AU
B1632-00

B1632-00 indicates a short circuit to vehicle power (B+) in the front passenger (right) side airbag ignition circuit — Seal U

Safety System

B1632-00 indicates a short circuit to vehicle power (B+) in the front passenger (right) side airbag ignition circuit.

In the BYD SRS (Supplemental Restraint System) architecture, this fault specifically refers to abnormal continuity between the inflator circuit of the front passenger seat side airbag or the right curtain airbag and 12V constant power or ignition power.

This fault is a hard short.

The SRS control unit (ACU) detects the ignition circuit voltage continuously exceeding the threshold (typically >5V).

To prevent unexpected deployment, the system immediately cuts off the affected airbag ignition circuit and illuminates the airbag fault warning lamp (SRS MIL).

This fault presents an extremely high safety risk: the short circuit may cause unexpected airbag deployment resulting in personal injury.

Additionally, the fault prevents normal airbag deployment, disabling collision protection.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Worn wiring harness under the front passenger seat: Frequent fore-aft seat adjustment causes the side airbag wiring harness (usually integrated into the seat wiring harness) to rub against the seat track and slide rail bracket. Damaged insulation allows the wires to contact live parts of the metal frame.
  • 2Right front door hinge wiring harness crushed: The curtain airbag is located above the door or in the B-pillar. Frequent opening and closing of the door crushes and chafes the door-to-body wiring harness, causing power wires (such as door lock or window regulator power supplies) to short circuit with the airbag igniter wire.
  • 3Airbag igniter internal short circuit: The front passenger-side airbag module internal igniter resistance wire shorts to the housing or power terminal. Manufacturing defects, airbag aging, or previous physical impact typically cause this.
  • 4Water ingress or liquid contamination: Water entering the front passenger seat or carpet (A/C condensate, sunroof leaks, spilled drinks) causes a short circuit or conductive corrosion between the airbag connector terminals (usually located under the seat or at the base of the B-pillar).
  • 5Improper modification or repair: fixing nails piercing the wiring harness during installation of seat covers, seat heating pads, or floor sound insulation; or improper wiring harness routing after collision repairs, causing seat tracks or door panel clips to pinch the harness and damage the insulation.
What To Do
  • 1
    Safety isolation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS energy storage capacitor. Hang an 'Airbag Under Repair' warning sign. Do not switch on the power during the repair.
  • 2
    Fault confirmation and freeze frame analysis: Connect the VDS2000 or Launch X431 diagnostic tool. Read the freeze frame data for DTC B1632-00. Confirm the vehicle speed, temperature, and voltage conditions when the fault occurred to determine if it is an intermittent fault.
  • 3
    Visual and physical inspection: Check the front passenger seat, right front door trim panel, and B-pillar trim panel for signs of removal. Check the wiring harness under the seat, at the door hinge, and at floor harness pass-through points for abrasion, crushing, water ingress, or burn marks. Focus on the dedicated yellow SRS wiring harness (usually double-insulated).
  • 4
    Circuit isolation test: Remove the SRS control unit (ACU), disconnect the front passenger airbag connector (usually located on the floor harness or under the seat), and use a multimeter to test the airbag-side harness for a short to power: measure the resistance between the ignition wire (usually yellow/black) and B+; normal resistance is infinite. Measure the igniter resistance (through the airbag connector); normal resistance is 2.0-3.0 Ω.
  • 5
    Harness continuity and insulation test: If the harness shorts, use a probe to measure continuity section by section from the ACU connector to the airbag connector. Focus on the area beneath the seat track and the door hinge bend. If damaged, repair the wire with solder, double-insulate with heat-shrink tubing, install abrasion-resistant corrugated conduit and fleece tape, and adjust the harness routing to prevent interference with moving parts.
  • 6
    Airbag module inspection: If the wiring harness is normal, directly measure the resistance between the airbag module igniter terminals and the insulation to the housing. If an internal short circuit exists, replace the front passenger airbag assembly (never repair the airbag module). Record the serial numbers of the old and new modules during replacement.
  • 7
    SRS system reset: After repair, reconnect all connectors (listen for the locking click), connect the battery, and clear the fault code. Use the diagnostic tool to perform the 'SRS Configuration' or 'Coding' function (some models require reconfiguring airbag parameters after replacing components), then perform 'System Self-learning'.
  • 8
    Function verification: Perform a static test: read the data stream to confirm the front passenger airbag resistance is within the normal range (2.3 ± 0.3 Ω) and the voltage is 0 V; perform a dynamic simulation (use an airbag test tool to simulate the load; do not directly measure the igniter) and confirm the system generates no fault codes.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV450 passenger seat wiring harness chafing caused airbag short circuit

