AU
B160C

DTC B160C indicates the SRS (Supplemental Restraint System) control unit detects the driver-side front airbag (steering wheel main airbag) ignition circuit resistance exceeds the normal upper limit (normal range: 2 — Seal U

Safety System

DTC B160C indicates the SRS (Supplemental Restraint System) control unit detects the driver-side front airbag (steering wheel main airbag) ignition circuit resistance exceeds the normal upper limit (normal range: 2.0–3.0 Ω; fault threshold: ≥4.0 Ω or open circuit).

This hard or intermittent fault indicates a high-resistance condition in the airbag ignition circuit.

Poor contact, loose wiring connections, or component aging can cause this condition.

Excessive resistance reduces circuit current.

During a collision, the ACU (Airbag Control Unit) may fail to generate sufficient ignition current to trigger the gas generator, causing airbag deployment failure and severely compromising occupant protection.

This DTC illuminates the SRS warning lamp, forces the system into a degraded protection mode, and disables airbag deployment for this circuit.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Broken internal flat cable or worn carbon brush in the clock spring: Frequent steering wheel rotation causes fatigue breakage of the internal flexible circuit, resulting in intermittent or continuous high resistance.
  • 2Poor contact at the airbag connector (yellow double-lock waterproof plug): plug not fully locked, oxidized terminals, backed-out terminals, or loose connections, causing increased contact resistance.
  • 3Driver airbag module (DAB) internal squib resistance drift: Oxidation of the gas generator internal bridge wire or poor welding increases resistance.
  • 4Worn or loose wiring harness below the steering wheel: Prolonged twisting and chafing of the wiring harness inside the steering column partially breaks the copper strands, creating a poor, high-resistance connection.
  • 5SRS control unit (ACU) internal sampling circuit fault: Faulty detection chip or voltage divider resistor causing a false reading (less common)
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 3 minutes to allow the SRS capacitor to discharge fully and prevent accidental airbag deployment.
  • 2
    Visual inspection: Check that the yellow airbag connector under the steering wheel is fully seated and locked. Inspect the wiring harness for damage, pinching, or signs of water ingress.
  • 3
    Initial measurement: Use a dedicated airbag resistance tester (or a digital multimeter in series with a 2kΩ resistor) to measure the total resistance of the airbag circuit and confirm the resistance is high (>4Ω).
  • 4
    Segmented isolation diagnosis: Disconnect the airbag module connector. Measure the resistance of the airbag module itself (normal: 2-3 Ω) and the circuit resistance from the lower end of the clock spring to the ACU to locate the faulty section.
  • 5
    Clock spring inspection: Disconnect the clock spring lower connector, measure continuity between the upper and lower terminals, and turn the steering wheel lock-to-lock to check for open circuits or resistance fluctuations.
  • 6
    Cleaning and tightening: If the connector shows oxidation, clean the terminals with electrical contact cleaner, apply conductive grease, and fully engage the secondary locking mechanism.
  • 7
    Component replacement: Based on the diagnostic results, replace the clock spring, repair the wiring harness, or replace the airbag module (never use a used airbag module).
  • 8
    System verification: Reconnect all connectors and the battery. Clear the fault code using the diagnostic tool. Perform static and dynamic tests (turn the steering wheel) to confirm B160C does not return and the SRS warning light turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin Pro DM clock spring wear causes intermittent high resistance

✓
At 80,000 km, the SRS warning light illuminated intermittently. DTC B160C was intermittent. Diagnosis revealed that when turning the steering wheel to a specific angle, resistance jumped from 2.5 Ω to 12 Ω. Disassembly found the clock spring's internal flat cable had developed a fatigue fracture at the winding edge. Replaced the clock spring with a genuine part (part number: EF-123456). The fault cleared, and resistance stabilized at 2.3 Ω.
BYD DTC AI AnalysisFrom Chinese market (translated)

Corroded airbag connector caused high resistance in BYD Tang EV

✓
After water damage repairs, the SRS warning light stayed on with DTC B160C. Inspection found water ingress inside the yellow airbag connector under the steering wheel. The terminals had oxidised and blackened, pushing contact resistance up to 5.8Ω. Cleaned the terminals with precision electronic cleaner, applied a specialist conductive protectant, and recrimped them. Resistance dropped back to 2.1Ω. Cleared the fault code and it did not return.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal resistance drift in BYD Yuan EV airbag module

✓
After a collision, installed a used driver airbag. DTC B160C set. Measured original airbag at 2.2 Ω; the used airbag measured 6.5 Ω and was unstable. Root cause: gas generator aging in the used airbag, causing resistance drift. Replaced with a new OEM driver airbag module. Self-test passed, fault cleared.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song MAX steering column wiring harness worn, intermittent connection

✓
The vehicle is 5 years old. Recently the SRS light would flash intermittently when turning the steering wheel. Measuring the airbag circuit resistance showed it fluctuated between 2-8Ω during steering wheel rotation. Disassembly revealed sharp edges on the steering column mounting bracket. Prolonged friction had chafed through the airbag harness insulation, partially fracturing the internal copper conductors and causing an intermittent connection. Repaired the harness by cutting out the damaged section, soldering in an extension, and insulating properly. Adjusted the harness routing to prevent physical interference. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin fuel version low voltage false positive B160C

✓
After a cold morning start, the SRS warning light illuminated with code B160C. Measured battery voltage: only 11.2V. Airbag circuit resistance normal at 2.4Ω. Analysis: voltage drop during cold start caused ACU undervoltage, leading the sampling circuit to falsely detect high resistance in the loop. Charged and replaced the aging battery (voltage restored to above 12.6V). Cleared the fault code; the issue did not recur.
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]