AU
B16BD-00

DTC B16BD-00 indicates a LIN (Local Interconnect Network) bus communication fault between the Body Control Module (BCM) and the left front window motor — Atto 3

Safety System

DTC B16BD-00 indicates a LIN (Local Interconnect Network) bus communication fault between the Body Control Module (BCM) and the left front window motor.

Some early documents label this code as SRS-related; however, it actually indicates a loss of communication or abnormal signal voltage at the left front window motor (LHD Driver Door Motor).

The LIN bus uses a single-wire circuit (typically green/white) with a normal operating voltage of 9-11V.

The BCM sets this DTC if it fails to receive a response signal from the motor within the specified time, or if it detects a bus open, short to ground, or short to power.

This fault disables left front window operation and the anti-pinch function.

The BCM may also enter protection mode and cut power to the motor.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Shorted or burnt-out internal LIN transceiver chip in the left front window motor, pulling the bus voltage low (commonly 2-3 V).
  • 2Poor connection or break in the LIN wiring harness at the door hinge (repeated door opening and closing causes copper wire fatigue and breakage, leaving only a few strands connected)
  • 3Aged and failed motor connector waterproof rubber seal allows water ingress from rain or car washing, causing connector oxidation and a LIN line short to ground.
  • 4Blocked door drain hole causes accumulated water to soak the motor, resulting in corrosion or short circuit of the internal communication circuit.
  • 5Motor mechanical binding (rusted cable, mud and sand accumulation in the guide rails) causes excessive stall current; the BCM cuts off communication for protection and logs the fault.
What To Do
  • 1
    Connect the BYD VDS diagnostic tool, enter the BCM system to read fault codes, confirm whether B16BD-00 is a current or history fault, and record the freeze frame data.
  • 2
    Check the left front window motor power supply (constant 12V, connector pin 1) and ground (connector pin 2) to rule out basic circuit faults.
  • 3
    Disconnect the motor connector and measure the LIN line (pin 3) voltage. Normal voltage is 9-11V. If the voltage is below 5V, measure resistance to ground. Normal resistance is greater than 10kΩ.
  • 4
    Inspect the door hinge wiring harness sleeve, focusing on the LIN wire (green/white) for breaks or poor connections. If necessary, strip the sleeve to inspect the internal copper strands.
  • 5
    Remove the door trim panel and inspect the motor connector seal. Inspect the terminals for green oxidation or water stains. If present, clean the terminals, replace the waterproof sealing ring, and apply waterproof silicone grease.
  • 6
    Reconnect the connector and use an oscilloscope to measure the LIN bus waveform. Verify the data frame interval and waveform amplitude are normal, or replace with a test motor to verify.
  • 7
    If you suspect mechanical binding, measure the motor operating current: normal window raising and lowering current is 3-6A. If the current exceeds 12A and you detect a burnt smell, replace the window regulator assembly.
  • 8
    After repair or replacement, clear the fault code and perform the window anti-pinch initialization: raise the glass to the top and hold for 2 seconds, then lower it to the bottom and hold for 2 seconds. Verify normal operation.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM: Motor internal short circuit dragging down voltage

✓
2019 Qin Pro DM – driver's side window suddenly stopped working; the other three doors were unaffected. Scanned the BCM and found DTC B16BD-00 (left front window motor communication fault). Measured LIN line voltage at the motor connector: only 2.8V (normal 9–11V). Disconnected the motor connector, and the voltage recovered to 10.2V. Determined that the internal LIN chip in the motor had shorted, pulling the bus low. Replaced the left front window motor assembly (SA2H-6104210) and performed anti-pinch initialisation. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Water ingress and oxidation in the Han EV connector caused communication failure.

✓
2020 Han EV left front window stopped midway with a clicking noise, occurring frequently in wet weather. DTC B16BD-00 stored as both current and history. Power and ground tested normal. Oscilloscope check showed noise on the LIN bus waveform. Disassembly revealed green copper oxide inside the motor connector; the waterproof seal had aged and was leaking. Removed the oxidation, replaced the seal and applied waterproof silicone grease. The motor had minor water ingress, so replaced it (SC2E-6104210). Followed up for one week with no recurrence.
Original source ↗
BYD DTC AI Analysis

Song PLUS DM-i door water ingress burned out communication chip

✓
2021 Song Plus DM-i: Left front window wouldn't go up after a car wash. Scan tool showed B16BD-00 (lost communication with left front window motor). Removed the door trim and found blocked drain holes. Water had accumulated and soaked the motor. Measured LIN line-to-ground resistance at only 45 Ω (normal >10 kΩ), indicating the motor's internal communication chip had burned out. Unclogged the drain holes, dried the wiring harness, replaced the motor assembly, and installed a waterproof protective sleeve.
Original source ↗
BYD DTC AI Analysis

Tang DM intermittent poor contact in hinge wiring harness

✓
2018 Tang DM left front window malfunctions intermittently on rough roads; fault is intermittent. DTC B16BD-00 stored as intermittent. Power and earth normal; fault recurs when wiggling the harness. Stripped back the rubber boot at the door hinge and found the LIN wire (green/white) internal copper conductors 95% fractured, with only a minimal connection remaining, causing communication dropouts under vibration. Cut out the fractured section, soldered in a 0.5mm² automotive-grade jumper wire, sealed with heat-shrink tubing, then rerouted and secured the harness.
Original source ↗
BYD DTC AI Analysis

e5 ride-hailing vehicle motor mechanical seizure and locked rotor

✓
2017 BYD e5 (commercial vehicle). Left front window slowed then jammed; could be pushed manually, motor dead with a burning smell. Read DTCs B16BD-00 and B16BD-11 (motor circuit low voltage). Measured motor current at 14.5A (normal 3–6A), diagnosed mechanical binding (cable corroded). Replaced left front window regulator assembly (motor and cable, P/N SA2A-6104210), cleaned mud from the guide rails, and applied rubber protectant. Current dropped to normal 4.2A.
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.