AU
B16471B

DTC B16471B indicates the driver-side seatbelt pretensioner circuit resistance exceeds the normal threshold set by the SRS control module (typical normal range: 1 — Atto 3

Safety System

DTC B16471B indicates the driver-side seatbelt pretensioner circuit resistance exceeds the normal threshold set by the SRS control module (typical normal range: 1.5-4.0 Ω; detected value is high).

The pretensioner is a pyrotechnic component of the passive safety system, containing a resistance wire and an igniter charge.

Excessive resistance indicates high circuit impedance resulting from poor contact, wiring harness oxidation, connector corrosion, or pretensioner aging.

This fault forces the SRS system into a degraded mode and continuously illuminates the airbag warning light.

During a collision, the driver-side seatbelt pretensioner may fail to deploy and retract, severely compromising occupant restraint protection.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1A loose connection, backed-out terminals, or oxidized pins at the yellow pretensioner connector under the driver's seat (usually marked D+, D-) increase contact resistance. This is the most common cause, especially after frequent fore-and-aft seat adjustment or driving through water.
  • 2Internal slip ring wear in the clock spring (spiral cable) or poor contact in the ribbon cable causes unstable or excessively high resistance in the pretensioner signal circuit.
  • 3Aging, breakage, or moisture corrosion of the internal resistance wire in the seat belt pretensioner unit causes resistance to exceed the tolerance range (typically 5-10 Ω or higher).
  • 4Floor wiring harness worn, broken, and reconnected near the seat slide rail, or aftermarket modifications (such as seat heating/ventilation) causing series resistance in the wiring.
  • 5SRS control module internal sampling circuit fault or software calibration drift causing the module to misjudge normal resistance as abnormal (compare left and right resistance values to confirm)
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal, wait at least 3 minutes for the SRS capacitor to discharge, disable the airbag system, and wear an anti-static wrist strap.
  • 2
    Visual inspection: Verify the yellow SRS connector under the driver's seat is fully locked. Inspect the terminals for green corrosion, burning, or backed-out pins. Check the wiring harness for wear at the seat slide rail.
  • 3
    Resistance measurement: Disconnect the pretensioner connector. Measure the resistance between the pretensioner terminals using a digital multimeter (Fluke or similar low-current meter). Normal resistance is 2.0-3.0 Ω. If the resistance exceeds 4.5 Ω, the pretensioner is faulty.
  • 4
    Harness continuity test: Measure harness continuity from the pretensioner connector to the SRS ECU (usually located under the centre console or in the front compartment). Verify continuity at each clock spring pin (if the pretensioner connects through the clock spring).
  • 5
    Cleaning and repair: If oxidation is present, treat the pins with electrical contact cleaner, apply conductive grease, and verify the connector locking tab is intact. If the wiring harness is damaged, repair it using the dedicated yellow high-temperature wiring harness. Do not simply twist the wires together.
  • 6
    Component replacement: If the pretensioner body resistance is abnormal, replace the driver seat belt assembly (including the pretensioner). After replacement, use a dedicated diagnostic tool (such as BYD VDS or Launch X431) to perform "Airbag Configuration" and "Resistance Learning".
  • 7
    System verification: Clear the fault code, turn the ignition switch to ON, and verify the SRS warning lamp turns off after the self-check. Use a diagnostic tool to read the data stream and confirm the pretensioner resistance is within the normal range. Perform a simulated crash test (if the equipment supports it).
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

The connector under the seat oxidized, causing resistance drift.

✓
The vehicle came in with the airbag warning light on. Read DTC B16471B. Found the yellow connector under the driver's seat showed water damage, with oxidised and blackened pins. Cleaned it with WD-40 Precision Electrical Contact Cleaner, reducing resistance from 5.2Ω to 2.3Ω. Fault resolved. Advised the customer to avoid spraying water directly under the seats when washing the car and to waterproof the connector.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal open circuit in clock spring causes false alarm.

✓
BYD Qin Pro DM. Customer reported the airbag warning light illuminating intermittently. Pretensioner resistance measured normal. Resistance from the clock spring to the SRS ECU was unstable, fluctuating between 2–8 Ω. Disassembled the steering wheel and found a broken internal ribbon cable in the clock spring. Replaced the clock spring; resistance stabilised at 2.1 Ω. Cleared fault codes; the fault has not returned.
BYD DTC AI AnalysisFrom Chinese market (translated)

Aftermarket seat heater installation caused abnormal circuit resistance.

✓
Owner installed seat heating pads, splicing into the wiring to connect power. During the work, the owner accidentally damaged the pretensioner harness insulation, causing the copper wires to oxidise. Inspection found extra resistance spliced into the pretensioner circuit. Repaired the wiring (replaced the entire section of yellow SRS-specific cable) and removed the illegal heating pad wiring. Resistance measurements returned to normal and the SRS system resumed normal operation.
BYD DTC AI AnalysisFrom Chinese market (translated)

Pretensioner internal resistance high due to aging

✓
2018 Qin Pro, 5 years old. DTC B16471B wouldn't clear. Disconnected the pretensioner plug and measured the pretensioner's resistance directly: 6.8Ω, well above spec. Diagnosed an aged pyrotechnic resistor wire inside the pretensioner. Replaced the driver-side seat belt assembly (including pretensioner). Performed the 'Replace Pretensioner' configuration with VDS2000. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

SRS control module software misdiagnosis

✓
No accident history. Measured resistances of the pre-tensioner and harness were both within the normal range (2.4Ω), but code B16471B appeared frequently. Compared to the passenger side resistance (2.2Ω), the difference was minimal. Upgraded the SRS control module software to the latest version (2023 patch); the fault code did not return. Determined to be a false trigger caused by overly sensitive calibration in the early software.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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]