AU
B1750

DTC B1750 indicates the SRS (Supplemental Restraint System) control unit detects an open circuit, abnormal resistance, or a physically missing Right Rear Side Airbag module — Seal U

Safety System

DTC B1750 indicates the SRS (Supplemental Restraint System) control unit detects an open circuit, abnormal resistance, or a physically missing Right Rear Side Airbag module.

This level 2 airbag system fault (a non-fatal hardware fault affecting passive safety functions) indicates the SRS control unit cannot establish normal communication with the right rear side airbag or detects infinite resistance in the airbag igniter circuit.

This fault prevents the right rear side airbag from deploying during a collision, severely compromising side-impact protection.

The instrument cluster continuously illuminates the airbag warning light.

Possible causes include an open circuit in the airbag module wiring harness, a loose connector, an open circuit in the internal airbag igniter, or incorrect airbag assembly installation following vehicle modification or repair.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Loose, oxidized, or poor contact at the right rear side airbag wiring harness connector (commonly the yellow connector inside the C-pillar trim panel or under the seat)
  • 2Airbag module internal igniter open circuit or resistance outside the standard range (normal: 1.8-2.5Ω; excessively high or low values trigger a fault).
  • 3Wiring harness wear or pinching at the door hinge, seat slide rail, or body panel hole causes an open circuit (especially on vehicles with frequent seat adjustment or door operation).
  • 4Short or open circuit in the communication wiring harness between the SRS control unit and the airbag module (typically containing two ignition loop wires and one diagnostic wire).
  • 5Failure to install a genuine airbag module after accident repairs, or installation of a mismatched or previously deployed used airbag assembly.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, and wait at least 3 minutes to fully discharge the SRS system capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use the BYD VDS2000 or VDS1000 diagnostic tool to read all fault codes. Confirm only B1750 or related sub-codes (such as B1750-00) are present, and record the freeze frame data.
  • 3
    Physical inspection: Remove the right rear C-pillar interior trim panel (or seat backrest, depending on airbag installation position). Check if the side airbag module is present and visually intact. Verify the yellow dedicated connector is fully seated and the locking tab is engaged.
  • 4
    Resistance measurement: Disconnect the airbag module connector. Use a multimeter to measure the resistance between the two terminals of the airbag squib. Standard value: 1.8-2.5Ω. If the reading is OL (open circuit) or >10Ω, replace the airbag module.
  • 5
    Harness continuity test: Measure harness continuity between the airbag connector and the SRS control unit (usually located under the centre console or in the front compartment). Inspect the harness sleeves at the door hinges and seat slide rails for damage, and check for backed-out pins.
  • 6
    Insulation check: Measure the insulation resistance of the airbag wiring harness to ground and to power. Resistance must be >10 MΩ to rule out a wiring harness short circuit.
  • 7
    Replacement verification: If the wiring harness is normal but resistance is abnormal, replace the OEM right rear side airbag module (part number must match vehicle model year) and reconnect the battery.
  • 8
    System reset: Clear the fault code, cycle the ignition switch three times, confirm the SRS system self-check passes, and verify the instrument warning light turns off. Use the diagnostic tool to read the data stream and confirm the airbag status displays 'Normal'.
Real-World Cases
BYD DTC AI Analysis

Oxidised right rear airbag connector caused DTC B1750 in BYD Song MAX

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Symptoms: Three years after purchase, the airbag warning light on the instrument cluster illuminated intermittently. It sometimes went off after restarting but eventually stayed on. Diagnosis: Used VDS2000 to retrieve DTC B1750 (right rear side airbag not present). Live data showed infinite resistance on this airbag circuit. Removed the right C-pillar trim and found white oxidation on the pins inside the yellow airbag harness connector. The connector locking tab was not fully engaged, likely caused by a previous audio system modification. Repair: Cleaned the connector pins with electronic contact cleaner, applied conductive grease, and reconnected the harness, making sure the locking tab engaged fully. Measured resistance recovered to 2.0Ω. Cleared the DTC and monitored the vehicle for one month. No recurrence.
BYD DTC AI Analysis

BYD Tang DM seat rail chafing wiring harness causing intermittent B1750

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Symptoms: While driving on rough roads, the airbag warning light occasionally flickered. The dealership inspected the vehicle multiple times without identifying the cause. Diagnostic Process: Retrieved intermittent fault code B1750. Inspected the airbag wiring harness beneath the right rear seat and found the harness had chafed at the seat rail mounting point, wearing through the insulation and partially fracturing the copper strands. Vibration caused momentary open circuits. Resolution: Repaired the harness by cutting out the damaged section, soldering the wires and insulating with heat-shrink tubing. Rerouted the wiring to clear the seat rail travel path and secured it with cable ties to the body wiring channel. Fault permanently resolved.
BYD DTC AI Analysis

Incorrect airbag module model after accident repair caused B1750 in BYD Yuan EV

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Symptoms: After a side impact, a non-authorised repairer replaced the right rear side airbag, but the instrument cluster kept displaying an airbag fault. Diagnosis: Retrieved DTC B1750. The new airbag's resistance measured normal, but VDS showed the airbag configuration code did not match the vehicle VIN. Inspection found the repairer had fitted an airbag module from a lower-spec variant (without side airbag) or used a previously deployed part. Repair: Ordered a genuine right rear side airbag module matching the vehicle specification (with correct resistance and recognition resistor). Installed it and performed SRS coding with VDS. Fault cleared.
BYD DTC AI Analysis

BYD Qin Pro SRS control unit software falsely reporting B1750

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Symptoms: The vehicle had no collision or modification history. The airbag warning light suddenly came on with DTC B1750. Diagnosis: Checked the wiring harness connectors – undamaged. Measured airbag resistance at 2.2Ω (normal). Wiggled the harness, but the fault did not reappear. Reviewed the BYD technical bulletin and found a software bug in the SRS control unit for this production batch that can falsely report an "airbag not present" fault during voltage fluctuations. Repair: Updated the SRS control unit software with VDS1000 from version V1.2 to V1.4. Cleared fault codes after the update. The fault has not returned.
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.