AU
B1630

DTC B1630 indicates the SRS (Supplemental Restraint System) detected an open circuit or abnormally high resistance in the front passenger seat side airbag circuit — Seal U

Safety System

DTC B1630 indicates the SRS (Supplemental Restraint System) detected an open circuit or abnormally high resistance in the front passenger seat side airbag circuit.

The ECU determines the airbag module is incorrectly connected.

Potential fault locations include the front passenger seat side airbag assembly, connecting wiring, under-seat wiring harness connector, or the airbag control unit (ACU) internal driver circuit.

During system self-check, the ACU confirms the connection status by monitoring the airbag squib circuit resistance.

Normal resistance typically ranges from 2.0-3.0 ohms (depending on the vehicle model).

If the ACU detects an open circuit (infinite resistance) or resistance exceeding the threshold, it triggers this fault code.

This fault prevents the front passenger side airbag from deploying during a side-impact collision.

The system also illuminates the instrument cluster airbag warning light and may disable the entire SRS, significantly reducing vehicle passive safety.

Note: Some vehicle models or documentation define B1630 as a seat belt pretensioner circuit fault.

Consult the specific vehicle service manual during repair.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Front passenger seat side airbag connector loose or disconnected (typically caused by an improperly seated yellow wiring harness plug under the seat, a damaged retaining clip, or failing to reconnect the harness after seat removal and installation)
  • 2Frequent seat adjustment causes fatigue fracture in the airbag wiring harness (especially the harness section between the seat rail and B-pillar, where repeated bending causes internal breakage or wear).
  • 3Front passenger side airbag module internal squib open circuit (internal open circuit due to airbag assembly internal fault or end of service life)
  • 4Wiring harness moisture and corrosion (water ingress, improper seat cleaning, or poor sealing causing connector pin oxidation and increased contact resistance)
  • 5SRS control module (ACU) internal driver circuit fault (ECU internal monitoring circuit false alarm or damaged driver chip)
What To Do
  • 1
    Safe power down: Turn off the ignition switch, disconnect the battery negative terminal, and wait at least 3 minutes (5 minutes for some models) to fully discharge the SRS capacitor and prevent accidental airbag deployment during repair.
  • 2
    Visual inspection: Remove the front passenger seat side trim panel and the protective cover beneath the seat. Verify the airbag wiring harness connector (usually a yellow plug) seats fully and the locking tab engages securely. Inspect the plug for water ingress, corrosion, or recessed pins.
  • 3
    Resistance measurement: Disconnect the airbag control module connector. Use a multimeter to measure the front passenger side airbag circuit resistance (measure resistance between the corresponding pins on the ACU harness side). Normal resistance is 2-5 ohms. Infinite resistance indicates an open circuit; 0 ohms indicates a short circuit.
  • 4
    Circuit continuity test: Check circuit continuity between the under-seat wiring harness and the ACU. Inspect the wiring harness near the seat adjustment mechanism and inside the B-pillar trim panel for wear, crushing, or breaks. Measure circuit insulation resistance to ground and power.
  • 5
    Component replacement verification: If circuit continuity is normal but resistance is abnormal, replace the front passenger side airbag module. If confirming an ACU drive circuit fault (measuring no normal detection voltage at the ACU output terminal), replace the airbag control module.
  • 6
    System reset and calibration: Reconnect the battery. Use the BYD VDS or a dedicated diagnostic tool to clear the fault codes. Perform the SRS system self-check and configuration calibration (some models require writing the vehicle VIN and configuration code after replacing the ACU). Confirm the fault code does not return and the warning light turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Surui seat belt pretensioner circuit intermittent fault

✓
Symptoms: The dashboard airbag warning light was constantly on. A diagnostic scan revealed fault code B1630. Some owners reported that the warning light suddenly came on while driving without any obvious collision or impact. Diagnosis: Connected a dedicated diagnostic scanner to the vehicle's OBD port and retrieved fault code B1630. Based on the code definition, this indicated an airbag system fault (some sources define this as a driver's side seatbelt pretensioner or airbag sensor circuit issue). Inspected the driver's side seatbelt pretensioner connector and found the plug loose. Measured the relevant circuit resistance and found an intermittent open circuit in the wiring. Resolution: Disconnected and reconnected the driver's side seatbelt pretensioner connector and secured it. Cleaned and reinforced the wiring. Cleared the fault codes with the diagnostic scanner and conducted a road test to confirm the fault was resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song MAX airbag wiring harness chafing fault

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Symptoms: The airbag warning light on the dashboard stays on continuously after starting the vehicle, with intermittent flashing. The vehicle has no collision history, but the warning light keeps recurring. Diagnosis: Scanned the system using VDS and retrieved DTC B1630. Checked the airbag control module power supply and earth circuits and found no abnormalities. Inspected the airbag sensor and wiring harness around the B-pillar. Found chafing on the wiring harness inside the left B-pillar trim, with some conductors exposed. Resolution: Repaired the damaged wiring harness and wrapped it with insulation tape. Rerouted and secured the harness to prevent chafing against metal edges. Replaced the damaged airbag sensor where necessary. Cleared the fault code and performed multiple start-up tests to confirm normal operation.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Poor contact at seatbelt pretensioner connector on BYD Qin

✓
Symptom: Airbag warning light illuminated while driving. DTC B1630 stored. Owner reported recent seat removal and refitting work. Diagnostic process: Retrieved DTC B1630: seat belt pretensioner circuit short to ground. Inspected driver and passenger side seat belt pretensioner connectors. Found driver side seat belt pretensioner harness connector beneath the seat not fully inserted. Measured pretensioner resistance, confirming intermittent fault caused by poor connector contact. Solution: Reconnected seat belt pretensioner connector correctly. Secured wiring harness with cable ties to prevent loosening during driving. Cleared DTC and conducted road test; fault did not return.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro collision sensor communication fault

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Symptoms: Vehicle had no accident history. Dashboard displayed airbag system fault warning. DTC B1630 retrieved. Vehicle intermittently exhibited no-start and hard starting conditions. Diagnosis: Performed deep scan with diagnostic tool. Found communication fault between airbag control module and vehicle controller. Inspected CAN network wiring and measured termination resistance and voltage. Found loose ground wire bolt on airbag control module. Tightening the bolt restored normal communication, but DTC B1630 remained. Further inspection found internal fault in left collision sensor. Resolution: Tightened airbag control module ground wire bolt. Replaced left collision sensor. Recalibrated airbag system. Cleared fault codes and performed comprehensive test.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Surui airbag control module internal fault

✓
Symptoms: After being parked overnight, the airbag warning light stayed on at startup. DTC B1630 retrieved. No collision or water ingress history. Diagnostic Procedure: Retrieved DTC B1630 with a scan tool; the code would not clear. Checked airbag control module power, ground and CAN wiring – all normal. Inspected airbag sensors and seatbelt pretensioners; found no wiring shorts or opens. Checked airbag control module communication waveforms with an oscilloscope; readings were abnormal. Determined the airbag control module had an internal fault. Resolution: Replaced the airbag control module (immobiliser matching and system calibration required). Rewrote vehicle configuration data. Cleared DTCs and performed comprehensive system tests.
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]