AU
B16F100

DTC B16F100 indicates an internal electrical fault or signal plausibility error in the right (passenger side) Side Impact Sensor (SIS) — Seal U

Safety System

DTC B16F100 indicates an internal electrical fault or signal plausibility error in the right (passenger side) Side Impact Sensor (SIS).

This sensor typically mounts inside the right B-pillar trim panel or right front door cavity.

It monitors the acceleration change rate (Delta-V) during a side impact and transmits an analog voltage signal (normal range 0.4-4.6V) to the SRS airbag control unit via the LIN bus or a hardwired connection.

Fault trigger conditions include internal accelerometer self-test failure, signal voltage continuously outside thresholds (too high/too low), sensor ID verification failure, or communication loss with the SRS module.

This fault prevents the right side airbags and side curtain airbags from deploying correctly during a side impact, or forces the airbag system into a degraded protection mode (retaining only the driver's front airbag function).

This is a safety-critical fault requiring immediate repair.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1A damaged piezoelectric accelerometer element or failed signal processing chip inside the right side impact sensor causes the output signal to drift or remain at a fixed voltage.
  • 2Water ingress and oxidation in the sensor wiring harness connector (commonly due to rainwater intrusion from poor sealing at the lower right B-pillar or aging window seals), causing a short to ground in the power or signal wire.
  • 3Internal copper wires in the right front door wiring harness break at the hinge bend (metal fatigue from frequent door opening and closing), causing an intermittent open circuit in the sensor power supply or communication lines.
  • 4Installing a new sensor without coding and configuration after repairing right-side accident damage (on some BYD models, replacing the sensor requires using VDS to perform 'Crash Sensor ID Configuration' and 'Zero Point Calibration').
  • 5Internal fault in the SRS control unit sampling circuit preventing correct identification of the right sensor signal, or deformed sensor mounting bracket causing the sensor mounting angle to deviate beyond the allowable range of ±5°.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 3 minutes to allow the SRS capacitor to fully discharge. Remove the service disconnect switch (if equipped with a high-voltage system). Use the VDS2000/VDS2100 diagnostic tool to read the complete DTC snapshot. Record the vehicle speed, sensor voltage values, and freeze frame data at the time of the fault.
  • 2
    Physical inspection: Remove the right B-pillar lower trim panel (remove the door sill trim panel first). Check the crash sensor connector (part number usually starts with 5A or 6A) for looseness, water ingress (look for green oxidation), or backed-out pins. Inspect the sensor mounting bracket for deformation. Verify the fixing bolt torque is 7-9 N·m.
  • 3
    Circuit measurement: Keep the sensor disconnected. Measure the harness-side connector: power pin (usually IG+) to ground voltage should be 9-16V (ignition ON), ground pin resistance should be <1Ω, and signal wire (LIN or PWM) to ground static voltage should be approximately 2.5V (depending on vehicle model). Inspect the right front door hinge wiring harness for breaks.
  • 4
    Component swap verification: If the wiring is normal, disconnect power and swap the right-hand sensor with the left-hand sensor (verify the part numbers match). Restore power, clear the fault code, and perform a road test or simulate vibration. If the fault code changes to B16E100 (left-side impact sensor fault), this confirms an internal fault in the original right-hand sensor.
  • 5
    Replacement and configuration: After installing the new sensor, some models (such as Qin Pro) require a diagnostic tool to execute the 'SRS Sensor Configuration' function, write the sensor serial number, and perform a 'Longitudinal/Lateral Zero Point Calibration'. Upon completion, run a system self-diagnosis and confirm the B16F100 status is 'History' or 'None'.
  • 6
    Final verification: Restore all connections, reconnect the battery, and start the vehicle. Observe if the airbag warning light turns off (it should turn off after the self-test). Perform a right crash sensor signal simulation test (some diagnostic tools support this) and confirm the SRS control unit correctly receives the sensor acceleration signal.
Real-World Cases
BYD DTC AI Analysis

Water ingress at right B-pillar caused sensor pin corrosion

✓
2019 BYD Qin Pro DM. Owner reported the airbag warning light stayed constantly illuminated after wading through water in heavy rain. The scan tool displayed active fault code B16F100. Removed the right B-pillar trim panel and found significant copper oxide corrosion inside the side impact sensor connector. Insulation resistance between pin 1 (12V supply) and pin 3 (ground) measured only 200 Ω. Cleaned the connector terminals with electrical contact cleaner and inspected the B-pillar drain hole for blockages. Cleared the drain hole; fault resolved. Recommend checking door seal integrity.
BYD DTC AI Analysis

Sensor configuration not performed after accident repair.

✓
2018 Qin Pro petrol variant. Following right-side collision repairs, replaced the right front door and B-pillar inner panel, and fitted a new impact sensor. Post-repair VDS scan showed B16F100 (current fault). Checked sensor power and ground – normal. Wiring harness continuity good. Reviewed repair records: replacement sensor part number matched the original, but the technician had not performed the configuration procedure. Used VDS to access SRS system → Special Functions → Impact Sensor Configuration. Selected 'Right Side Sensor' and followed the prompts to complete ID writing and zero-point calibration (vehicle must be on level ground with the steering wheel centred). Configuration completed, fault code cleared automatically, system returned to normal.
BYD DTC AI Analysis

Internal break in right front door wiring harness at hinge point

✓
2019 BYD Qin Pro DM. Customer reported intermittent airbag warning light, especially after opening or closing the right front door. Diagnostic scan tool retrieved stored DTC B16F100. Static measurement showed normal sensor supply voltage, but lightly shaking the right front door harness caused the signal wire (LIN bus) voltage to ground to swing between 0 V and 5 V. Stripped back the corrugated tube at the right front door hinge and found the internal copper strands of the harness fractured at the bend — only the outer insulation remained holding the ends together (metal fatigue from frequent door operation). Resoldered the broken pink signal wire, applied double-layer heat‑shrink tubing for waterproofing, and secured the harness routing to prevent repeated flexing. Fault eliminated.
BYD DTC AI Analysis

Sensor mounting bracket deformation causing abnormal signal

✓
2018 Qin Pro. The right-side B-pillar was deformed by a side impact. An independent shop performed body repair but did not replace the sensor. Several months later, DTC B16F100 appeared. Inspection found the sensor mounting bracket had stretched and deformed during the repair, shifting the sensor mounting angle approximately 15° (beyond the permitted ±5° tolerance) and causing an incorrect internal accelerometer reference position. Replaced the B-pillar inner panel (including sensor bracket) and the impact sensor, torqued to specification, and performed zero-point calibration. Fault resolved.
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.