AU
B162A1A

DTC B162A1A indicates the airbag control module (SRS ECU) detects a resistance of 0 ohms, or close to 0, in the driver's side airbag circuit (usually integrated into the seat side) — Seal U

Safety System

DTC B162A1A indicates the airbag control module (SRS ECU) detects a resistance of 0 ohms, or close to 0, in the driver's side airbag circuit (usually integrated into the seat side).

Normal airbag circuit resistance ranges from 2-3 ohms (including the airbag inflator resistance and wiring harness impedance).

A resistance of 0 indicates a short circuit.

Possible causes include damaged wiring harness insulation causing a short between positive and negative terminals, connector pins shorting to ground, an internal short in the airbag inflator, or an SRS control module sampling circuit fault.

This fault prevents the side airbag from deploying during a collision, resulting in a loss of protection.

In extreme cases, poor contact at the short circuit point can produce arcing and risk unintended deployment.

Triggering this fault code illuminates the instrument cluster airbag warning light and may disable the entire airbag system.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Seat slide rail or frame edge chafing the airbag wiring harness: Frequent driver seat adjustment rubs the yellow airbag wiring harness (located under the seat) against the metal slide rail. Prolonged friction damages the insulation, causing a core wire short to ground or a short between the positive and negative terminals.
  • 2Connector water ingress and oxidation: Vehicle wading, car washing, or sunroof leaks cause water ingress inside the under-seat airbag connector (typically located on the lower left side of the seat), resulting in a short circuit between pins or abnormally low resistance due to corrosion.
  • 3Improper seat removal or installation: After removing the seat during repair or modification, the airbag connector fails to seat fully (no audible click), the connector locking tab breaks, or metal debris enters the connector, short-circuiting the pins.
  • 4Wiring modification interference: When installing seat heating, ventilation, or massage functions, an improperly secured aftermarket wiring harness compresses and rubs against the factory airbag wiring harness, or pierces the insulation, causing a short circuit.
  • 5SRS control module fault: A fault in the internal sampling circuit, A/D converter, or a software calibration error causes the module to misread a normal resistance value as 0 ohms (confirm using an oscilloscope).
What To Do
  • 1
    Safety preparation: Switch the vehicle OFF, disconnect the low-voltage battery negative terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Visual inspection: Inspect the yellow dedicated wiring harness under the driver's seat (usually marked with yellow corrugated conduit or yellow tape) for wear, cuts, or crush marks. Focus on the seat slide rails, seat frame edges, and wiring harness bends.
  • 3
    Connector check: Inspect the airbag connector under the seat (usually yellow with a shorting bar) to confirm it is fully seated and the locking mechanism is intact. Check inside for water marks, oxidation, or foreign matter. If necessary, clean with electrical contact cleaner and blow dry.
  • 4
    Resistance measurement: Use a high-impedance digital multimeter (do not use an analog multimeter). Disconnect the airbag connector and measure the resistance on the wiring harness side (leading to the SRS ECU) and the airbag side (located inside the seat) separately. Normal airbag resistance is approximately 2-3 ohms. The wiring harness side must show an open circuit (infinite resistance). A reading of 0 ohms indicates a short circuit on the corresponding side.
  • 5
    Step-by-step inspection: If the short circuit is on the wiring harness side, unwrap and inspect the harness section by section along the circuit; if the short circuit is on the airbag side, remove the seat trim cover and inspect the side airbag inflator body (this usually requires replacing the seat airbag assembly).
  • 6
    Repair/Replace: Repair the damaged wiring harness (wrap with multiple layers of high-temperature insulating tape). Replace the damaged connector (use the genuine yellow dedicated airbag connector and engage the double lock). If the airbag inflator fails, replace the entire seat airbag module.
  • 7
    System verification: Reconnect all connectors and verify the shorting bar springs back normally. Reconnect the battery. Use VDS or a dedicated diagnostic tool to clear the fault code. Perform an SRS system self-check. Confirm B162A1A does not return and the instrument panel warning light turns off.
  • 8
    Function test: Move the seat forward and backward and adjust the backrest angle multiple times. Simulate driving vibration to confirm the fault no longer occurs intermittently.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Worn seat rails shorted the wiring harness on a BYD Qin Pro DM

✓
Symptoms: Airbag warning light stays on. VDS code: B162A1A. Diagnosis: Checked the wiring harness under the seat. The airbag wiring had rubbed against the seat rail over time, wearing through the insulation and causing a short circuit between the positive and negative wires. Resistance measured: 0.5 ohms. Resolution: Repaired the damaged wiring, rerouted and secured the harness away from the rail interference point, and cleaned the connector. Fault resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song MAX: Airbag connector water ingress after wading

✓
Symptoms: After washing the vehicle, the instrument cluster displayed 'Check Airbag System' and the warning light stayed on. Read DTC B162A1A. Diagnosis: Removed the driver seat and found water inside the side airbag connector. The pins had water stains and oxidation; resistance measured 0.2 ohms. Water entered through the seat rail gaps. Resolution: Dried the wiring harness, replaced the airbag connector, and installed waterproof plugs on the seat rails. Fault resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Yuan PLUS: Aftermarket heated seat installation caused poor connection

✓
Symptoms: Airbag warning light intermittently lit while driving. Historic DTC B162A1A stored; fault recurred when the seat was moved. Diagnosis: Checked the yellow connector under the seat. Found the locking tab broken and the wiring harness pinched during an aftermarket seat heater install, causing an intermittent short when the seat moved (resistance fluctuating between 0.3–2.1 ohms). Solution: Replaced the airbag wiring harness assembly and dedicated connector. Reorganized the aftermarket wiring. Fault completely resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM: Owner removed and refitted seats, connector not properly seated

✓
Symptoms: After the owner removed the seat for cleaning and started the vehicle, the airbag warning light stayed on constantly, and VDS reported DTC B162A1A. Diagnosis: Found the airbag connector not fully inserted (unlocked). Metal debris that fell inside during cleaning deformed the pins and caused a short circuit. Measured resistance: 0.8 ohms. A slightly deformed seat rail was compressing the wiring harness. Solution: Replaced the airbag connector, repaired the rail, ensured the connector locked into place, cleared the fault codes, and normal operation was restored.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Han EV airbag control module software fault

✓
Symptoms: At 3,000 km on a new vehicle, the airbag warning light illuminated. DTC B162A1A occurred intermittently. Wiring harness and airbag resistance measured normal (2.2 ohms). Diagnosis: Used an oscilloscope to monitor the SRS ECU and detected occasional abnormal fluctuations in the sampling voltage. Determined this to be an internal A/D conversion circuit or software calibration issue within the control module (batch quality defect). Solution: Upgraded the SRS control module software to V2.3.5. Fault persisted, so replaced the control module assembly under warranty. 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. Sources: [1]