AU
B16A7-00

The definition of DTC B16A7-00 varies across BYD vehicle platforms — Seal U

Safety System

The definition of DTC B16A7-00 varies across BYD vehicle platforms.

In early models such as the Qin 100, Qin 80, and Qin EV450, this code indicates an internal fault in the SRS_ECU (airbag control unit).

It signifies an abnormality in the main control chip, internal memory, or ignition circuit driver, preventing the airbag system from executing collision detection and airbag deployment logic.

DM-i and e-Platform 3.0 models, such as the Qin PLUS, Song Pro, and Tang DM, often reuse this DTC as a hardware fault code for the seat occupancy recognition sensor (SBR) or the ultrasonic radar/blind spot monitoring radar.

This indicates the ECU received an invalid or out-of-range sensor signal.

Regardless of the definition, this fault causes the airbag system to enter degraded mode and illuminates the instrument cluster SRS warning lamp.

It may also cause seat belt pretensioner failure, airbag suppression, or a risk of unintended deployment.

Repair immediately.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Seat occupancy detection sensor (pressure film) fatigue fracture or open circuit. Prolonged improper sitting posture or frequent seat adjustment commonly breaks the film wiring (Qin PLUS/Han models).
  • 2Water ingress and oxidation at the radar sensor wiring harness connector, especially after wading or car washing; poor rear bumper wiring harness sealing causes terminal corrosion and open circuits (Song Pro/Tang DM models).
  • 3Damaged internal transducer or shorted coil in the ultrasonic/millimetre-wave radar sensor, typically resulting from minor impacts, paint coverage, or internal ageing (Yuan Pro/Song Pro models).
  • 4OTA update or software flashing causes radar configuration file loss, and module communication parameters do not match actual vehicle configuration (Han EV/Seal models).
  • 5Damaged SRS_ECU internal power management chip or sensor interface circuit, typically resulting from jump-starting a depleted battery, voltage surges, or prolonged exposure to high temperatures (Qin 100/Qin EV models).
What To Do
  • 1
    Use BYD dedicated diagnostic tool VDS2000 or Launch X431 to read the complete fault code stream. Confirm the B16A7-00 subtype description (e.g., 'left rear radar', 'driver seat sensor', or 'SRS internal') and record the freeze frame data.
  • 2
    Check the waterproof sealing of the SRS system wiring harness connectors (especially under the seats and inside the bumper). Measure the sensor supply voltage (12V ± 0.5V or 5V ± 0.25V, depending on the specific sensor) and CAN line voltage (CAN-H 2.6V / CAN-L 2.4V).
  • 3
    For seat occupancy detection faults: Remove and inspect the pressure film sensor inside the seat foam. Measure the resistance (normal: 2.5-3.5 kΩ). If the circuit is open, replace the sensor assembly (part number SA-3654200) and calibrate the seat sensor using VDS.
  • 4
    For radar system faults: Inspect the radar sensor surface for dirt, dents, or paint. Remove and inspect the sensor, then measure the internal resistance (normal: 1.2-1.8 kΩ). If shorted or open, replace the corresponding sensor. Use the dedicated calibration tool to adjust the installation angle to within ±3° of horizontal.
  • 5
    For an internal SRS_ECU fault: Check the ECU power supply and ground circuits. If the external circuits are normal, replace the SRS_ECU (use VDS to perform ECU coding, write the VIN, and clear the collision history), and write the system configuration (set the correct number of radars or seat type).
  • 6
    Clear all fault codes. Perform an SRS system self-diagnosis (cycle the ignition switch 3 times) and verify the fault code does not return. Perform a vehicle collision simulation test (use the diagnostic tool to trigger the sensor signal) to verify system response.
Real-World Cases
BYD DTC AI Analysis

Water ingress caused oxidation in the left rear radar wiring harness of the Song Pro, resulting in DTC B16A7-00

✓
Symptoms: Vehicle displays 'Please check radar system' on startup. Reversing radar inoperative, 360° camera black screen. Diagnostic tool reads DTC B16A7-00 (Left rear radar sensor fault). Diagnosis: Measured 0V supply voltage at left rear radar sensor. Inspected wiring harness connector inside bumper; found water ingress and oxidation, terminals corroded causing open circuit. Resolution: Cleaned oxidised terminals, sprayed WD-40 for rust prevention, rewrapped wiring harness with waterproof tape, cleared fault codes. System returned to normal.
Original source ↗
BYD DTC AI Analysis

Qin PLUS DM-i driver's seat occupancy sensor broken

✓
Symptoms: The instrument cluster displays 'Airbag System Fault' and the driver's seat occupancy indicator stays on continuously regardless of whether the seat is occupied. Diagnosis: VDS read DTC B16A7-00, pointing to the driver's seat occupancy sensor. Measuring the sensor resistance showed an open circuit (normal: 2.5-3.5kΩ). Inspection found a fractured pressure film inside the seat foam. Resolution: Replaced the driver's seat occupancy recognition sensor assembly (SA-3654200), performed sensor calibration using VDS, and cleared the fault codes. The system then operated normally.
Original source ↗
BYD DTC AI Analysis

Tang DM left rear blind spot monitoring radar damaged and bracket deformed

✓
Symptoms: Blind spot monitoring warning light flashed erratically while driving, and lane change assist failed. Stored DTC B16A7-00 (left rear blind spot radar signal abnormal). Diagnosis: Live data showed left rear radar signal strength at 0. Inspection found a minor impact dent on the surface of the left rear radar sensor on the rear bumper. Disassembly found internal transducer damage and bracket mounting angle offset by 15°. Solution: Replaced left rear blind spot monitoring radar sensor (3655100-XX). Readjusted mounting angle using dedicated calibration tool. Performed BSD system self-learning.
Original source ↗
BYD DTC AI Analysis

Han EV radar communication fault after OTA update

✓
After OTA update, display showed 'Parking Assist System Fault'. Front and rear radars inoperative. Read DTCs B16A7-00 and U0155-00 (radar communication fault). Diagnosis: Checked radar module power and CAN lines – both normal. Attempted programming; system returned 'Sensor Configuration Error'. Compared with a normal vehicle; found abnormal radar quantity configuration (configuration file missing). Solution: Rewrote radar configuration file using VDS2000. Ran 'Radar System Configuration', set correct radar count (front 4, rear 4). Activated each radar sensor individually; fault cleared.
Original source ↗
BYD DTC AI Analysis

Yuan Pro right rear center parking sensor internal short circuit

✓
Symptoms: When reverse gear is engaged, the parking sensor emits a continuous alarm despite no obstacles behind the vehicle. The display shows a fixed distance of 0.3 m. DTC B16A7-00 (right rear centre parking sensor fault). Diagnosis: Inspected the sensor surface and found paint residue. Cleaned the sensor, but the fault persisted. Removed the sensor and tested it with a direct power supply, finding a weak transmission signal. Measured the internal coil and identified a short circuit. Solution: Replaced the right rear centre parking sensor (3655400-XX). Performed radar position learning using a diagnostic tool. Tested all sensors and confirmed detection distances returned to normal.
Original source ↗
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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.