AU
B160B

DTC B160B indicates the SRS (Supplemental Restraint System) control unit detects the driver frontal airbag (DAB) igniter (squib) circuit resistance is below the calibrated threshold (typically <1 — Atto 3

Safety System

DTC B160B indicates the SRS (Supplemental Restraint System) control unit detects the driver frontal airbag (DAB) igniter (squib) circuit resistance is below the calibrated threshold (typically <1.5Ω; standard range is 2.0±0.3Ω).

This active fault indicates an abnormally low-resistance path in the circuit.

A partial short circuit, an internal turn-to-turn short in the igniter, or a wiring harness short to ground can cause this condition.

The low resistance abnormally increases the airbag circuit current, creating a risk of unintended airbag deployment.

Alternatively, during a collision, the excessive current may trigger the ACU protective cutoff and prevent normal deployment.

When this DTC triggers, the SRS system typically enters fail-safe mode and disables the driver-side airbag.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Turn-to-turn short circuit or wear in the clock spring (spiral cable) internal coil, reducing effective resistance. This is a common failure point on BYD models (especially Tang and Song series).
  • 2Internal short circuit in the driver airbag module (DAB) igniter, or moisture in the pyrotechnic charge causing resistance drift; typically occurs after vehicle water ingress or in high-temperature, high-humidity environments.
  • 3Airbag wiring harness short to ground or short to power. Common causes include a damaged wiring harness sleeve below the steering wheel, pinched wiring during steering wheel modification, or backed-out terminal pins.
  • 4SRS control unit (ACU) internal sampling circuit fault or reference resistor drift causing falsely low resistance measurements. Rule out by cross-checking.
  • 5Connector water ingress or terminal corrosion (e.g., poor sealing under the steering wheel on Yuan EV and Qin models) creates a parallel resistance path, reducing total resistance.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 90 seconds (to allow the ACU capacitor to fully discharge). Do not measure the airbag terminals directly with a multimeter set to ohms (the test current may trigger airbag deployment).
  • 2
    Initial diagnosis: Connect the VDS or BYD dedicated diagnostic tool, read the fault code status (current/history), record the resistance value in the freeze frame data (e.g., 0.8Ω or 1.2Ω), and confirm fault persistence.
  • 3
    Visual inspection: Check the wiring harness sleeve below the steering wheel and the clock spring connector (usually yellow) for damage, signs of water ingress, or modifications. Check the airbag terminals for oxidation.
  • 4
    Segmented resistance measurement: Disconnect the clock spring from the airbag. Use a dedicated airbag tester or connect a 2Ω dummy load in series. Measure the airbag module resistance and the wiring harness circuit resistance separately to locate the faulty section.
  • 5
    Component isolation test: Move the driver airbag module to the front passenger position (for testing only). If the fault code changes to B160C (front passenger resistance too low), the airbag module is faulty. If the code remains B160B, check the clock spring or wiring harness.
  • 6
    Clock spring inspection: Measure the clock spring resistance at different rotation angles. If the resistance fluctuates or drops below 1.0Ω while turning the steering wheel, this indicates an internal short circuit. Replace the clock spring.
  • 7
    Repair and verification: After replacing the faulty component, use the diagnostic tool to perform 'Crash Sensor Calibration' and 'System Self-test'. Confirm the resistance value returns to within 2.0±0.3Ω. Clear the fault code and perform an ignition-on cycle test.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Tang DM clock spring internal short circuit resulting in 0.9Ω resistance.

✓
2021 Tang DM. The dash showed an 'Airbag Fault'. Retrieved DTC B160B. Live data indicated the driver's airbag resistance at 0.9Ω. Disassembled the steering wheel and found slight water ingress on the clock spring connector. Removed the clock spring and measured the resistance: 1.2Ω at rest, dropping to 0.6Ω when turning the steering wheel. Determined the internal flat cable insulation had worn, causing a short. Installed a genuine clock spring (part number: KE-4135100). Resistance returned to 2.1Ω. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Song MAX airbag connector corroded after wading

✓
2019 Song MAX. After a typhoon, the airbag warning light stayed on constantly and stored DTC B160B. Inspection found muddy water intrusion in the wiring harness connector below the driver-side A-pillar (airbag circuit branch). The terminals showed green oxidation, causing approximately 0.5Ω parallel resistance. Cleaned terminals using electronic contact cleaner, applied conductive anti-corrosion grease, and replaced the waterproof seal ring. Resistance returned to normal. Recommend checking the door weatherstrip drain holes for blockages.
BYD DTC AI AnalysisFrom Chinese market (translated)

Modified steering wheel on Yuan EV crushed the wiring harness

✓
2019 BYD Yuan EV. One week after the owner fitted a racing steering wheel, DTC B160B set. Inspection found the aftermarket adapter hub was too thin, causing the original airbag wiring harness to be excessively pinched at the steering wheel frame. This damaged the insulation and created a short to ground. Repaired the wiring harness and fitted a dedicated harness protection sleeve. After restoring the factory steering wheel, the fault cleared. Tip: When fitting an aftermarket steering wheel, make sure the clock spring and airbag wiring harness have enough clearance.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro ACU software falsely reporting low resistance

✓
2020 BYD Qin gasoline. Intermittent B160B. Measured airbag resistance: 2.0Ω (normal). Checked ACU software version: V1.2. Known issue: overly sensitive sampling algorithm threshold. Flashed ACU to V2.1 using VDS (ECU refresh), which lowers the resistance detection threshold lower limit to 1.2Ω. Fault did not return. This type of software fault needs confirmation by comparing with multiple vehicles from the same production batch.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short circuit in driver airbag igniter due to aging

✓
2019 Yuan, 80,000 km. DTC B160B persistent, resistance 1.0 Ω. Disconnected the clock spring and measured the airbag assembly directly; resistance remained low. Disassembled the airbag and found the insulation between the igniter bridge wire and housing had aged and broken down. Replaced the driver airbag assembly. Airbags are hazardous explosives—handle the old part in accordance with explosives transport regulations. Fault resolved. This fault occurs more frequently in high-temperature regions such as Hainan and Guangdong.
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. Sources: [1]