AU
B160A1A

DTC B160A1A indicates abnormally high resistance (open circuit or high-resistance condition) in the driver-side front airbag (stage 1) ignition circuit — Seal U

Safety System

DTC B160A1A indicates abnormally high resistance (open circuit or high-resistance condition) in the driver-side front airbag (stage 1) ignition circuit.

This is a critical Supplemental Restraint System (SRS) safety fault.

Normal airbag igniter resistance is 1.5-3.5Ω.

If the system detects resistance continuously exceeding the threshold (typically >5Ω or open circuit), it identifies an ignition circuit integrity fault.

The SRS control unit then illuminates the instrument cluster airbag warning light and enters fail-safe mode.

This condition may prevent the driver-side airbag from deploying during a collision.

The fault indicates an electrical connection issue in the circuit, not an explosion risk from the airbag itself.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1The flat cable inside the clock spring is broken, has fatigue damage, or has poor contact. An internal open circuit easily occurs, especially after frequently turning the steering wheel to full lock or prolonged left-to-right rotation.
  • 2The yellow airbag wiring harness connector beneath the steering wheel (usually with a double-locking mechanism) is not fully seated, or the pins are backed out, oxidized, corroded, or have excessive contact resistance.
  • 3Driver airbag module internal igniter resistance abnormally high or open circuit, or module itself damaged (rare but possible).
  • 4Airbag wiring harness cut, damage, loose connection, insulation damage, or waterproof seal failure caused during accident repair or steering wheel modification.
  • 5Very rare causes include an internal fault in the SRS control unit sampling circuit, a software version defect, or a poor ground.
What To Do
  • 1
    Safety Preparation: Disconnect the negative battery cable and wait at least 3 minutes to discharge residual capacitor charge and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation: Use the BYD dedicated diagnostic tool to read the SRS system fault codes. Confirm B160A1A is a current fault (Active) and cannot be cleared. Record the freeze frame data.
  • 3
    Initial inspection: Check if the yellow airbag connector under the steering wheel (spiral cable to body wiring harness connection) is fully seated, if the locking tab is broken, and if the wiring harness has obvious damage or crush marks.
  • 4
    Clock spring inspection: Remove the steering wheel and disconnect the airbag module connector. Measure the resistance between the terminals on both sides of the clock spring using a multimeter. Standard resistance: <1Ω. Slowly turn the steering wheel lock-to-lock and verify the resistance remains stable without fluctuation.
  • 5
    Circuit continuity check: If the clock spring is normal, measure the continuity and insulation of the wiring harness from the clock spring to the SRS control unit. Specifically check the wiring harness for wear where it passes through the steering column area.
  • 6
    Airbag module inspection: If the circuit is normal, use a dedicated shorting lead or multimeter to directly measure the resistance between the two terminals of the airbag module igniter. Normal range: 1.5-3.5Ω. If the resistance is too high, replace the module.
  • 7
    Repair/Replace: Based on measurement results, replace with an OEM clock spring (70% probability), repair poor wiring harness connections (20% probability), or replace the airbag module (10% probability). Never use aftermarket resistor bypass modules.
  • 8
    System reset verification: Reconnect all connectors and the battery, clear the fault code, and perform the SRS system self-check cycle (cycle the ignition ON-OFF three times or perform a driving self-check). Confirm the warning light turns off and the fault code does not return.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin Pro DM clock spring internal open circuit

✓
Symptoms: The airbag warning light stayed on suddenly during normal driving. Previously, the steering wheel made abnormal noise at full lock. Diagnosis: A diagnostic tool read DTC B160A1A. Removed and inspected the clock spring, revealing wear at the base. Static resistance measured 3.5Ω by multimeter (abnormal). Resistance intermittently went to infinite (open circuit) when turning the steering wheel. Confirmed the internal ribbon cable was broken. Resolution: Replaced the OEM clock spring assembly, cleared the fault codes, and the system returned to normal. Cost: about 300–600 yuan.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro: Airbag connector loose, poor contact

✓
Symptoms: Airbag warning light stays on after accident repair. DTCs reappear after clearing. Diagnosis: Yellow airbag connector under steering wheel not fully seated. Terminal retraction caused contact resistance 5.8 Ω (excessive). Resolution: Repaired terminal using extraction tool. Reconnected and confirmed locking click. Secured wiring loom with cable ties to prevent loosening. Cleared DTCs; fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD e5 commercial vehicle: clock spring ribbon cable fatigue wear

✓
Symptoms: 180,000 km rideshare vehicle. Airbag warning light flashes intermittently then stays on, worse in damp weather. Diagnosis: Prolonged full-lock steering caused the clock spring to exceed its fatigue life. Resistance unstable (fluctuating 1.2–6.8 Ω), jumping when the housing was tapped. Fix: Replaced with a compatible clock spring, greased rotating parts, advised avoiding prolonged full-lock steering. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM airbag module internal fault

✓
Symptoms: Airbag warning light on with no accident history. Fault returned one month after clock spring replacement. Diagnosis: Confirmed the replacement clock spring was normal (0.8Ω). Disconnected the connector and installed a 2.5Ω dummy resistor at the circuit end; the fault could be cleared, indicating a module issue. Removed and tested the airbag igniter — measured 8.2Ω resistance, severely out of specification. Resolution: Replaced the driver-side airbag module and checked the SRS control unit version at the same time. Fault fully resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Steering wheel modification on a BYD Yuan EV damaged the wiring harness.

✓
Symptoms: After reverting from an aftermarket racing steering wheel to the factory unit, the airbag warning light stayed on with DTC B160A1A. A previous attempt to bypass with a resistor had no effect. Diagnosis: Found the wiring harness between the clock spring and airbag module cut and joined with electrical tape. Temperature changes and vibration loosened the tape, causing copper oxidation and a contact resistance of 4.2Ω. Insulation damage was also present. Resolution: Removed the splice point and repaired using a sealed waterproof connector or a soldered splice with heat-shrink tubing, achieving a stable resistance of 2.0Ω. Recommend avoiding modifications that damage the factory wiring harness.
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]