AU
B16B000

DTC B16B000 indicates the airbag electronic control unit (SRS ECU) detects an internal system fault or a deployment circuit abnormality — Atto 3

Safety System

DTC B16B000 indicates the airbag electronic control unit (SRS ECU) detects an internal system fault or a deployment circuit abnormality.

This fault may involve an internal ECU processor fault, a power/ground abnormality, a CAN communication fault, or, more commonly, the driver-side airbag deployment circuit resistance falling outside the calibrated range (normal 2.0-3.0 Ω).

When the ECU detects high circuit resistance (>5 Ω), an open circuit, low circuit resistance (<1 Ω), or a short circuit, it sets this code and illuminates the instrument cluster airbag warning lamp.

The system enters fail-safe mode, and the airbag may fail to deploy during a collision.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Broken internal ribbon cable or poor contact within the clock spring (spiral cable): Repeated steering wheel rotation wears the internal flat cable, causing an intermittent or permanent open circuit.
  • 2Airbag module ignition circuit fault: Broken internal clock spring after collision, connector oxidation, or internal module open circuit, causing abnormal circuit resistance.
  • 3Wiring harness water corrosion: Waterproofing failure in the under-seat or floor wiring harness allows water to enter the connector. This produces copper corrosion, increasing contact resistance or causing signal interference.
  • 4Improper modification or repair: Incorrect steering wheel removal and installation causing clock spring misalignment, over-stretching of the airbag wiring harness, or damage to the connector locking tab.
  • 5Internal SRS ECU fault: Damaged power supply chip, internal memory data error, or burnt ignition driver circuit (common in accident vehicles or under abnormal voltage conditions).
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS ECU capacitor. Do not work on the airbag system with the ignition switch ON.
  • 2
    Diagnostic tool check: Use the BYD VDS2000 or ED400 to read all fault codes and freeze frame data. Determine if the fault is historical or current. Check the 'DAB Resistance' (driver airbag resistance) value in the data stream.
  • 3
    Visual inspection: Check the yellow connector (airbag-specific colour) under the steering wheel for looseness or backed-out terminals, check the clock spring for visible damage, and verify the wiring harness waterproof plugs under the seat and on the floor are intact.
  • 4
    Circuit resistance measurement: Use a dedicated airbag system tester or a multimeter connected in series with a 2kΩ resistor to measure the driver airbag circuit resistance (disconnect the ECU connector and measure the resistance on the wiring harness side; normal resistance is 2.0-3.0Ω). Never use a multimeter ohm setting to directly measure the airbag squib.
  • 5
    Isolation test: Disconnect the pocket connector and measure resistance on both sides of the clock spring to determine if the clock spring or the airbag module is faulty. If resistance is infinite, replace the clock spring. If the module side shows an open circuit, replace the airbag assembly.
  • 6
    Special handling for flooded vehicles: If you find wiring harness corrosion, replace the entire harness section; do not just clean the connector. Rewrap the harness using waterproof tape (3M Scotch 33+) and heat-shrink tubing. Install a waterproof sleeve if necessary.
  • 7
    ECU matching and calibration: If replacing the SRS ECU or airbag module, use the diagnostic tool to execute the 'Replace ECU' or 'Airbag Configuration' function, write the VIN and configuration code, and perform sensor zero-point calibration.
  • 8
    Verify clearance: Reconnect the battery, start the vehicle, and confirm the airbag warning light turns off after the self-check (within 6 seconds). Turn the steering wheel lock-to-lock and perform a road test to confirm the intermittent fault does not recur.
Real-World Cases
BYD DTC AI Analysis

BYD Qin PLUS DM-i clock spring poor contact

✓
Symptoms: Dashboard airbag warning light constantly on with audible chime. Diagnosis: VDS2000 retrieved DTC B16B000. Measured driver airbag circuit resistance at 5.8Ω (out of specification). On disassembly, found the white clock spring connector had poor contact with oxidised pins. Repair: Cleaned connector pins, applied conductive paste and reassembled. Resistance returned to 2.4Ω, fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro DM module fault after accident repair

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Symptoms: After front collision repairs, the airbag warning light stayed on constantly and could not be cleared. Diagnosis: DTCs B16B000 and B16B100 stored. Measured infinite resistance (open circuit) at the driver-side airbag module. The collision impact fractured the clock spring inside the airbag. Repair: Replaced the driver-side airbag assembly (EQ-5820100), performed ECU matching and system calibration. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM-i wiring harness corrosion due to water ingress

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Symptoms: After water ingress, the dashboard displayed a "Check Airbag System" warning. Diagnosis: Retrieved DTC B16B000. Inspected the wiring harness connector under the seat and found the waterproof seal had detached. Internal water staining and verdigris were present, with resistance fluctuating between 2–10 Ω. Resolution: Replaced the driver's side airbag wiring harness (clock spring to ECU section), rewrapped the connections with waterproofing, and fitted a waterproof protective sleeve.
Original source ↗
BYD DTC AI Analysis

Modified steering wheel caused a fault in a BYD Han EV.

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Symptoms: After fitting an aftermarket carbon fibre steering wheel and driving 500 km, the airbag light came on. There were abnormal noises when turning the wheel at a standstill. Diagnosis: DTC B16B000. Disassembly revealed that excessive pulling on the airbag harness had broken the yellow plug locking tab, and that the clock spring locating pin was misaligned, damaging the clock spring. Resolution: Replaced the OE clock spring (HCE-5820100), repaired the harness plug, and refitted the original steering wheel.
Original source ↗
BYD DTC AI Analysis

BYD Yuan EV360 intermittent fault

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Symptoms: Warning light occasionally illuminates on cold start and turns off automatically after 10–15 minutes of driving. Diagnosis: Historic DTC B16B000. Circuit readings normal when warm. Determined poor contact in clock spring at low temperatures. Disassembly revealed dried internal grease, causing poor contact between slip ring and brush when cold. Repair: Replaced clock spring assembly. Fault completely resolved.
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.