AU
B162B

DTC B162B indicates the SRS (Supplemental Restraint System) control module detects the driver-side side airbag (typically the seat side airbag or side curtain airbag) igniter (squib) resistance is below the system threshold (typically <1 — Atto 8

Safety System

DTC B162B indicates the SRS (Supplemental Restraint System) control module detects the driver-side side airbag (typically the seat side airbag or side curtain airbag) igniter (squib) resistance is below the system threshold (typically <1.0Ω or below the standard range of 2.0-3.0Ω).

This fault indicates a short-circuit risk in the wiring or airbag assembly.

The system enters safety mode to prevent accidental airbag deployment or failure.

Triggering this fault disables the affected airbag circuit.

The airbag may fail to deploy during a side-impact collision, severely compromising occupant protection.

Additionally, a continuously illuminated SRS warning light indicates the entire airbag system may operate in a degraded protection mode.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Airbag wiring harness under the driver's seat worn or pinched, causing a short to ground: Frequent forward and backward seat movement can wear through the insulation on the yellow airbag wiring harness near the seat slide rail, causing the wire to directly contact the vehicle body metal.
  • 2Short circuit in airbag connector (yellow plug) internal terminals: Water ingress, oxidation, corrosion, or terminal deformation causes abnormal contact between positive and negative terminals, resulting in abnormally low resistance.
  • 3Internal short circuit in the driver side side airbag assembly: A short circuit in the airbag igniter internal bridge wire or pyrotechnic charge causes the resistance value to drop far below the standard value (<1.0Ω).
  • 4Seat modification or added accessories causing wiring faults: Installing aftermarket seat heating pads, massage pads, or seat covers pierces or crushes the airbag wiring harness, causing a short circuit between wires.
  • 5SRS control module internal detection circuit fault: A faulty A/D converter or monitoring chip in the control module causes a false low resistance reading (rare; rule out wiring faults before considering this).
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Initial inspection: Use the diagnostic tool to read all fault codes and freeze frame data. Confirm B162B is a current fault, not a history fault. Check the driver's seat side airbag yellow connector (located on the outer side of the seat backrest or the side of the seat cushion) for looseness, water ingress, or obvious damage.
  • 3
    Wiring insulation test: Disconnect the airbag connector. Use a multimeter to measure the resistance from both terminals on the wiring harness side (ECU side) to body ground. The normal value is >1MΩ (infinite). If the resistance is low, inspect the wiring harness under the seat for wear or damaged insulation. Focus on the seat slide rail mounting points and the wiring harness retaining clips.
  • 4
    Component resistance measurement: After disconnecting the airbag connector, directly measure the resistance between the two terminals of the airbag assembly (airbag side). The normal range is 2.0–3.0 Ω (1.5–3.0 Ω on some models). If the measured resistance is <1.0 Ω or close to 0 Ω, the airbag inflator has an internal short circuit. Replace the driver side airbag assembly.
  • 5
    Wiring harness repair: If the wiring harness is worn and shorted, repair the damaged wiring (use waterproof insulating tape or replace the wiring harness). Leave sufficient slack in the wiring harness throughout the full seat travel range. Re-secure the harness to the seat frame clips to prevent contact with metal edges.
  • 6
    System verification: Reconnect all connectors, reconnect the battery, and use the diagnostic tool to clear the fault code. Perform an SRS system self-diagnosis and confirm B162B does not return. Finally, move the seat forward and backward, then read the data stream again to confirm the resistance remains stable within the normal range.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Worn seat rails caused a short circuit in the wiring harness on the BYD Song Pro.

✓
A 2020 BYD Song Pro DM with 30,000 km on the odometer showed an airbag warning light on the instrument cluster. Retrieved DTC B162B (driver airbag resistance too low). Inspection found worn insulation on the yellow wiring harness beneath the driver's seat at the front-most position of the slide rail, with the copper wire contacting the seat frame and causing a short to ground. Repaired by wrapping the damaged harness, rerouting the wiring, adding protective sleeving, and installing additional harness retaining clips at the slide rail to prevent recurrence. After clearing the DTC, resistance returned to normal at 2.3 Ω.
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat modification caused airbag fault in BYD Tang EV

✓
The owner of a 2021 Tang EV reported the airbag warning light illuminated after installing an aftermarket seat ventilation system. The scan tool displayed DTC B162B. Inspection found the installers had not disconnected the battery when removing the seats, and had routed the ventilation hoses over the airbag harness, pressing on it and causing an internal short. After removing the aftermarket components, the airbag module resistance measured normal, but the harness side showed 0.5 Ω to ground. Replaced the seat wiring harness; fault cleared. Always disconnect the negative battery terminal for at least 90 seconds before removing or installing any seat.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Yuan EV airbag connector corroded due to water ingress

✓
My 2019 BYD Yuan EV threw a B162B fault code after I drove through deep water during a heavy rain. I found obvious water stains and verdigris inside the driver’s seat side airbag connector (under the seat), causing a micro-short between the terminals (resistance 0.8Ω). I cleaned the connector terminals with electronic contact cleaner, blow-dried them, applied conductive protectant, and replaced the waterproof seal. I also checked the floor drain holes for blockages. After the repair, the resistance returned to 2.1Ω.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin Pro airbag module internal short circuit

✓
2020 BYD Qin Pro petrol variant, no accident history. The instrument cluster suddenly displayed an airbag warning. Retrieved fault code B162B. Measured the seat wiring harness (infinite resistance to ground) as normal, but direct measurement across the airbag unit terminals showed only 0.3Ω. Diagnosed an internal short circuit in the airbag igniter. Replaced the driver's side airbag (seat-integrated type) and cleared the fault. The cause may be a batch quality defect within the airbag or long-term vibration causing the internal bridge wire to fracture and short to ground.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Han EV false alarm: loose connection

✓
The 2022 Han EV intermittently logged DTC B162B, and the warning light sometimes went out while driving. Diagnosis found the driver seat airbag connector was fully seated, but the internal terminal spring clips lacked sufficient tension. This caused contact resistance to momentarily drop below 1.0Ω during vehicle vibration, triggering the fault. Fix: use a dedicated pin removal tool to adjust the spring clip angle and increase contact pressure, or replace the connector terminals. After the repair, one week of continuous monitoring showed no recurrence.
Other Atto 8 Fault Codes
B1108For 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.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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.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.
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]