounting location and reinforced waterproofing. Reprogrammed the system and eliminated the fault. Recommended checking the vehicle floor seal integrity.
Other Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.