AU
B16F0

This DTC indicates an abnormally low-resistance connection between the Supplemental Restraint System (SRS) Right Rear Impact Sensor signal circuit and body ground — Qin Plus

Safety System

This DTC indicates an abnormally low-resistance connection between the Supplemental Restraint System (SRS) Right Rear Impact Sensor signal circuit and body ground.

In the BYD SRS architecture, impact sensors utilize a dual-axis accelerometer design, transmitting a 0-5V analog voltage signal to the Airbag Control Unit (ACU) via hardwire.

A short to ground continuously pulls the signal line voltage down to <0.5V (normal static voltage is approximately 2.5V).

The ACU sampling circuit detects this abnormal voltage level and triggers the DTC.

This fault forces the SRS into fail-safe mode, disabling the right rear side airbag and curtain airbag deployment while illuminating the airbag warning lamp.

Because the short circuit can occur anywhere in the wiring harness, excessive short-circuit current (>2A) risks burning out the internal ACU drive circuit.

This single-point failure directly compromises the vehicle's side-rear collision detection capability and, in extreme cases, prevents airbag deployment during a collision.

5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Long-term vibration chafes the right rear impact sensor wiring harness at the C-pillar or rear seat mounting bracket. Damaged insulation causes the signal wire to contact body ground. This commonly occurs on vehicles with >50,000 km.
  • 2Aged sealing ring or loose retaining clip on the sensor connector (usually located inside the right rear quarter panel). Water ingress after washing the vehicle or driving through water causes electrolytic corrosion between the pins, forming a short-to-ground path.
  • 3Internal breakdown of the crash sensor ASIC chip causes an internal short circuit between the signal output terminal and the metal housing (ground), typically resulting from external impact or electrical overstress.
  • 4During rear-end accident repairs, improper wiring harness routing causes trim panel clips to pinch the harness, or metal clamps cut the harness insulation, causing a hidden short circuit.
  • 5A damaged ADC channel in the internal sampling circuit of the SRS control unit (ACU), or reference voltage drift, causes a false sensor short-to-ground fault (rule out by cross-checking).
What To Do
  • 1
    Use VDS2000 or a dedicated BYD diagnostic tool to read fault codes. Confirm B16F0 is a Current DTC, not a historical fault. Record environmental parameters such as vehicle speed and temperature from the freeze frame data.
  • 2
    Perform the safe power-down procedure: Disconnect the 12V battery negative terminal and wait at least 90 seconds for the SRS capacitor to fully discharge. Do not operate any electrical equipment during this time.
  • 3
    Remove the right rear C-pillar trim panel and rear seat side trim panel. Locate the right rear impact sensor (usually marked 'SIS RR' or 'SENSOR, SIDE IMPACT REAR RIGHT') and verify the part number is a genuine BYD component (e.g., 5A-XXXXXX series).
  • 4
    Visual inspection: Check the sensor body for physical damage. Inspect the connector for obvious signs of water ingress (white powdery corrosion) and bent or backed-out pins. Check the wiring harness corrugated conduit for damage where it passes through the sheet metal hole.
  • 5
    Disconnect the sensor connector and use a digital multimeter to measure the resistance between the sensor-side signal pin (usually Pin 2) and the sensor housing. Normal resistance is open circuit (>10MΩ). If continuity exists (<1Ω), replace the sensor assembly.
  • 6
    Measure the insulation resistance between the harness-side signal wire and ground: >1MΩ. If the resistance is too low, troubleshoot along the harness routing using the half-split method. Specifically check if the harness protective sleeve is worn through at the floor crossmember and seat slide rail mounting points.
  • 7
    If the wiring harness insulation is normal, turn the ignition ON and measure the voltage at the sensor signal pin on the ACU side. The voltage should be the 5V reference voltage (±0.25V tolerance). If the voltage is 0V, an internal ACU short circuit may exist. Measure the resistance between this pin and ground to confirm.
  • 8
    When repairing the wiring harness, double-wrap it with high-temperature tape (125°C grade) and install a rubber grommet at the pass-through hole. When replacing the sensor, tighten to the standard torque (usually 8-10 N·m) and seat the sensor tightly against the vehicle body metal surface to accurately transmit vibration.
  • 9
    Reconnect all connectors (confirm the locking 'click'), reinstall the trim panels, connect the battery, use the diagnostic tool to clear the fault code, and perform the 'SRS system self-check' procedure.
  • 10
    Perform function verification: Access the data stream and read 'Right Rear Impact Sensor Status'. Lightly tap the right rear side panel with a rubber mallet to simulate collision vibration. Confirm the sensor output voltage changes accordingly (2.5V→0V or 5V pulse) and the diagnostic tool generates no new fault codes.
Real-World Cases
BYD DTC AI Analysis

