AU
B160212

DTC B160212 indicates the SRS (Supplemental Restraint System) control unit detects an abnormal short circuit between the driver’s front airbag inflator circuit and the vehicle power supply (12V+B) — Seal U

Safety System

DTC B160212 indicates the SRS (Supplemental Restraint System) control unit detects an abnormal short circuit between the driver’s front airbag inflator circuit and the vehicle power supply (12V+B).

The inflator circuit normally maintains a high-resistance state (typically 2-3Ω, determined by the inflator internal resistance).

The control unit continuously monitors circuit voltage and resistance via an internal bridge detection circuit.

A short circuit to power indicates the voltage at one or both ends of the circuit continuously exceeds the threshold (typically above 5V) and the resistance is abnormally low.

This fault triggers the safety protection mechanism.

The system immediately enters fail-safe mode and disables the airbag deployment function to prevent accidental deployment caused by short-circuit current.

Hardware faults such as an internal clock spring short circuit, damaged wiring harness insulation contacting a power wire, or a driver transistor breakdown inside the SRS ECU may accompany this fault.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Broken internal conductor or aged insulation in the clock spring (spiral cable/clockspring reel) shorts the airbag circuit to the horn power wire or steering wheel heating power wire.
  • 2Long-term steering friction damages the driver's airbag wiring harness insulation at the steering column sleeve, causing contact with the ignition switch power wire or constant power circuit.
  • 3Incorrect wiring during aftermarket steering wheel modifications (such as adding multi-function buttons or a steering wheel heating module) mistakenly connects the 12V power supply to the airbag circuit.
  • 4Internal boost capacitor or drive circuit fault in the SRS control unit, causing the detection terminal to continuously output a high level.
  • 5Liquid enters the connector below the steering wheel during interior cleaning or driving through water, causing an electrolytic corrosion short circuit between the airbag circuit terminal and the power supply terminal.
What To Do
  • 1
    Use the BYD dedicated diagnostic tool VDS2000/VDS1000 to read the complete fault codes and freeze frame data. Confirm whether B160212 is an active or history fault. Record parameters such as vehicle speed and time when the fault occurred.
  • 2
    Perform the standard safe power-down procedure: disconnect the low-voltage battery negative terminal and wait at least 90 seconds (to ensure the SRS backup capacitor fully discharges). Do not operate any electrical equipment during this time.
  • 3
    Remove the service covers on both sides of the steering wheel. Use a shorting plug or insulated tool to disconnect the main airbag module connector (usually located at the upper end of the clock spring). Inspect the connector terminals (usually yellow) for signs of burning, backed-out pins, or water ingress corrosion.
  • 4
    Use a high-impedance digital multimeter (≥10MΩ) to measure the airbag circuit voltage to power supply: connect the negative probe to body ground and probe the two airbag circuit terminals separately with the positive probe. The normal reading is <1V; if the multimeter reads 12V battery voltage, this confirms a short to power supply.
  • 5
    Segmented isolation diagnosis: Disconnect the connector between the body wiring harness and the lower end of the clock spring. Measure the resistance/voltage to power on the airbag module side (upper end of the clock spring) and the body wiring harness side to determine whether the short circuit is in the clock spring/airbag module section or the body wiring harness/SRS ECU section.
  • 6
    Check the clock spring: Measure continuity between corresponding pins at the upper and lower ends. Normal resistance must be <3Ω. Turn the steering wheel from lock to lock. Resistance must remain stable without sudden changes. Measure insulation resistance between each pin and the housing. Resistance must be >10MΩ.
  • 7
    Check the steering column wiring harness: Remove the lower trim panel and carefully inspect inside the harness corrugated conduit for cuts from the steering column metal edge, or tangling and contact with the ignition switch power wire (usually red or pink).
  • 8
    If the wiring harness and clock spring are normal, check the SRS ECU: measure the corresponding pins on the ECU harness connector (usually the airbag deployment pins in the 18-pin or 24-pin connector) for abnormal voltage output under static conditions. If necessary, use an oscilloscope to check the deployment waveform.
  • 9
    Repair the damaged wiring harness (insulate with heat-shrink tubing) or replace the faulty component (clock spring, SRS ECU, or airbag module). Never simply wrap the harness with tape.
  • 10
    Reconnect all connections and turn on the power. Use VDS to clear the fault code. Perform the SRS system self-check (System Check). Confirm the B160212 status changes to 'Passed' and the instrument panel airbag warning lamp turns off normally after the self-check.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short circuit in the clock spring caused DTC B160212 on the Qin Pro DM

✓
A 2019 Qin Pro DM with 30,000 km displayed "Check SRS System" on the instrument panel. The scan tool retrieved active fault code B160212. Disassembly found the clock spring's internal flat cable had insulation damage at the third turn, contacting the adjacent horn power wire (12V constant) and creating a short circuit. Replacing the clock spring with a genuine unit (P/N BYD-EG-5820100) cleared the fault. The cause: prolonged full-lock steering led to cable overstretching and fatigue.
BYD DTC AI AnalysisFrom Chinese market (translated)

E2 aftermarket steering wheel heater caused airbag power supply short circuit

✓
A 2020 BYD E2 owner fitted an aftermarket steering wheel heating cover and incorrectly connected the heating power wire to unused terminals on the airbag connector (on some models spare terminals sit adjacent to the airbag circuit). While driving, vibration caused the terminals to make contact, triggering DTC B160212. During repair, technicians found burned airbag harness terminals. Replaced the clock spring and airbag harness connector, removed the unauthorised modification wiring, and resolved the fault. Never modify SRS-related circuits.
BYD DTC AI AnalysisFrom Chinese market (translated)

Flood-damaged vehicle SRS connector corroded and shorted

✓
The 2019 Qin EV had a blocked sunroof drain tube that caused rainwater to accumulate beneath the A-pillar and leak into the wiring harness connector below the steering wheel. Disassembly revealed electrolytic corrosion deposits between the airbag circuit terminal and the power terminal inside the connector, forming a low-resistance path (measured at approximately 200 ohms). Cleaning the connector terminals, treating them with an electronic cleaner, applying conductive protective grease, and repairing the wiring harness insulation cleared the fault. Clearing the drain tube prevented further water ingress.
BYD DTC AI AnalysisFrom Chinese market (translated)

False positive: SRS ECU internal driver circuit fault

✓
An E3 vehicle repeatedly logged DTC B160212. Replacing the clock spring and airbag module did not fix the fault. Oscilloscope testing found an abnormal 12V on the SRS ECU airbag drive terminal at rest (normally 0V or a pulse detection voltage). Disassembling the ECU revealed a shorted diode next to the internal boost capacitor, causing the detection circuit to incorrectly interpret a short to power. Replacing the SRS control unit (online programming and matching required) completely resolved the fault.
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]