AU
B162C-00

DTC B162C-00 indicates the SRS (Supplemental Restraint System) control unit detects resistance exceeding the calibrated threshold in the driver side airbag ignition circuit — Atto 8

Safety System

DTC B162C-00 indicates the SRS (Supplemental Restraint System) control unit detects resistance exceeding the calibrated threshold in the driver side airbag ignition circuit.

The driver side airbag typically mounts in the side of the driver seat backrest or inside the door trim panel.

Normal circuit resistance ranges from 2-3 ohms; the fault threshold typically exceeds 3.5-4 ohms.

The SRS ECU monitors circuit integrity by sending a low-current signal through its internal detection circuit to the airbag igniter.

High-resistance connections (e.g., poor contact, loose harness connections, oxidation, or partial wire breaks) increase total circuit resistance, causing the ECU to register a high-resistance fault.

This fault severely compromises side-impact protection.

Excessive resistance limits current, potentially causing the driver side airbag to deploy late or fail to deploy during a collision.

The system illuminates the SRS warning lamp and may disable the entire airbag system, resulting in a complete loss of collision protection.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Fatigue fracture or poor contact in the under-seat wiring harness: Frequent forward and backward driver seat adjustment repeatedly bends the airbag wiring harness secured under the seat. This partially breaks the internal copper strands while leaving the insulation intact, creating a high-resistance connection.
  • 2Poor connector contact: Moisture, oxidation, or an incompletely engaged locking tab increases contact resistance at the seat side airbag connector (usually a yellow plug).
  • 3Improper modification or repair: Failure to fully seat the airbag connector during reinstallation after seat leather reupholstery, heating pad retrofitting, or accident repair, or the seat slide rail crushing and damaging the wiring harness.
  • 4Internal airbag assembly fault: Airbag igniter internal resistance wire aging or poor connection (less common; usually shows unstable or infinite resistance).
  • 5Improper wiring harness routing: A detached harness retaining clip allows the harness to stretch or rub against other components during seat movement, causing an intermittent open circuit.
What To Do
  • 1
    Safety preparation: Switch off the ignition, disconnect the 12V battery negative terminal, and wait at least 3 minutes (to fully discharge the SRS capacitor and prevent accidental airbag deployment).
  • 2
    Fault confirmation: Connect the dedicated BYD diagnostic tool (VDS or ED400), read the SRS system fault codes, confirm B162C-00 is a current fault and not a history fault, and record the freeze frame data.
  • 3
    Visual inspection: Remove the driver's seat side trim panel. Check if the airbag connector (yellow) is fully seated, the locking tab is engaged, and the terminals show oxidation or corrosion from water ingress.
  • 4
    Static resistance measurement: Disconnect the airbag connector. Use a digital multimeter to measure the airbag unit resistance (should be between 2 and 3 ohms). If normal, the fault is in the wiring harness. If the resistance is too high, replace the airbag assembly.
  • 5
    Harness continuity check: Measure harness resistance between the SRS ECU and the airbag connector. Resistance must be less than 1 ohm. Focus on the harness under the seat. Strip back the corrugated conduit to check for hidden breaks.
  • 6
    Dynamic test: With the diagnostic tool connected, move the seat forward and backward and monitor the data stream for resistance value fluctuations. If the resistance value changes with the seat position, confirm an intermittent open circuit in the wiring harness.
  • 7
    Repair and Replacement: Repair the broken wiring harness (solder and insulate with heat-shrink tubing) or replace the wiring harness assembly. Reroute the harness to ensure sufficient slack and prevent the seat slide rail from pinching it.
  • 8
    System reset: Connect all connectors, reinstall the seat, and connect the battery. Use the diagnostic tool to clear the fault code. Perform the SRS system self-check (conditions include vehicle speed at 0 and normal system voltage). Confirm the warning light turns off and the fault code does not return.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Long-term flexing caused an intermittent connection in the BYD Qin seat wiring harness.

✓
The SRS warning light stayed on with DTC B162C-00 stored. Found the wiring harness under the driver's seat had internal wire breaks but undamaged outer insulation, caused by repeated forward and backward seat adjustment. Resistance fluctuated between 5 and 8 ohms. Replaced the seat wiring harness assembly and repositioned the harness mounting points to increase slack, preventing excessive stretching during seat movement. After clearing the DTC, the system returned to normal.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro seat slide rail crushed wiring harness

✓
Owner reported the SRS warning lamp illuminating intermittently; scan revealed DTC B162C-00. Diagnosis found the seat rail mounting bolts overtightened, crushing the wiring harness beneath and causing partial fracture of the internal copper conductors. The airbag module tested normal, but circuit resistance fluctuated between 3 and 8 ohms. Fix: Rerouted the wiring to avoid the seat rail pinch point, replaced the damaged harness section, adjusted bolt torque, and fitted a protective sleeve to the harness. Fault rectified.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM connector not properly secured after collision repair

✓
After collision repair, the SRS warning light remained on with DTC B162C-00. Inspection found that the driver's seat had been removed and reinstalled. The side airbag connector plug was not fully inserted (locking clip not secured), causing high contact resistance (measured 4.5 ohms). Reorganized the seat wiring harness to eliminate any pinching or interference, reconnected the airbag connector and confirmed the locking click, then performed the SRS calibration, resolving the fault.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat modification caused poor contact on BYD e5

✓
The vehicle had no accident history, but B162C-00 set immediately after leather seat reupholstery. Inspection found the side airbag had been removed during the modification. The connector wasn't fully seated upon reinstallation, and the terminals showed slight oxidation. Repair: - Cleaned the connector terminals and applied conductive grease. - Correctly reinstalled the airbag module and restored factory wiring connections. - Cleared the fault code; self-test passed.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Intermittent loose connection in BYD Qin Pro wiring

✓
The SRS warning light came on intermittently and turned off automatically. We diagnosed the fault and found the under-seat wiring harness measured 2.5 ohms when stationary, but resistance increased above 6 ohms when sliding the seat fore and aft. We stripped back the harness sleeve and found a loose internal connection. We cut out the damaged wire section, resoldered it, insulated with heat-shrink tubing, and adjusted the harness mounting bracket to provide more slack. Multiple seat adjustment tests confirmed the fault was resolved.
Original source ↗
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]