AU
B163111

DTC B163111 indicates the SRS (Supplemental Restraint System) control module detects an abnormally low-resistance path to body ground (short to ground) in the front passenger side airbag squib circuit (typically the seat side airbag or curtain airbag) — Seal U

Safety System

DTC B163111 indicates the SRS (Supplemental Restraint System) control module detects an abnormally low-resistance path to body ground (short to ground) in the front passenger side airbag squib circuit (typically the seat side airbag or curtain airbag).

Under normal operating conditions, the airbag squib circuit resistance must remain around 2-3 Ω, and the insulation resistance to ground must exceed 1 MΩ.

The control module logs a short to ground when it detects circuit resistance approaching 0 Ω or current leaking to ground.

This fault prevents the side airbag from deploying during a side-impact collision, eliminating side-impact protection for the occupant.

The circuit abnormality also creates a potential risk of unintended deployment, although a short to ground typically causes a non-deployment failure rather than accidental triggering.

This fault constitutes a severe active safety system failure.

Remove the vehicle from service immediately until repaired.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Long-term chafing or pinching damages the airbag wiring harness insulation near the front passenger seat slide rail or B-pillar, causing the wire to directly contact the vehicle body metal.
  • 2Internal water ingress and oxidation in the under-seat airbag wiring harness connector (usually located at the seat-to-floor junction) caused by wading or improper cleaning, or misaligned or loose pins, resulting in a short to ground.
  • 3Internal short circuit in the front passenger side airbag module squib causes one of the two terminals to short to ground.
  • 4During vehicle modifications (such as adding seat heating, ventilation, leather trim, or audio upgrades), screws or clips pierce the wiring harness, or an improperly secured harness contacts sharp metal edges.
  • 5Improper airbag wiring harness routing after accident repairs causes dynamic interference with the seat adjustment mechanism, resulting in insulation wear.
What To Do
  • 1
    Safe power-down: Turn off the ignition switch, disconnect the 12V battery negative terminal, and wait at least 90 seconds (120 seconds for some models) to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Initial visual inspection: Check the airbag wiring harness connectors (usually marked yellow) under the front passenger seat, at the bottom of the B-pillar trim panel, and inside the door sill trim panel for obvious damage, signs of water ingress, pin corrosion, or loose connectors.
  • 3
    Disconnect the airbag module: Carefully remove the front passenger side airbag module (located on the outer side of the seat or inside the door panel) and disconnect its connector. Never use a multimeter to measure the airbag module terminals directly (test current may cause deployment). Measure only the wiring harness side.
  • 4
    Harness-to-ground resistance measurement: Use a high-impedance digital multimeter to measure the resistance between each pin on the harness-side connector and the vehicle body ground. The normal value should be greater than 1 MΩ; if the resistance is less than 1 Ω, a short to ground exists.
  • 5
    Section-by-section isolation check: Disconnect the intermediate connector along the wiring route (usually located below the B-pillar or under the seat). Measure each section to narrow down the fault area and determine whether the short circuit is in the seat section, B-pillar section, or instrument panel section.
  • 6
    Airbag module inspection: Use a dedicated SRS diagnostic tool or specified adapter to measure the resistance between the two airbag module terminals (normal: 2-3Ω) and the insulation to ground for each terminal. Replace the module if it has internal continuity to ground.
  • 7
    Wiring harness repair and replacement: Use waterproof heat-shrink tubing to insulate and repair the damaged wiring harness. If the harness is damaged in multiple places or has broken internal copper strands, replace the entire airbag wiring harness. After repair, re-secure the wiring harness and ensure sufficient clearance from the seat slide rails and metal brackets.
  • 8
    System verification: Restore all connections and reconnect the battery. Use the BYD VDS or a generic diagnostic tool to clear the fault code. Perform the SRS system self-check cycle. Confirm B163111 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Atto 3 (Yuan Plus) B-pillar wiring harness wear caused short circuit

✓
The airbag warning light on the instrument cluster was on constantly. VDS diagnosis showed DTC B163111. The technician disconnected the battery, removed the passenger-side B-pillar trim panel, and found that the wiring harness below the B-pillar interfered with the seat metal frame when the seat was moved to its rearmost position. Long-term friction had worn through the insulation of the yellow airbag wire, exposing the copper conductors and causing a short to ground against the vehicle body. The technician repaired the damaged wires with heat shrink tubing, rerouted the harness, and secured it with additional clips to maintain a clearance of more than 20 mm from the seat mechanism. Fault resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro seat connector oxidised due to water ingress

✓
Intermittent airbag light, sometimes with a warning chime. DTC B163111. Checked the airbag connector under the passenger seat and found water stains and green copper corrosion inside the plug, with terminals displaced. Traced the cause to liquid that got in during a previous deep interior clean, combined with an aged connector seal. Cleaned the connector terminals with electronic cleaner and fine sandpaper, applied conductive grease, replaced the seal, and secured the plug with a zip tie to prevent it from coming loose. The fault has not returned.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal fault in BYD Qin Pro passenger airbag module

✓
The airbag warning light stayed on continuously. The diagnostic tool showed code B163111. Initial inspection found no damage to the external wiring harness and the connectors looked normal. After disconnecting the airbag module, the harness-side insulation resistance to ground measured normal (greater than 10 MΩ). Measuring the module itself, however, showed near-zero resistance to ground on one terminal, indicating an internal squib short circuit. Replaced the genuine front passenger side airbag module (part number matched to the VIN), then coded and configured it using the diagnostic tool. Cleared the fault codes and the system passed the self-test. Fault resolved.
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]