AU
B1760

DTC B1760 indicates the SRS (Supplemental Restraint System) control unit detects the Left Front Side Curtain Airbag in a "not present" state — Seal U

Safety System

DTC B1760 indicates the SRS (Supplemental Restraint System) control unit detects the Left Front Side Curtain Airbag in a "not present" state.

This means the ECU cannot identify the airbag electrical circuit during the self-check, or detects an open circuit or abnormal resistance (normal resistance is approximately 2-5Ω).

The side curtain airbag (CAB) mounts inside the roof side rail and protects occupant heads during a side impact or rollover.

This level 2 safety system fault prevents the left front side curtain airbag from deploying during a collision and continuously illuminates the instrument cluster airbag warning light.

On certain BYD models (such as the Song MAX and Qin petrol version), this fault code may also indicate a driver seat position sensor circuit fault.

The SRS uses seat position data to determine the airbag deployment strategy; a failed sensor can cause the system to log a similar code.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Left front curtain airbag wiring harness open or short circuit (commonly at A-pillar or B-pillar harness connection points, or chafing of the harness passing under the seat)
  • 2Loose airbag connector, backed-out terminals, oxidation, or water ingress (especially adapter connectors below the A-pillar, inside the headliner, or under the seat)
  • 3Open circuit or abnormal resistance in the airbag module internal squib circuit (normal resistance: 2-5 Ω; values outside this range register as not present).
  • 4Internal SRS ECU fault or software version defect causing false detection
  • 5Vehicle wading, oxidized wiring harness connectors due to water ingress after wading, or failure to correctly reconnect the wiring harness after modifying seats or removing the headliner.
What To Do
  • 1
    Use the BYD VDS or Launch X-431 diagnostic tool to read freeze frame data and confirm vehicle status, ambient temperature, and voltage conditions at the time of the fault.
  • 2
    Turn off the ignition, disconnect the negative battery terminal, and wait at least 90 seconds to completely discharge the SRS system and prevent accidental airbag deployment.
  • 3
    Visually inspect the left front side curtain airbag connector (located below the A-pillar, inside the headlining trim panel, or under the seat) for looseness, corrosion, backed-out terminals, or water ingress.
  • 4
    Use a multimeter to measure the airbag circuit resistance: Disconnect the SRS ECU connector. Measure the resistance from the wiring harness side to the airbag. The resistance must be between 2-5 Ω. (Measure using an adapter plug. Do not measure the airbag connector directly to prevent static electricity from deploying the airbag.)
  • 5
    Check wiring harness continuity: Measure the wiring harness between the SRS ECU and the left front side curtain airbag. Verify no open circuits, short circuits, or shorts to ground.
  • 6
    If the wiring harness resistance is normal, check the seat position sensor (if applicable): measure the 5V sensor supply, verify the signal voltage varies between 0.5-4.5V with position, and check for a normal ground.
  • 7
    If the wiring harness is normal, perform a substitution test using a known-good airbag module or sensor (Caution: disconnect power before proceeding).
  • 8
    Check the SRS ECU power supply (constant +B), ground, and CAN communication line voltage.
  • 9
    After repair, reconnect the battery, clear the fault code, perform an SRS system self-check (turn the ignition switch to ON and verify the indicator light turns off), and perform a road test to verify.
Real-World Cases
BYD DTC AI Analysis

BYD Song Pro - Seat rail chafes wiring harness causing B1760 false positive

✓
Airbag warning light remained on after startup. Scan tool retrieved DTC B1760. In the Song Pro, this code actually points to a driver seat position sensor circuit fault. Removing the driver's seat revealed the seat rails had worn through the position sensor wiring harness during fore-aft adjustment. Two of the three internal wires were completely fractured, creating an open circuit that the SRS system reported as "not present". Repaired the broken harness, rerouted it to the outside of the rails and reinforced it with corrugated tubing. Cleared the codes; system returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Qin Plus DM-i - Sensor connector poor contact

✓
While driving, the dashboard intermittently displayed "Check SRS System". The fault occurred more frequently in rainy or humid weather. The diagnostic scanner detected an intermittent B1760 code. Inspection of the position sensor connector beneath the driver's seat revealed a loose locking tab and internal oxidation. Resistance fluctuated severely when gently shaking the wiring harness. Cleaned the pins with electronic contact cleaner, adjusted the connector locking tab spring, applied conductive grease to enhance waterproofing, and secured the wiring harness with cable ties to eliminate vibration. One month of post-repair monitoring confirmed no recurrence.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM - Seat position sensor unit damaged

✓
Seat memory failed to store positions; the instrument cluster displayed B1760. Autel MS906S live data showed the driver seat fore-aft position signal stuck at 255 (invalid data), unchanged during seat movement. Sensor 5V supply was normal. Fault traced to worn internal sliding resistor film. Replaced the driver seat position sensor assembly (BYD-69F-001), performed sensor zero-point calibration with the special tool, and reset the memory positions. Seat welcome and memory functions returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Han EV - Factory Assembly Defect on New Car

✓
At 800 km, the airbag warning light suddenly illuminated. The dealership diagnostic tool showed B1760. Inspected the driver seat position sensor and found the fixing clip was not fully engaged (factory assembly defect). A 2–3 mm gap between the sensor and seat rail caused the position detection signal to drift, and the SRS system determined the sensor was "not present". Reinstalled the sensor ensuring the clip fully engaged, added a 1 mm rubber shim to eliminate the gap and dampen vibration, and performed calibration using the diagnostic tool. Repaired free of charge under warranty.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX - Multi-system faults following water ingress

✓
After driving through water, the dashboard simultaneously displayed faults for the airbag, ESP, and tire pressure monitoring systems. The scan tool retrieved multiple DTCs including B1760 and C0035. Inspection under the seat found approximately 5ml of standing water and sediment inside the wiring harness connector; the seat position sensor was shorted to ground. Determined that water ingress caused sensor damage and connector corrosion. Replaced the driver's seat position sensor and the corroded wiring harness connector, thoroughly cleaned and blow-dried the harness, applied waterproof silicone grease to critical connectors, cleared the fault codes, and all systems returned to normal.
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.