AU
B162A-00

DTC B162A-00 indicates an abnormal left front seat side airbag ignition circuit resistance of 0 ohms, representing a short-to-ground fault — Seal U

Safety System

DTC B162A-00 indicates an abnormal left front seat side airbag ignition circuit resistance of 0 ohms, representing a short-to-ground fault.

Normal airbag inflator resistance is 2.0-3.0 Ω.

A 0 Ω reading means the ignition circuit shorts to the vehicle body ground.

Potential causes include an internal airbag module short circuit, damaged wiring harness insulation shorting to ground, or shorted connector terminals.

This fault causes the SRS system to detect a risk of accidental ignition or deployment failure.

Consequently, the SRS system disables the airbag's collision protection function and illuminates the airbag warning light on the instrument cluster.

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Seat side airbag igniter internal short circuit (short circuit in airbag module internal bridge wire or damp propellant)
  • 2The wiring harness under the seat or on the side of the backrest shorts to the metal frame due to damaged insulation from long-term adjustment friction.
  • 3Water ingress, oxidation, corrosion, or bent pins at the seat side airbag connector (usually located under or beside the seat) causing a short circuit between the positive and negative terminals.
  • 4Internal fault in the SRS control unit sampling circuit causing a false low resistance fault.
  • 5Vehicle wading or directly spraying the side of the seat with a high-pressure water jet during a car wash caused water ingress and a short circuit in the connector.
What To Do
  • 1
    Safety preparation: Turn off the ignition, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS backup power supply capacitor and prevent accidental airbag deployment.
  • 2
    Freeze frame: Use the BYD VDS diagnostic tool to read the fault freeze frame data. Record environmental parameters such as vehicle speed, temperature, and voltage at the time of the fault to confirm whether the fault is intermittent.
  • 3
    Visual inspection: Remove the left front seat assembly. Closely inspect the seat back side airbag label area and the wiring harness under the seat for wear, pinching, damaged insulation, water ingress, or signs of modification.
  • 4
    Resistance measurement: Disconnect the SRS ECU connector (located at the lower center console or center tunnel). Use a multimeter to measure the resistance of the left front seat side airbag circuit (refer to the workshop manual for pin assignments). Normal resistance is 2.0-3.0 Ω. A reading close to 0 Ω confirms a short circuit.
  • 5
    Section isolation: Disconnect the seat side airbag connector. Measure the resistance between the two airbag assembly terminals (to check for an internal short circuit) and measure the resistance to ground on the wiring harness side (to check for a short to ground).
  • 6
    Insulation test: Use a megohmmeter to measure the insulation resistance between the wiring harness and body ground. The standard value must be greater than 1 MΩ.
  • 7
    Repair/Replace: If the airbag has an internal short circuit, replace the entire seat side airbag module (non-repairable). If the wiring harness is damaged, repair it and install corrugated conduit. Adjust the harness routing to prevent interference throughout the full seat fore-and-aft adjustment range.
  • 8
    System verification: Restore connections, install the battery, turn the ignition ON, use VDS to clear the fault code, and perform an SRS system self-check (wait 30 seconds with the vehicle stationary). Verify B162A-00 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat rail adjustment caused wiring harness to chafe and short circuit

✓
2018 BYD Qin EV450, airbag warning light on. Read DTC B162A-00. Removed and inspected the left front seat and found the side airbag wiring harness pinched at the frontmost position of the seat track. Long-term front/rear seat adjustment had worn through the insulation, exposing copper wires that contacted the metal seat frame and shorted to ground. Repair: Repaired the damaged harness, wrapped it with high-temperature tape, and re-secured the harness routing. Added cable clips at both ends of the seat track to provide enough slack during adjustment and prevent contact with metal parts.
BYD DTC AI AnalysisFrom Chinese market (translated)

Water ingress during car washing caused the connector to short circuit.

✓
A 2019 E1 developed fault code B162A-00 after a car wash in wet weather. Inspection found the left front seat side airbag connector (near the carpet at the seat base) had an aged seal. Water got into the connector during high-pressure washing, shorting the terminals. The fault was intermittent—disappearing after drying out but returning after subsequent washes. Fix: Replaced the connector seal, cleaned and dried the terminals, applied conductive anti-corrosion grease, and repositioned the wiring harness away from low spots where water collects.
BYD DTC AI AnalysisFrom Chinese market (translated)

Short circuit in seat side airbag igniter

✓
A 2017 Qin 100 with no accident history had the airbag warning light suddenly illuminate on the instrument cluster. VDS displayed DTC B162A-00. Removed the left front seat side airbag module (located on the side of the seat backrest) and disconnected the connector. Measured 0.2Ω resistance between the airbag component terminals, confirming a short circuit in the internal igniter bridge wire. Suspected moisture ingress into the airbag propellant or a manufacturing defect. Repair: Replaced the left front seat side airbag assembly (the complete airbag module must be replaced and cannot be repaired separately). After replacement, performed system configuration and self-check.
BYD DTC AI AnalysisFrom Chinese market (translated)

Installing seat covers caused the connector to come loose and short-circuit.

✓
A 2018 Qin EV450 developed a fault after the owner fitted full-coverage seat covers. The technician found that forced pulling during installation had loosened the seat side airbag connector (yellow plug). The force deformed the internal terminals, causing them to touch and create a short circuit. The seat cover clips had also secured the wiring harness too tightly, restricting normal movement. Reinstalled and locked the connector. Replaced the deformed terminals. Adjusted the wiring harness length to prevent strain during seat adjustment. Advised the owner to use seat covers with dedicated airbag cutouts.
Other Seal U 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]