AU
B1768

DTC B1768 on models such as the 2019 BYD Song MAX and 2020 Qin ICE indicates a short to ground in the right front side curtain airbag ignition circuit — Seal U

Safety System

DTC B1768 on models such as the 2019 BYD Song MAX and 2020 Qin ICE indicates a short to ground in the right front side curtain airbag ignition circuit.

The SRS ECU detects abnormally low resistance in the airbag inflator circuit (usually <2Ω), indicating damaged wiring insulation causing a short to body ground, or an internal short circuit in the airbag module.

This fault prevents the affected airbag from deploying during a collision (fail-safe state) or, in very rare cases, creates a risk of unintended deployment due to circuit interference.

This constitutes a highest-level safety fault.

Note: Other BYD models (such as the Song Pro, Qin PLUS, and Han EV) may define B1768 as an abnormal left front door lock status signal.

Verify the specific vehicle model and year.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right front curtain airbag wiring harness chafed or crushed inside the A-pillar/B-pillar trim, shorting the wire to body metal.
  • 2Water ingress, oxidation, or bent pins at the airbag connector (usually located near the right roof grab handle or C-pillar), causing a short to ground.
  • 3Airbag module internal igniter resistance wire short circuit (internal fault); resistance measures close to 0 Ω.
  • 4After an accident, unrepaired metal burrs cut the airbag wiring harness, or the wiring harness was incorrectly wrapped during repairs.
  • 5SRS ECU internal monitoring circuit fault falsely reporting a short circuit (rare; confirm only after ruling out wiring faults).
What To Do
  • 1
    Safety preparation: Power off the vehicle and disconnect the negative battery terminal. Wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use VDS or a dedicated diagnostic tool to read the fault code, confirm B1768 is a current fault (Active), and record freeze frame data.
  • 3
    Visual inspection: Remove the right A-pillar, B-pillar, and headliner edge trim. Check the right front curtain airbag wiring harness (usually wrapped in yellow corrugated conduit) for obvious wear, cuts, or crush marks.
  • 4
    Connector inspection: Disconnect the connector between the airbag module and the main wiring harness (usually featuring a shorting bar). Check the pins for oxidation, water ingress, or deformation. Measure the resistance to ground on the harness side of the connector; the resistance must be infinite.
  • 5
    Resistance measurement: Use a multimeter to measure the igniter resistance on the airbag module side. The standard value is 2.0Ω-3.0Ω. A reading near 0Ω indicates an internal short circuit; replace the module.
  • 6
    Wiring repair: If the wiring harness is damaged, use dedicated heat-shrink tubing or replace the harness. Keep the harness clear of the vehicle body and secure it firmly to prevent further chafing.
  • 7
    System reset: After repair, reconnect all connectors, reinstall the trim panels, and connect the battery. Use the diagnostic tool to clear the fault code and perform an SRS system self-test. Confirm B1768 does not return and the airbag warning light turns off normally.
Real-World Cases
BYD DTC AI Analysis

Worn right A-pillar wiring harness caused B1768 in Song MAX

✓
Symptoms: Airbag warning light on. Scanner read B1768 (right front side curtain airbag short to ground). Diagnosis: Removed the A-pillar trim and found the right front airbag wiring harness chafing against the clip. Friction wore through the insulation, exposing the copper wire to the chassis metal. Repair: Repaired the damaged wiring, rerouted the harness to avoid the sharp clip, and replaced the airbag connector. Fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD Qin petrol version airbag connector water ingress, oxidation and short circuit

✓
Symptoms: Airbag warning light illuminated after driving in rain. DTC B1768. Diagnosis: Water entered the right front side airbag connector at the C-pillar due to a deteriorated rear window seal, causing pin oxidation and a short to ground. Repair: Cleaned and blow-dried the connector, applied dielectric grease, and replaced the rear window seal. Fault cleared.
Original source ↗
BYD DTC AI Analysis

After accident repair, unaddressed wiring harness burrs caused intermittent B1768

✓
Symptoms: Intermittent B1768 DTC after right front collision repairs. Diagnosis: The accident deformed the right side body structure. Metal burrs created during panel beating repairs pierced the SRS wiring loom insulation, causing intermittent shorts to ground over bumps. Repair: Ground down the burrs and replaced the damaged loom section. Fault fully resolved.
Original source ↗
BYD DTC AI Analysis

Internal short circuit in right front side curtain airbag module

✓
Symptom: Airbag warning light stays on; DTC B1768 cannot clear. Diagnosis: Disconnected the airbag module connector and measured 0.3Ω at the module side (normal: 2–3Ω). Determined internal short in the airbag igniter. Repair: Replaced the right front side curtain airbag module, reconfigured the SRS system, and cleared the fault code.
Original source ↗
BYD DTC AI Analysis

Loose connection at SRS ECU connector causing false B1768

✓
Symptoms: Airbag warning light illuminates intermittently when driving on bumpy roads, storing DTC B1768. Diagnosis: Inspected wiring—no damage found. Resistance measurements normal. SRS ECU connector pin partially backed out, causing abnormal monitoring voltage and false short-circuit detection. Repair: Reseated ECU connector pin and secured connection. Fault resolved.
Original source ↗
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.