AU
B16EF00

DTC B16EF00 indicates the airbag control unit (SRS ECU) detected a communication interruption or open circuit in the Right Rear Impact Sensor — Seal U

Safety System

DTC B16EF00 indicates the airbag control unit (SRS ECU) detected a communication interruption or open circuit in the Right Rear Impact Sensor.

This sensor, typically installed inside the right rear door, C-pillar, or inner rear fender, monitors collision acceleration in the vehicle's right rear area.

The ECU determines a "not connected" state if it fails to receive a valid sensor signal (voltage signal or LIN bus data frame) within the specified period (typically 500ms), or if it detects circuit resistance outside the threshold (typically >10kΩ or <1Ω, depending on specific circuit design).

This safety-related fault can prevent the side airbag and side curtain airbag from deploying during a right rear collision.

The vehicle remains drivable, but the airbag system enters a degraded mode.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Loose sensor wiring harness connector or poor contact: The right rear impact sensor is located near the door or C-pillar. Frequent door operation or wading may loosen the 2-pin or 3-pin connector or oxidize the terminals, causing signal interruption.
  • 2Wiring harness open circuit or wear: Long-term bending of the right rear sill wiring harness at the seat slide rail, carpet trim strip, or door hinge breaks the internal copper strands while leaving the insulation intact (hidden open circuit), or wire routing during rear bumper modifications accidentally damages the sensor wiring harness.
  • 3Internal sensor body fault: damaged MEMS accelerometer chip, internal step-down circuit failure preventing operation, or sensor housing seal failure allowing water ingress and circuit board corrosion.
  • 4Poor contact at the SRS control unit connector: Oxidized or backed-out pins at the ECU plug located under the centre console or in the front compartment cause abnormal communication on a specific channel (right rear sensor channel).
  • 5Modification or collision repair issues: accidentally disconnecting and failing to reconnect the sensor connector when routing wires for an aftermarket reversing camera or dash cam, or failing to re-secure the sensor bracket after sheet metal repairs, causing wiring harness tension.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal. Wait at least 3 minutes for the SRS capacitor to fully discharge to prevent accidental airbag deployment. Read and record the DTC freeze frame data. Confirm the vehicle speed, timestamp, and other information from when the fault occurred.
  • 2
    Locate the sensor: Refer to the vehicle repair manual (usually inside the right rear C-pillar trim panel for Qin/Qin Pro, or inside the right rear quarter panel for E2/E3). Remove the interior trim panel or rear bumper. Visually inspect the right rear impact sensor (small black square unit with a 2-3 wire harness) and its white/yellow connector for looseness or water ingress.
  • 3
    Basic circuit check: Without unplugging the connector, use a multimeter to measure the voltage on the sensor harness side (normal reading is a 2.5-3.3V reference voltage or 5V supply, depending on the sensor type). A voltage of 0V or 12V indicates a circuit short to ground, a short to power, or an ECU fault.
  • 4
    Continuity test: Disconnect the SRS ECU and sensor connectors. Measure the wiring harness continuity resistance between both ends (should be <1Ω) and insulation resistance (should be >10MΩ). Inspect the sill wiring harness for pinch marks or breaks at the routing hole below the B-pillar.
  • 5
    Sensor replacement verification: If wiring is normal, replace the crash sensor with the same model (verify the part number, such as the 102... or 6A... series). Temporarily connect the sensor, power on, and clear the fault code. Perform a sensor self-check (wait 10 seconds and observe if the fault code reappears).
  • 6
    System reset and road test: After verifying fault resolution, reinstall all interior trim panels, connect the battery, and use the VDS2000/BYD diagnostic tool to perform "SRS system configuration" and "crash sensor zero-point calibration" (required on some models). Clear the fault codes, perform a 5-10 km road test, and read the live data stream using the diagnostic tool. Verify the right rear sensor acceleration value (G value) shows normal slight fluctuations (0.00-0.05G) over road bumps, with no communication interruption records.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM airbag warning light on after water entered right rear door

✓
2019 Qin Pro DM. After heavy rain, the airbag warning light remained on. Retrieved fault code B16EF00. Removed the right rear C-pillar trim panel and found water inside the impact sensor connector; terminals had oxidized and turned green. Cleaned the connector with electrical contact cleaner, applied conductive grease, dried the wiring harness with compressed air, and reconnected. Fault cleared. Check the door seal drainage holes for blockages to prevent water ingress.
BYD DTC AI Analysis

E2 ride-hailing car: Aftermarket reverse camera installation accidentally cut the wiring harness.

✓
2020 BYD E2 ride-hailing vehicle. After having a reversing camera installed at an auto parts market, the instrument cluster displayed an airbag warning. The diagnostic tool logged DTC B16EF00. Inspection found the installer had disconnected the crash sensor connector when removing the right rear quarter panel trim and did not push it back in fully. The wiring harness was pinched beneath a trim clip and nearly severed. Repaired the harness, properly reconnected the connector, and secured the loom with cable ties away from the clip. Fault cleared.
BYD DTC AI Analysis

Qin EV sensors not initialized after accident repair

✓
2019 BYD Qin EV. Minor collision on the right rear. A repair shop replaced the rear bumper and right rear quarter panel. After the repair, the airbag warning light illuminated with DTC B16EF00. Inspection revealed a new impact sensor had been installed, but the zero-point calibration was not performed. Using the BYD VDS diagnostic tool, the technician performed the "Right Rear Impact Sensor Zero-Point Calibration" procedure, cleared the fault codes, and the system returned to normal.
BYD DTC AI Analysis

BYD Qin Pro (petrol) - hidden open circuit in door sill wiring harness

✓
2018 BYD Qin Pro petrol variant. The airbag warning light illuminated intermittently on rough roads; the scan tool showed intermittent B16EF00. Static circuit measurements were normal, but the fault reappeared when shaking the harness. Removed the right front seat and sill trim and found the harness had chafed against the seat rail mounting bracket—internal copper conductors were 80% broken, with only minimal contact remaining. Cut out the damaged harness section, soldered the joint and insulated it with heat-shrink tubing, then re-routed the wiring clear of moving parts. Fault eliminated.
BYD DTC AI Analysis

E3 sensor internal circuit damaged

✓
2020 BYD E3, no accidents or modifications. Suddenly logged DTC B16EF00. Sensor supply voltage measured 2.8V – normal. Ground connection normal, but no signal waveform on the LIN line. Replaced the sensor, but the fault remained. Further inspection found the original sensor had an internal short that damaged the channel driver chip inside the SRS ECU. Replaced the SRS control unit (requires replacing or rewriting the airbag configuration code) and the collision sensor. 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.