Corroded sensor connector on water-wading vehicle caused short circuit

✓
A 2019 BYD Yuan EV with 42,000 km on the clock came in with the airbag warning light permanently on. Scanning revealed current fault code B16F0. Inspection found visible water staining inside the connector of the right rear impact sensor, located at the lower C-pillar. Pins 1 (earth) and 2 (signal) showed green copper corrosion, and resistance between them measured only 0.3 Ω. Investigation traced the cause to the vehicle wading through water deeper than the door sill one month earlier, allowing water to seep in through the wiring harness grommet. Replaced the sensor (internally corroded), cleaned the connector with electronic contact cleaner, fitted a new waterproof seal, and applied waterproof sealant to the sensor mounting base. This cleared the fault. Advised the owner to check the sealing condition of other low-mounted sensors.
BYD DTC AI Analysis

Wiring harness pinched after accident repairs, causing intermittent short

✓
A 2021 BYD Tang developed a B16F0 DTC one week after an accident repair to the left rear quarter panel. Service history showed the left rear wing had been replaced. Investigation revealed that technicians had incorrectly routed the right rear impact sensor wiring harness (which runs parallel to the left rear side harness) beneath the seat mounting bracket. The metal bracket edge cut through the corrugated tubing and crushed the wire insulation, causing the signal wire to short to ground against the bracket. The pinch point was concealed inside the seat rail, making it hard to catch during a routine visual inspection. Repair steps: Released the seat mounting bolts, removed the damaged harness, cut out the damaged section (approximately 15 cm), fused in replacement wiring by soldering (twist connections prohibited), insulated with double-layer heat shrink tubing, and rerouted the harness away from sharp metal edges. The fault was completely resolved.
BYD DTC AI Analysis

Thermal breakdown of the sensor's internal ASIC chip

✓
2019 BYD Song MAX, 68,000 km. Intermittent airbag warning light, DTC B16F0 (intermittent). Initial inspection: wiring harness insulation normal, connectors normal. Used an oscilloscope to monitor the sensor signal line; found intermittent short-to-ground pulses on rough roads. Disassembled the sensor; found slight burn marks on the bottom of the MEMS accelerometer chip on the internal PCB. Determined that long-term high-temperature exposure (sensor mounted on C-pillar metal panel; summer cabin temperatures exceed 70°C) caused breakdown of the chip's internal signal conditioning circuit. Repair: Replaced right rear impact sensor (part number varies by production date). Installed a heat insulation pad (included in OEM repair kit) between the new sensor and body mounting surface to keep sensor operating temperature below 85°C.
BYD DTC AI Analysis

Aftermarket sensor compatibility issue

✓
2020 Qin petrol variant. After an unauthorised repair shop replaced the right rear impact sensor, DTC B16F0 appeared. Multimeter testing revealed a fixed resistance of approximately 200 Ω between the signal output terminal and housing on the aftermarket sensor; a genuine sensor should read high impedance. The cause was an internal circuit design defect in the aftermarket part—the signal output stage lacked complete isolation. Solution: Replaced with a genuine BYD sensor (verify part number via VDS), cleared the fault code, and the fault disappeared. Impact sensors must be genuine OEM parts. Aftermarket units can cause false triggering or functional failure due to mismatched electrical parameters.
BYD DTC AI Analysis

Wiring harness sheath wear caused intermittent short circuit

✓
2019 Yuan, 55,000 km. Airbag warning light illuminated intermittently. DTC B16F0 status: History/Intermittent. Inspection found the right rear collision sensor harness chafing where it passes through the floor-to-C-pillar junction. Repeated trunk opening and closing flexed the harness repeatedly, wearing through the corrugated tubing and abrading the wire insulation. This caused intermittent contact with the body panel when the vehicle vibrated. Insulation resistance tested with a megohmmeter showed normal readings at rest, but resistance dropped to <100 Ω when bending the harness. Repair: Cut out the worn harness section (approx. 20 cm), re-routed the wiring, added securing clips to prevent body panel contact, and fitted braided sleeving for extra protection.
Other Qin Plus 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.