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B16F912

This is an SRS (Supplemental Restraint System / airbag system) DTC — Qin Plus

Safety System

This is an SRS (Supplemental Restraint System / airbag system) DTC.

It indicates a short to the vehicle power supply (12V/B+) in a safety-related sensor circuit—typically the second signal/communication line of the seat occupancy sensor, seat belt pretensioner sensor, or side impact sensor.

In the BYD DTC structure, "B16F9" designates the second-row Occupant Classification System (OCS) or the seat belt anchorage sensor, and the "12" suffix indicates a short to power.

This fault causes the Airbag Control Unit (ACU) to detect an abnormally high signal voltage.

The ACU then triggers the safety protection mechanism and places the affected airbag circuit into fail-safe mode.

In extreme cases, this prevents correct airbag deployment during a collision or generates false warnings.

Consequently, the system illuminates the airbag warning lamp and prevents vehicle operation.

The B16F912 fault code on the Qin Plus indicates a high-severity airbag/SRS fault caused by a short to 12V power in a second-row occupant, seat belt anchorage, or related sensor circuit. Common causes include damaged seat or sill-area wiring, or an internal sensor electronics failure. The airbag warning light may come on and protection may be disabled. Visit an authorised BYD dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Damaged wiring harness insulation causes a short circuit by contacting body power lines (such as the seat heating power wire or constant power circuit). This commonly occurs in areas with frequent seat slide rail adjustment or due to harness wear inside the door sill trim panel.
  • 2Breakdown of internal sensor electronic components or a capacitor short circuit causes the signal line to connect directly to the sensor internal power supply terminal.
  • 3Connector terminal corrosion due to water ingress or pin misalignment (such as a bent pin contacting an adjacent power terminal), especially in vehicles with damp under-seat environments or a history of wading or liquid spills.
  • 4Improper aftermarket modifications (such as installing seat heaters, massage cushions, or tapping power for a dashcam) pierced or damaged the SRS sensor wiring harness insulation.
  • 5Internal signal processing circuit fault in the Airbag Control Unit (ACU) causes the reference voltage output to the sensor to rise abnormally and feed back as a short to power.
What To Do
  • 1
    Use BYD dedicated diagnostic tool VDS2000/VDS3000 to read the complete fault codes and freeze frame data. Record the vehicle status at the time of the fault. Perform a system self-check to confirm B16F912 is currently present and is a hard fault.
  • 2
    Refer to the vehicle repair manual wiring diagram to locate the specific sensor (typically the second-row seat occupancy sensor or seat belt buckle sensor). Visually inspect the connector for looseness, water ingress, or obvious burn marks.
  • 3
    Disconnect the sensor connector. Use a multimeter to measure the voltage between the 'second wire' on the wiring harness side (usually the signal or LIN wire) and body ground. The voltage should be close to 0V or the 5V reference voltage. A 12V battery voltage reading confirms a short to power.
  • 4
    Use a sectional troubleshooting method: follow the harness routing to check the harness securing at the seat slide rail, under the carpet, and inside the B-pillar trim. Focus on locating chafing points between the harness and sharp metal edges, the seat heater harness, or the power harness. Repair the insulation at any damaged areas, reroute the harness, and install corrugated conduit for protection.
  • 5
    If the wiring harness is intact, measure the resistance between the sensor terminals. If the resistance between the signal wire and the power supply terminal is 0 or very low, the sensor has an internal short circuit. Replace the corresponding sensor (such as the seat occupancy pressure sensor or seat belt buckle switch).
  • 6
    After inspection and repair, reconnect all connectors, use the diagnostic tool to clear the fault codes, and perform SRS system configuration calibration (such as the seat OCS calibration procedure). Finally, perform static and road tests to confirm the fault light turns off and the system generates no new fault codes.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM seat occupancy sensor wiring harness chafed and shorted to the heating wire

✓
The instrument cluster displayed a permanent airbag warning light. VDS read fault code B16F912. Inspection found the wiring harness retaining clip under the second-row seat had detached. The Occupant Classification Sensor (OCS) signal wire insulation had chafed through and contacted the parallel seat heater power wire (12V constant), causing a short to power. Repaired the damaged harness section, rerouted the wiring to avoid the seat rail travel area, and replaced the cable ties. Fault cleared.
BYD DTC AI Analysis

BYD Qin Pro (petrol): Water ingress short-circuited seatbelt pretensioner connector.

✓
The airbag warning light illuminated after the vehicle was driven through water. The scan tool displayed DTC B16F912. Inspection revealed water inside the driver's side seatbelt pretensioner connector (located beneath the B-pillar). Electrochemical corrosion on the terminals caused a short circuit between the signal and power terminals. The technician cleaned the connector with electronic contact cleaner, dried it thoroughly, applied conductive paste, and reinstalled it. After clearing the fault codes, the system returned to normal. Check the door seals to prevent further water ingress.
BYD DTC AI Analysis

Aftermarket seat heating modification damaged the sensor wiring, causing a short circuit.

✓
The owner fitted an aftermarket passenger seat heating pad, causing the airbag warning light to illuminate. Diagnosis revealed DTC B16F912. Inspection found metal staples used to secure the heating pad harness during the modification had pierced the second signal wire of the factory seat occupancy sensor, shorting it to the heating pad power wire. Resoldered and insulated the damaged sensor wiring with heat-shrink tubing, rerouted the harness properly, removed the metal staples and secured the loom with dedicated harness tape. Fault resolved.
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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.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 Qin Plus →Qin Plus 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.