AU
B16F300

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

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.

The B16F300 fault code on the Seal U indicates an abnormal communication link between the SRS airbag ECU and the rear right impact sensor. Severity is medium because it can reduce rear right crash detection and may affect side airbag timing. Common causes include a loose or corroded sensor connector or an internal sensor fault from damage or water ingress. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Poor contact, loose connection, or terminal oxidation at the right rear crash sensor wiring harness connector, interrupting signal transmission.
  • 2Internal sensor circuit fault (such as chip damage or corrosion from water ingress) preventing response to ECU communication requests.
  • 3Wiring harness open or short circuit (especially after rear collision repairs, which may crush or cut the harness).
  • 4An altered sensor mounting position or deformed mounting bracket physically interferes with communication between the sensor and the ECU.
  • 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 that cannot be cleared. Check for related history fault codes.
  • 2
    Visually inspect the right rear crash sensor (usually located at the C-pillar, rear fender liner, or rear body panel) to confirm no physical damage, no signs of water ingress, no mounting bracket deformation, and that the mounting 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 discharge. Disconnect the right rear crash sensor connector and check the terminals for oxidation, backed-out pins, or deformation. Clean or repair as necessary.
  • 4
    Measure at the sensor wiring harness connector with a multimeter: check the power supply voltage (should be battery voltage, 9-16V), LIN line voltage (approximately 12V static, pulsing at approximately 8-10V during communication), and ground resistance (should be less than 1Ω). Verify the wiring harness has no short to ground or short to power.
  • 5
    Measure 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 (the part number must match 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 whether the fault code transfers to determine if the fault lies with the sensor, ECU, or 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-check and confirm 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

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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

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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

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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

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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

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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 Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U overview →
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.