AU
B16DF00

This DTC indicates an interrupted communication link between the airbag control unit (SRS ECU) and the left rear crash sensor — Atto 3

Safety System

This DTC indicates an interrupted communication link between the airbag control unit (SRS ECU) and the left rear crash sensor.

The left rear crash sensor typically utilizes a MEMS capacitive accelerometer and mounts on the left rear side panel (C-pillar area) to monitor left rear collision acceleration.

During the ECU initialization self-check or a drive cycle, if the ECU fails to detect the sensor bias voltage (normally a 2.5V reference voltage at a 2-3kΩ equivalent resistance), detects infinite circuit resistance, or reads a continuous high or low signal line voltage exceeding the threshold, it registers a 'not connected' state.

This fault may prevent the left rear side airbag and curtain airbag from deploying correctly during a collision.

The ECU simultaneously illuminates the airbag warning lamp and enters fail-safe mode (some models disable the entire side airbag circuit).

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Sensor wiring harness connector loose, terminal backed out, or oxidized due to water ingress (common if not fully seated after rear seat removal/installation or C-pillar trim panel repair).
  • 2Open circuit due to physical damage to the wiring harness (sill trim panel pinching the wire, or a detached harness retaining clip allowing the harness to rub against a sharp body edge, breaking the copper conductor)
  • 3Internal damage to the crash sensor (cracked piezoelectric element, internal resistance drift outside the standard 1.8-3.5kΩ range)
  • 4Installation of a mismatched aftermarket sensor after accident repairs (incorrect configuration code, or 2-wire/3-wire mismatch resulting in an incompatible communication protocol).
  • 5Left rear sill wiring harness corroded from prolonged water immersion (common in flooded vehicles, causing green corrosion on connector terminals or internal open circuits)
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 3 minutes to discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Fault Confirmation: Use the genuine BYD diagnostic tool (ED400/ED600) to read the fault code. Verify B16DF00 is a Current DTC and record the freeze frame data.
  • 3
    Location and inspection: Remove the left rear C-pillar interior trim panel or left rear door sill trim panel to locate the left rear crash sensor (usually positioned above the left rear door striker or on the side panel reinforcement beam).
  • 4
    Basic measurement: Disconnect the sensor connector. Measure the resistance between the two terminals on the sensor itself (standard: 2-3kΩ). If the resistance is infinite or 0Ω, replace the sensor.
  • 5
    Wiring harness inspection: Measure the continuity (< 1Ω) and insulation resistance to ground (> 10MΩ) of the wiring between the sensor connector and the SRS ECU (usually located under the center console). Closely inspect the bends in the sill wiring harness.
  • 6
    Repair procedure: Repair the damaged wiring harness (soldering + heat-shrink tubing) and re-wrap with waterproof tape. If the connector shows oxidation, clean with electronic contact cleaner and apply conductive grease.
  • 7
    Replacement and installation: If the sensor is damaged, replace it with a genuine part (part number must match the VIN). Tighten to 8-10 N·m during installation to prevent vibration loosening.
  • 8
    System reset: Connect the battery, use the diagnostic tool to clear the fault code, and perform the SRS system self-test (some models require crash sensor configuration learning or online calibration).
  • 9
    Verification test: Road test the vehicle for 5-10 km, including bumpy roads. Confirm the SRS warning lamp does not illuminate and the diagnostic tool shows no history fault codes.
Real-World Cases
BYD DTC AI Analysis

Yuan PLUS EV rear seat removal and installation caused a loose sensor connector.

✓
The SRS warning light stayed on. The scan tool read DTC B16DF00. Inspection found the sensor connector inside the left rear C-pillar trim panel was loose. The wiring harness had been pulled during rear seat removal and installation, causing a poor connection. Sensor resistance was infinite. Reconnected the connector, secured the harness routing with cable ties, cleared the fault code, and the system returned to normal.
Original source ↗
BYD DTC AI Analysis

Qin Pro DM door sill trim pinched wire, causing wiring harness chafing and short circuit

✓
SRS warning light illuminated intermittently while driving, with stored DTCs B16DF00 and B16E011. Inspected left rear sill trim and found wiring harness pinched by a retaining clip, insulation worn through exposing copper strands that shorted to body ground. Repaired damaged harness and adjusted routing, replaced deformed sensor mounting bracket. Monitored for one week with no recurrence.
Original source ↗
BYD DTC AI Analysis

Incorrect aftermarket sensor configuration on Song PLUS after accident repair

✓
After rear-end collision repair on the left rear, the SRS warning light stayed on. Pulled DTC B16DF00. The shop had installed an aftermarket 2-wire sensor; the vehicle needs a 3-wire accelerometer. Sensor resistance was only 0.8 kΩ, well below spec. Replaced it with the correct OEM sensor and ran the configuration learn procedure using a scan tool. Fault resolved.
Original source ↗
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.