✓
Symptoms: The SRS light on the dash stayed on. Pulled fault code B1632-00 (passenger side airbag short to power). Freeze frame data showed the fault triggered after adjusting the seat. Diagnosis: Removed the passenger seat. The under-seat wiring harness had worn through on the sharp edge of the slide rail when the seat was at its front-most position. The yellow airbag wire (IGN+) and the seat heating power wire (12V constant) were making contact with their conductors exposed. Measured 12V on the airbag wire to ground. Fix: Repaired the damaged harness – cut out the damaged section, soldered in an extension, and insulated with heat shrink tubing. Installed a rubber grommet along the rail edge. Adjusted the harness attachment point to add slack. Cleared the fault code; airbag circuit resistance returned to 2.4 Ω.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro DM right front door hinge wiring harness pinched short

✓
Symptoms: Following an accident repair (RH front door replacement), the instrument cluster displayed an airbag fault. The diagnostic scanner reported DTC B1632-00. Diagnosis: Inspection of the wiring harness at the door hinge revealed the previous repair had not secured it correctly. The hinge was pinching the harness when closing the door, damaging the insulation of the curtain airbag igniter wire (yellow/green) and door lock power wire (red/white) and causing a short circuit. Solution: Replaced the RH front door wiring harness assembly (the damage was too concentrated to repair). Re-routed the harness according to the standard layout and secured it using the dedicated retaining clips, ensuring the wiring does not interfere with the hinge in either the fully open or fully closed position. Fault rectified.
BYD DTC AI AnalysisFrom Chinese market (translated)

Front passenger airbag connector corroded and shorted after the Qin 100 waded through water.

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Symptoms: After a heavy rainstorm, the vehicle drove through floodwater (water submerged the floor), the SRS warning light came on and DTC B1632-00 was stored. Diagnosis: Found water pooling under the front passenger seat. The SRS wiring harness connector (2-pin yellow plug) had internal water ingress, with copper oxide buildup between terminals causing a short circuit between positive and negative (measured resistance: 0.8Ω). Resolution: Completely removed the standing water, cleaned the connector terminals with electronic contact cleaner, blow-dried them, and applied conductive protectant. Replaced the airbag harness connector due to severe corrosion, then re-waterproofed the connection by wrapping with waterproof tape and fitting a waterproof boot. Cleared the fault code.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV300 Airbag Module Internal Fault Replacement Case

✓
Symptoms: No collision history. SRS warning lamp illuminated suddenly while driving. DTC B1632-00 could not be cleared. Diagnosis: Disconnected the passenger-side airbag connector. Measured harness side for short to power — none found. Measured directly at the airbag module igniter terminals and found continuity to the airbag housing (short to ground), confirming internal insulation failure of the igniter. Solution: Replaced the passenger seat side airbag assembly (part no. ...). Used new fixing bolts tightened to standard torque (typically 8–10 Nm). Ensured correct airbag orientation (label facing outward). Performed new module configuration via diagnostic tool. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Modified seat covers on a Qin 80 pierced the wiring harness, causing a short circuit.

✓
Symptoms: One week after fitting leather seat covers, the dashboard displayed an airbag fault warning. Read DTC B1632-00. Diagnosis: Inspected the passenger seat and found the metal retaining clips used to secure the seat covers were too long. They had pierced the seat side and penetrated the SRS wiring harness, puncturing the airbag igniter wire. The damaged wire contacted both the metal clip (body earth) and adjacent power supply wires simultaneously, creating a short to power. Resolution: Removed the non-compliant modification clips. Repaired the damaged wiring (as the damage was scattered, replaced the entire seat harness after local repairs). Refitted the seat covers with dedicated plastic clips, keeping them clear of the airbag harness routing. Cleared the fault codes.
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]