AU
B162B-00

DTC B162B-00 indicates the airbag control unit (SRS ECU) detects the driver side airbag (located on the side of the driver seat) igniter circuit resistance is below the system threshold (normal range: 2 — Atto 3

Safety System

DTC B162B-00 indicates the airbag control unit (SRS ECU) detects the driver side airbag (located on the side of the driver seat) igniter circuit resistance is below the system threshold (normal range: 2.0-5.0Ω; low resistance indicates a value below the lower limit or a near short circuit).

Electrically, this indicates an abnormally low-resistance path in the circuit.

Potential causes include a wiring short to ground, an internal short circuit in the airbag module, or abnormal connector conduction.

This fault causes the SRS system to classify the driver side airbag as unsafe.

During a collision, excessive current may prevent the igniter from deploying the airbag.

Additionally, a risk of accidental deployment (non-collision deployment) exists.

Consequently, the system illuminates the instrument cluster airbag warning light and may disable the entire airbag system, severely compromising occupant side-impact protection.

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Driver's seat side airbag wiring harness connector (usually located under the seat) is loose, oxidized, or has water ingress, causing abnormal continuity or abnormally low contact resistance between terminals.
  • 2Internal short circuit in the seat side airbag igniter (inflator) due to internal resistance wire insulation failure from aging, moisture ingress, or a manufacturing defect.
  • 3Damaged seat wiring harness insulation causes a short to body ground. Frequent seat adjustments typically cause long-term friction between the harness and the metal frame.
  • 4Internal short circuit in the clock spring (spiral cable); short circuit in the conductive disc inside the rotary connector connecting the steering wheel to the main body wiring harness.
  • 5SRS control unit internal detection circuit fault falsely reporting a low resistance value (relatively rare; confirm after ruling out preceding wiring issues).
What To Do
  • 1
    Safety preparation: Turn the vehicle power mode to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS system backup power and prevent accidental airbag deployment during repair.
  • 2
    Visual inspection: Inspect the SRS wiring harness connector (KJ10) under the driver's seat for looseness, water ingress, corrosion, or deformed pins. Inspect the wiring harness near the seat rail for wear or damaged insulation.
  • 3
    Resistance measurement (static): Disconnect the airbag module connector. Use a digital multimeter to measure the resistance between the terminals on the airbag module (normal value: 2.0-5.0Ω). If the resistance is too low, replace the airbag module.
  • 4
    Insulation measurement: Measure the resistance from wiring harness terminals KJ10-2 (B/Y wire) and KJ10-1 (Y/L wire) to body ground. The normal value is greater than 1 MΩ. If the resistance is too low, it indicates a short to ground in the wiring harness. Repair the wiring harness.
  • 5
    Wiring harness continuity check: Measure the continuity of the wiring harness between the SRS ECU and the seat connector. Verify no short or open circuits. Focus inspection on the bent section of the wiring harness under the seat.
  • 6
    Replacement verification: Connect a known-good driver-side airbag module or dedicated simulator. Clear and reread the fault codes. Check if the fault transfers to determine whether the module or the wiring harness is faulty.
  • 7
    Repair and verification: Based on the inspection results, replace the faulty airbag module, repair the damaged wiring harness, or replace the clock spring. Restore all connections and secure the connectors. Reconnect the battery. Use the diagnostic tool to clear the fault code and perform an SRS system self-test. Confirm B162B-00 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Oxidation of the seat side airbag wiring harness connector caused poor contact.

✓
**Symptoms:** The airbag warning light on the dashboard stays illuminated constantly. The diagnostic tool reads DTC B162B-00. The vehicle has no collision history. **Diagnostic procedure:** Disconnected the battery negative terminal and checked the side airbag wiring harness connector (KJ10) under the driver's seat. Found the terminals had slight oxidation and were loose. The resistance from the harness end to ground measured abnormally low. **Repair:** Cleaned the connector terminals with electronic cleaner to remove the oxidation, applied conductive protectant and reconnected firmly. Cleared the DTC and the system returned to normal.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat adjustment caused the wiring harness to chafe and short to ground.

✓
Symptoms: Airbag warning light on steady after vehicle startup, following seat leather replacement. DTC B162B-00 stored. Diagnosis: Disconnected airbag module connector, measured resistance from harness-side terminals KJ10-2 and KJ10-1 to chassis ground. Reading only several tens of ohms (specification: >1 MΩ). Determined harness short to ground. Further inspection found the harness chafed by the seat frame edge during seat adjustment, insulation damaged. Resolution: Repaired the harness (re-wrapped insulation). Re-routed harness and added protective sleeving to prevent interference with the seat frame. Fault cleared.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Abnormal internal resistance in driver side airbag module

✓
Symptoms: No accident history or modifications; however, the SRS warning light intermittently illuminates, displaying DTC B162B-00. The code returns repeatedly despite multiple clearing attempts. Diagnosis: Conducted a substitution test. Disconnected the original airbag module and connected a new driver's seat side airbag module. Cleared the fault code and waited 20 seconds; the code did not return. This confirmed an internal resistance fault in the original module (internal short circuit or resistance drift). Solution: Replaced the driver's seat side airbag module with a new unit. Ensured the module was level during installation and tightened to the specified torque (typically 9-11Nm). Cleared the fault code and performed system configuration after fitting. Fault completely resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short in clock spring caused intermittent fault

✓
Symptoms: Airbag warning light occasionally flashes or comes on when turning the steering wheel. Sometimes goes off automatically when stationary. DTC: B162B-00. Diagnosis: Removed the steering wheel and inspected the connector between the clock spring (spiral cable) and the airbag harness. The connector was loose, and the terminals had slight burn marks. Measured resistance in this circuit section—readings fluctuated, with the minimum value below the normal range. Solution: Replaced the clock spring assembly (internal conductive disc shorted and burnt). Securely reconnected all connectors. After repair, rotated the steering wheel multiple times; the fault did not return.
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. Sources: [1]