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B16E7-00

DTC B16E7-00 indicates the airbag system (SRS) detected a communication interruption or abnormal signal between the Middle Rear Impact Sensor and the SRS control module — Qin Plus

Safety System

DTC B16E7-00 indicates the airbag system (SRS) detected a communication interruption or abnormal signal between the Middle Rear Impact Sensor and the SRS control module.

This sensor typically mounts on a structural member in the middle rear of the vehicle (such as the lower C-pillar or rear panel crossmember) and monitors collision acceleration in the middle rear area.

The SRS module sets this DTC if it fails to receive a valid signal from the sensor within the specified time, or if it detects an open or short circuit in the wiring.

This fault may prevent the side curtain airbags, rear side airbags, or seat belt pretensioners from deploying correctly during a middle rear collision.

This severely compromises passive safety protection and continuously illuminates the instrument panel airbag warning light.

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Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Sensor wiring harness connector loose, oxidized, or experiencing water ingress: Because the center rear impact sensor mounts relatively low (typically on either side of the trunk or behind the rear seats), car washing, wading, or humid environments easily oxidize and corrode the connector pins, causing excessive contact resistance or signal interruption.
  • 2Crash sensor internal fault: A damaged internal accelerometer or processing chip cannot generate a valid crash signal, or CAN/LIN bus communication is abnormal.
  • 3Wiring harness open or short circuit: Incorrect harness connection after rear-end accident repairs, or harness chafing or rodent damage during long-term use, causing power, ground, or signal wire faults.
  • 4SRS control unit (ACU) interface fault: The internal interface circuit for the corresponding sensor in the airbag control module is damaged, preventing correct interpretation of the sensor signal.
  • 5Sensor mounting bracket deformed: Minor rear-end collision deforms the sensor mounting base, compromising sensor mounting or altering its alignment, triggering the internal fault monitoring circuit.
What To Do
  • 1
    Use VDS2000 or a dedicated BYD diagnostic tool to read the complete fault codes and freeze frame data. Confirm if the fault is current (Active) and record the vehicle status at the time of the fault. Check if other related crash sensor fault codes are also present.
  • 2
    Locate the center rear impact sensor (on Qin models, typically behind the upper middle of the rear seat backrest or inside the C-pillar trim panel). Remove the corresponding trim panel. Visually inspect the sensor for impact marks, cracks, or water stains. Verify the connector is fully seated and the retaining clip is intact.
  • 3
    Disconnect the battery negative terminal and wait 3 minutes (standard safety procedure). Unplug the sensor connector and use a multimeter to measure the harness-side terminals: check the supply voltage (typically 12V or 5V; refer to the wiring diagram), ground wire continuity (resistance must be less than 1Ω), and signal wire insulation to ground and power. Also measure the resistance between the sensor-side connector pins to check for an internal sensor short circuit.
  • 4
    Inspect the wiring harness routing. Check the harness passing through the trunk hinge and rear seat mounting points for wear, breaks, or crushing by foreign objects. If available, use an oscilloscope to test the signal waveform for interference or distortion.
  • 5
    If the wiring harness tests normal, replace the center rear impact sensor (verify the part number against the vehicle configuration, distinguishing between high-spec and low-spec sensor models). Install the sensor in the correct direction (the arrow on the sensor surface usually points toward the front of the vehicle) and tighten to the specified torque (usually 8-10 Nm).
  • 6
    Reconnect all components and the battery negative terminal. Clear the fault code using the diagnostic tool and perform the SRS system self-check (typically requires cycling the ignition switch three times or executing a specific diagnostic procedure). Confirm DTC B16E7-00 does not return and the airbag warning light is off. Perform a simulated crash test (using the diagnostic tool to execute the sensor test function) and verify the sensor data stream is normal.
Real-World Cases
BYD DTC AI Analysis

Centre rear collision sensor connector oxidised after driving through water

✓
The owner of a 2017 BYD Qin EV300 reported the airbag warning light stayed on after washing the car. The scan tool showed fault code B16E7-00 (current fault). We removed the left boot trim panel and found obvious water stains inside the center rear impact sensor connector, with the pins showing green oxidation. The boot seal had deteriorated, allowing high-pressure wash water to seep into the C-pillar area. We cleaned the connector pins with electronic cleaner, applied conductive grease to prevent corrosion, replaced the seal, and resolved the fault.
BYD DTC AI Analysis

Loose wiring harness connection after accident repair caused the fault

✓
2018 BYD Qin EV450. One week after rear-end collision repair, the instrument cluster showed an airbag fault. Scanned DTC B16E7-00. Inspection found that during the repair, the technician removed the rear bumper and rear panel, but when reinstalling did not fully insert the mid-rear impact sensor harness connector, leaving it half-plugged. Vibration from driving caused poor contact. Firmly reconnected the connector, secured it with waterproof tape, cleared the fault code, and the system returned to normal.
BYD DTC AI Analysis

Sensor internal circuit aging failure.

✓
A 2017 Qin 100 with 120,000 km developed an intermittent airbag warning light, with DTC B16E7-00 appearing intermittently. Inspected the wiring harness and connectors – all normal. Measured sensor supply and ground – normal. Replaced the centre rear impact sensor and the fault disappeared completely. Disassembled the old sensor and found the internal capacitor had leaked electrolyte, causing unstable accelerometer signal output. This is a common aging failure in sensors from early Qin production batches.
BYD DTC AI Analysis

Aftermarket parking sensor installation damaged the wiring harness

✓
While installing reversing sensors in the boot, the owner drilled too close to the centre rear impact sensor harness route. The drill bit cut into the harness, partially breaking the internal copper wires without completely severing them, causing an intermittent open circuit. This set DTC B16E7-00 sporadically. Repaired the damaged harness using heat-shrink tubing for insulation, and rerouted the reversing sensor wiring away from the factory harness.
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.