AU
B16DF-00

This fault code indicates the SRS (airbag) control unit detects a communication interruption or no connection with the Left Rear Impact Sensor — Qin Plus

Safety System

This fault code indicates the SRS (airbag) control unit detects a communication interruption or no connection with the Left Rear Impact Sensor.

This sensor typically mounts in the vehicle’s left rear side panel, C-pillar, or rear door area to monitor side-impact acceleration signals.

The SRS ECU triggers this fault if it fails to receive valid data from the sensor within a predetermined time, or if it detects circuit resistance outside the normal range (open or short circuit).

This fault disables the vehicle’s side-impact detection function.

The system may fail to accurately determine collision severity, suppressing normal deployment of the left rear side airbag/side curtain airbag.

In some cases, this creates a risk of unintended airbag deployment in fail-safe mode.

The B16DF-00 fault code on the Qin Plus indicates a medium-severity communication fault between the SRS airbag control unit and the left rear impact sensor. This can disable left rear side-impact detection and may affect side airbag or curtain airbag operation. Common causes include damaged wiring near the rear door/sill area or a loose, corroded sensor connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Broken or crushed left rear impact sensor wiring harness, especially at harness bends routed through the door hinge or inside the sill trim panel where long-term vibration fractures the copper wires.
  • 2Loose sensor connector, backed-out terminal, or corrosion from water ingress. Poor sealing after driving through water or vehicle washing frequently causes terminal oxidation.
  • 3Internal crash sensor accelerometer damage or a circuit fault causes no signal output.
  • 4SRS control unit internal detection circuit fault preventing correct identification of sensor signals (less common)
  • 5Wiring harness accidentally cut or connector not fully seated during accident repairs or vehicle modifications (such as window tinting or audio system installation).
What To Do
  • 1
    Connect the BYD dedicated diagnostic tool (VDS or ED400). Read the complete fault codes and freeze frame data. Confirm the vehicle speed, timestamp, and other data recorded at the time of the fault.
  • 2
    Switch off the ignition, disconnect the negative battery terminal, and wait at least 90 seconds to fully discharge the SRS system high-voltage capacitor.
  • 3
    Remove the left rear interior trim panel (lower C-pillar trim panel or left rear door sill trim panel) and locate the left rear impact sensor (usually marked 'LEFT REAR' or 'LR').
  • 4
    Check the sensor connector for looseness or backed-out pins. Inspect the terminals for green corrosion or water marks. If necessary, clean the terminals with electrical contact cleaner and apply conductive grease.
  • 5
    Use a multimeter to measure sensor wiring harness continuity: check the circuit resistance between the sensor connector and the SRS ECU (less than 1 Ω), and check the insulation resistance to ground (greater than 1 MΩ).
  • 6
    Measure the sensor internal resistance (refer to the workshop manual standard value, usually 2-5 kΩ). If the resistance is infinite or zero, replace the sensor.
  • 7
    If the wiring harness is damaged, repair or replace it. Protect the harness with high-temperature corrugated conduit to prevent rubbing against the metal edges of the body.
  • 8
    Reconnect all connectors, reconnect the battery negative terminal, turn the ignition ON, use the diagnostic tool to clear the fault code, and perform an SRS system self-diagnosis.
  • 9
    Perform a road test or simulated vibration test to confirm the fault code does not recur. Verify the instrument panel airbag warning light turns off normally.
Real-World Cases
BYD DTC AI Analysis

Qin EV450 left rear impact sensor fault after wading

✓
A 2018 BYD Qin EV450 came in with the airbag warning light on the instrument panel constantly on. Connected a VDS diagnostic scanner and retrieved DTC B16DF-00 (left rear impact sensor disconnected). Inspection found the left rear door had been exposed to water. Removed the left rear sill trim panel and found the impact sensor connector had visible water stains and copper oxide corrosion inside. Cleaned the connector terminals, dried the wiring harness with compressed air, applied waterproof sealant and reconnected the plug. Cleared the fault code and the system returned to normal operation.
BYD DTC AI Analysis

Loose sensor connection on BYD Qin 100 after accident repair

✓
2017 BYD Qin 100. The SRS warning light illuminated following right rear collision repairs. Diagnosis revealed DTC B16DF-00. Inspection found the left rear impact sensor connector was not fully seated during the repair disassembly, causing an intermittent connection from driving vibrations. Reseated connector and installed a retaining clip, then secured the wiring harness routing with cable ties. Fault resolved.
BYD DTC AI Analysis

Suspected B16DF-00 high-voltage battery contact fault case

✓
An EV reported DTC B16DF-00. The technician suspected abnormal resistance at the high-voltage battery front-end contacts and recommended checking the battery balancing status and front-end contact connections. Note: This case differs from the standard SRS sensor definition, possibly due to model year variations in DTC definitions or a false report by the battery management system under specific conditions.
Original source ↗
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.