AU
B16E700

DTC B16E700 indicates the airbag system (SRS) detects a communication interruption or physical disconnection of the Middle Rear Impact Sensor — Atto 3

Safety System

DTC B16E700 indicates the airbag system (SRS) detects a communication interruption or physical disconnection of the Middle Rear Impact Sensor.

This sensor, typically located on the inner rear bumper reinforcement or lower C-pillar, monitors rear-end collision acceleration.

A "not connected" status means the SRS control unit receives no valid signal from the sensor, typically indicating an open circuit or high-resistance condition.

The system determines the sensor circuit is open, the connector is detached, or the sensor has internal damage.

This fault causes the SRS to lose accurate rear-end collision monitoring capabilities.

It may force the airbag control unit into a degraded protection mode, disable specific airbag functions, or illuminate the airbag warning lamp continuously, severely compromising passive safety system reliability.

The B16E700 fault code on the Atto 3 indicates the SRS airbag system has lost communication with, or cannot detect, the middle rear impact sensor. Severity is medium because rear-end crash detection and some airbag functions may be reduced. Common causes include a loose or corroded rear bumper sensor connector, damaged wiring, or an internally failed sensor. The recommended fix is to visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Rear bumper wiring harness connector loose or disconnected: After driving on rough roads or through water, vibration can loosen the crash sensor plug inside the rear bumper, or poor sealing can cause pin corrosion and oxidation, resulting in poor contact.
  • 2Open circuit inside the sensor body: Physical impact to the center rear impact sensor (such as a minor rear-end or reversing collision) or long-term aging damages the internal piezoelectric element or circuit board, resulting in an open circuit.
  • 3Broken or worn wiring harness: As the harness routes from the main body harness to the rear bumper through the rear panel and floor trim strip, repeated bending or friction against other components breaks the copper wire, causing an open circuit fault.
  • 4Poor ground point: The sensor ground point (usually located on the rear floor or inside the C-pillar) is loose, oxidized, or covered with paint, creating excessive circuit resistance. This causes the SRS module to falsely detect a disconnected sensor.
  • 5SRS control unit connector issue: A loose control unit connector under the center console or in the front compartment causes poor contact at specific pins (corresponding to the center rear impact sensor signal wires).
What To Do
  • 1
    Fault Confirmation and Freeze Frame Analysis: Use VDS2000 or a dedicated BYD diagnostic tool to read fault codes. Confirm B16E700 is a current fault (Active). Record freeze frame data (ambient temperature and vehicle status). Check for accompanying SRS-related fault codes (e.g., B16E800 short to ground).
  • 2
    Visual inspection and connector check: Remove the rear bumper trim panel and locate the center rear impact sensor (usually in the middle or on the left side of the rear crash beam). Verify the sensor connector is fully seated. Check that the connector waterproof sealing ring is intact. Inspect the terminals for green corrosion, backed-out pins, or deformation.
  • 3
    Circuit continuity test: Disconnect the negative battery terminal. Disconnect the SRS ECU and sensor connectors. Use a multimeter to measure the continuity of the sensor wiring harness between the ECU and sensor ends. Normal resistance should be less than 1 Ω. Measure signal wire insulation to ground and power supply to confirm no short circuit.
  • 4
    Sensor body inspection: Measure the sensor body resistance with a multimeter (normal value is typically 500Ω-10kΩ; refer to the repair manual for exact specifications). An infinity (OL) reading indicates an internal open circuit. Lightly tap the sensor housing and observe if the resistance value fluctuates to confirm the condition of the piezoelectric element.
  • 5
    Ground point check: Check the sensor ground bolt on the left side of the rear floor (usually near the rear seat mounting point). Clean the contact surface and measure the ground resistance. Resistance must be less than 1Ω. If necessary, sand the surface and retighten the bolt.
  • 6
    Replacement Verification and System Reset: If the sensor is faulty, replace it with a genuine part (the part number must match the vehicle model, e.g., E2/Qin EV common part). Apply conductive grease during installation. Connect all connectors and reconnect the battery. Use the diagnostic tool to clear the fault code. Execute the 'SRS system self-check' procedure. Confirm B16E700 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Centre rear impact sensor communication fault after water wading

✓
A 2019 BYD Qin EV had the airbag warning light stay on after driving through floodwater in heavy rain. A diagnostic scan retrieved DTC B16E700. Technicians found water had reached the rear bumper level. After removing the rear bumper, they found obvious water stains inside the centre rear impact sensor connector – the pins were oxidised and black. Repair: cleaned the connector thoroughly with electronic contact cleaner, dried it, applied waterproof silicone grease, replaced the sensor (water-damaged internally), and wrapped the connector with waterproof tape. Once the fault was cleared, the technician advised the owner to check the rear bumper seal for deterioration.
BYD DTC AI Analysis

Sensor not plugged in after accident repair triggered a warning.

✓
After a minor rear-end collision, a BYD E2 had its rear bumper replaced at a third-party workshop. The owner then noticed the airbag warning light on the instrument panel and brought the vehicle to our shop. We found current fault code B16E700. Our inspection revealed the technician had not fully seated the center rear impact sensor harness connector during bumper installation. The connector lock did not click into place, and the plug eventually worked loose and disconnected due to vibration while driving. We reconnected the sensor plug and confirmed the locking tab engaged securely. We cleared the fault code using a diagnostic tool and ran an SRS cyclic test. This resolved the fault. We recommend standardizing the SRS self-check procedure after accident repairs.
BYD DTC AI Analysis

Wiring harness aging and breakage causing intermittent fault

✓
A 2020 BYD E3 had an intermittent airbag warning light while driving. The diagnostic tool flagged DTC B16E700. Connectors and sensor resistance were normal. Further inspection found the harness where it routes from the left C-pillar trim to the rear floor had been bent repeatedly by long-term boot opening and closing, partially breaking the internal copper strands and causing an intermittent open circuit. The fix: cut out the damaged section, spliced in same-spec wire (0.5mm² shielded twisted pair), soldered the joints, sealed with heat shrink tubing, and rerouted the harness away from sharp sheet metal edges. No faults returned during one week of post-repair monitoring.
BYD DTC AI Analysis

Internally damaged sensor body replacement case

✓
A 2019 BYD E2 lightly bumped into an obstacle while reversing. DTC B16E700 appeared right after. The sensor had no external damage, but its resistance was infinite — indicating the internal piezoelectric element cracked from the impact shock. The collision was very light, so the sensor likely had an inherent weakness or hidden prior damage. The technician replaced the sensor, cleared the fault codes, and ran the calibration procedure (activating the SRS ECU learning mode via the diagnostic tool) to set the correct collision threshold.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 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.