AU
B16EF

DTC B16EF indicates the SRS (Supplemental Restraint System) control module detects a communication interruption or missing physical connection with the Right Rear Impact Sensor — Seal U

Safety System

DTC B16EF indicates the SRS (Supplemental Restraint System) control module detects a communication interruption or missing physical connection with the Right Rear Impact Sensor.

This sensor typically mounts in the right C-pillar, rear door frame, or inside the right rear quarter panel to monitor collision acceleration changes on the right rear side of the vehicle.

During a side-rear collision, the sensor transmits the acceleration signal to the SRS module to determine whether to deploy the right curtain and side airbags.

A "not connected" fault means the SRS module cannot detect the sensor during initialization or periodic communication checks.

Causes include an open circuit, disconnected connector, internal sensor open circuit, or abnormal module power supply.

This fault disables the right rear collision protection function.

As a safety-critical fault, it requires immediate repair.

The B16EF fault code on the Seal U indicates the SRS control module cannot communicate with, or detect, the right rear impact sensor. This is a medium-severity safety fault because it can disable right rear side or curtain airbag protection. Common causes include a loose sensor connector, backed-out terminal, damaged wiring, or a short in the rear sill/C-pillar harness. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
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Causes
Likely Causes — Seal U
  • 1Sensor wiring harness connector loose, terminal backed out, or poor contact: commonly caused by incomplete seating after accident repairs or long-term vibration loosening the retaining clip.
  • 2Wiring harness open or short circuit: The right rear sill and C-pillar wiring harness breaks after water exposure, accidents, or long-term bending. Rodent damage or metal edge chafing causes a short to ground or power.
  • 3Internal fault in the sensor body: Damage to the internal piezoelectric element or processing circuit causes no signal output or a power supply short circuit.
  • 4SRS control module power supply or communication fault: a faulty module IGN power supply, ground circuit, or CAN bus communication circuit prevents sensor recognition.
  • 5Sensor installation/configuration error: Failed to write the configuration code (VIN matching or sensor position learning) after replacing the sensor, or installed a sensor with an incorrect part number.
What To Do
  • 1
    Safety preparation and fault confirmation: Disconnect the 12 V battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor. Use VDS2000 or a BYD dedicated diagnostic tool to read fault codes. Confirm B16EF is a current fault (ACTIVE), not a historical fault. Verify the 'Right Rear Impact Sensor Status' in the data stream shows 'Disconnected' or 'Communication Failure'.
  • 2
    Physical connection check: Remove the right C-pillar interior trim panel or rear door sill trim panel and locate the right rear impact sensor (usually a yellow connector). Verify the connector is fully inserted. Inspect for broken locking tabs and backed-out or corroded terminals. Check the sensor mounting bracket for deformation or looseness.
  • 3
    Harness continuity and voltage measurement: Disconnect the sensor connector and SRS module connector. Measure harness end-to-end continuity (should be less than 1 Ω). Measure power wire voltage to ground (should be 12 V battery voltage). Measure ground wire resistance to ground (should be less than 1 Ω). Check the signal wire for a short to power or ground.
  • 4
    Sensor body inspection: If the wiring harness is normal, measure the sensor body resistance (refer to the workshop manual; typically several kilo-ohms to tens of kilo-ohms, depending on the specific model). If the resistance is infinite or zero, replace the sensor. Inspect the sensor exterior for physical cracks or signs of water ingress.
  • 5
    Replacement and restoration: After installing a new sensor or repairing the wiring harness, listen for a 'click' to confirm the connector latch locks. Reconnect the battery, use the diagnostic tool to clear the fault code, and perform an 'SRS system self-check' or 'crash sensor configuration' (some models require writing the configuration code or performing sensor position learning).
  • 6
    Verification test: Start the vehicle and confirm the SRS warning lamp turns off; read the data stream and confirm the sensor status displays 'Normal'; perform a tap test (lightly tap the sensor mounting area and observe the data stream for acceleration value changes) to confirm system function has returned to normal.
Real-World Cases
BYD DTC AI Analysis

BYD Tang DM: Backed-out pin in right rear collision sensor connector causing intermittent fault

✓
The SRS warning light occasionally came on while driving and turned off after restarting. A VDS scan showed intermittent DTC B16EF. Inspected and found the sensor connector inside the right C-pillar trim was plugged in, but the terminals had backed out due to a previous improper repair, causing poor contact when driving over bumps. Re-crimped the terminals, applied conductive paste, and locked the connector fully. The fault has not reappeared.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX: Open circuit in right rear impact sensor wiring harness after accident repair

✓
The vehicle had a right rear side scrape. After repairs at a workshop, the SRS warning light stayed on. Diagnosis showed current fault B16EF. Inspection revealed the accident had crushed and severed the wiring harness inside the right rear sill, breaking both power and signal wires. Repaired the harness by soldering and sealing with heat shrink tubing, rerouted the wiring to prevent chafing against metal edges, and cleared the fault codes. System returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Yuan EV right rear impact sensor internal short circuit after wading

✓
After water fording, the SRS warning light came on with DTC B16EF. Inspection revealed poor sealing of the right rear fender liner, letting water seep into the sensor mounting hole and causing a short circuit that damaged the sensor internally. Replaced the right rear impact sensor, cleaned corrosion and water ingress on the harness connector, and renewed the waterproof seal using a rubber gasket. Fault resolved.
Original source ↗
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.