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B16F300

DTC B16F300 indicates an abnormal communication link between the airbag control unit (SRS ECU) and the Rear Right Impact Sensor — Qin Plus

Safety System

DTC B16F300 indicates an abnormal communication link between the airbag control unit (SRS ECU) and the Rear Right Impact Sensor.

This sensor typically uses a LIN bus or a dedicated digital communication protocol to exchange data with the SRS ECU to monitor collision acceleration on the rear right side of the vehicle.

The ECU sets this communication fault when it fails to receive a valid data frame from the sensor within the specified time or receives data with a checksum error.

This fault causes the SRS system to enter a degraded mode and disables the rear right collision detection function.

In extreme cases, it may affect the correct deployment timing of the side airbags/side curtain airbags.

This is a safety-related fault.

5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Poor contact, loose connection, or oxidized terminals at the right rear crash sensor wiring harness connector, interrupting signal transmission.
  • 2Internal sensor circuit fault (e.g., chip damage or water ingress corrosion) preventing response to ECU communication requests.
  • 3Wiring harness open or short circuit (especially a crushed or cut harness following rear-end collision repairs).
  • 4Altered sensor mounting position or deformed mounting bracket causes physical interference with sensor-to-ECU communication.
  • 5SRS control unit internal communication module fault (less common; usually occurs with other sensor communication faults)
What To Do
  • 1
    Use VDS2000 or a dedicated BYD diagnostic tool to read all fault codes, confirm B16F300 is a current fault and fails to clear, and check for related historical fault codes.
  • 2
    Visually inspect the right rear crash sensor (usually located at the C-pillar, rear fender liner, or rear panel). Verify the sensor has no physical damage or signs of water ingress, the mounting bracket is not deformed, and the fixing bolt torque meets the standard (usually 8-10 N·m).
  • 3
    Disconnect the battery negative terminal and wait at least 90 seconds for the SRS capacitor to fully discharge. Disconnect the right rear crash sensor connector. Check the terminals for oxidation, backed-out pins, or deformation. Clean or repair as necessary.
  • 4
    Measure at the sensor wiring harness connector using a multimeter: check the power supply voltage (should be battery voltage, 9-16V), LIN line voltage (static approx. 12V, pulsing approx. 8-10V during communication), and ground resistance (should be less than 1Ω). Verify the wiring harness has no short to ground or power.
  • 5
    Measure the sensor body resistance (refer to the workshop manual for the standard value, typically several hundred to several thousand ohms). If the resistance is abnormal or infinite, replace the right rear crash sensor (match the part number to the vehicle configuration).
  • 6
    If the wiring harness and sensors are normal, perform a sensor swap test (swap the left and right rear sensors). Observe if the fault code transfers to determine whether the fault lies with the sensor, the ECU, or the wiring harness.
  • 7
    After repairing or replacing the faulty component, reconnect all connectors and the battery. Use the diagnostic tool to clear the fault code. Perform an SRS system self-test and verify B16F300 does not return. Finally, perform a road test to verify the repair.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM: Right rear sensor loses communication after wading

✓
A 2019 Qin Pro DM displayed the airbag warning light on the instrument cluster after driving through heavy flood water. The scan tool recorded current fault code B16F300. Inspection found that water had entered the right rear impact sensor, located at the lower C-pillar, during wading because the door seal had deteriorated. Disassembly showed corrosion on the sensor's internal circuit board and water staining in the wiring harness connector. Replaced the right rear impact sensor, cleaned the harness connector and applied conductive grease, and replaced the C-pillar seal. No recurrence after one month of monitoring post-repair.
BYD DTC AI Analysis

Poor wiring harness connection after accident repair

✓
2018 BYD Qin Pro (petrol). Minor right-rear collision. After an external shop repaired the right rear quarter panel, DTC B16F300 set. During the repair the shop did not correctly install the wiring harness retaining clips. The harness rubbed against a body metal edge, wearing through the insulation and partially fracturing the copper wires, causing an intermittent connection. Repair: cut out the damaged section, soldered the wires, sealed with heat shrink tubing, then re-routed and secured the harness to standard specifications to eliminate stress points. Cleared the DTC and communication returned to normal.
BYD DTC AI Analysis

Oxidized sensor connector causing intermittent communication error

✓
Owner reported intermittent airbag warning light. Diagnostic tool showed intermittent fault code B16F300. Inspected the right rear impact sensor connector – terminals had obvious oxidation from long-term coastal driving and salt spray corrosion. Measured LIN bus voltage at approximately 6V, abnormally low. Cleaned the terminals with electrical contact cleaner, applied antioxidant protective coating, and replaced the connector housing where necessary. Intermittent fault disappeared after repair.
BYD DTC AI Analysis

Aftermarket reversing camera installation pinched the wiring harness

✓
2019 BYD Qin Pro DM. Owner self-installed a reversing camera. Routing the wiring through the right rear interior trim panel inadvertently pinched the right rear impact sensor harness, causing an intermittent short between the LIN line and ground wire. The airbag warning light came on at startup and occasionally went out while driving. Inspection found a screw-fixed clip inside the C-pillar trim had crushed the harness. Repaired the damaged harness and rerouted the wiring to proper specification, avoiding the original harness routing path. Fault resolved.
BYD DTC AI Analysis

Outdated SRS ECU software caused false alarms

✓
Multiple 2018 Qin Pro vehicles intermittently triggered B16F300 fault codes in low temperatures (below -10°C). Inspection of the wiring harness and sensors found no issues. Per the manufacturer's technical bulletin, early SRS control unit software set communication protocol fault tolerance thresholds too strictly, and would report errors when cold caused slight signal delays. Solution: Upgrade the SRS control unit software to the latest version (verify the correct version number for the specific vehicle model). After upgrading, communication stability in low temperatures improved and the fault has not recurred.
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.