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 — Atto 3

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 Atto 3 indicates the SRS airbag control unit has lost communication with the left rear impact sensor. This is a medium-severity fault that can disable side-impact detection and affect side airbag or curtain airbag operation. Common causes include damaged wiring, a loose connector, or water-related corrosion. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Left rear impact sensor wiring harness broken or crushed. Long-term vibration fractures copper wires, especially at harness bends routed through the door hinge or inside the sill trim panel.
  • 2Loose sensor connector, backed-out terminal, or water ingress and corrosion. Poor sealing commonly causes terminal oxidation after driving through water or washing the vehicle.
  • 3Internal accelerometer damage or circuit fault in the crash sensor causes no signal output.
  • 4SRS control unit internal detection circuit fault preventing correct sensor signal identification (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, and confirm the vehicle speed, timestamp, and other information at the time of the fault.
  • 2
    Switch off the ignition, disconnect the battery negative terminal, and wait at least 90 seconds for the SRS system high-voltage capacitor to fully discharge.
  • 3
    Remove the left rear interior trim panel (lower C-pillar trim panel or left rear 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 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 (< 1 Ω), and check the insulation resistance to ground (> 1 MΩ).
  • 6
    Measure the sensor body resistance (refer to the workshop manual for the 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 metal body edges.
  • 8
    Reconnect all connectors, reconnect the battery negative terminal, turn on the ignition, 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 Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.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.
Common problems reported for Atto 3 →Atto 3 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.