AU
B16E8

DTC B16E8 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance path (short to ground) between the Center Rear Impact Sensor (typically installed on the rear panel or C-pillar area) signal circuit and body ground — Atto 8

Safety System

DTC B16E8 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance path (short to ground) between the Center Rear Impact Sensor (typically installed on the rear panel or C-pillar area) signal circuit and body ground.

This sensor uses a piezoelectric or capacitive accelerometer.

During normal operation, it outputs a 0.5-4.5V analog voltage signal to the SRS control unit to reflect collision acceleration.

A short to ground causes the control unit to continuously receive a voltage signal near 0V, triggering the following: 1) The system determines the sensor has failed, enters fail-safe mode, and disables the associated airbags (including side curtain airbags and rear collision protection functions); 2) During an actual rear collision, the system cannot accurately identify collision severity, causing delayed or no airbag deployment; 3) If the short-circuit resistance is unstable, it triggers an intermittent fault, causing the SRS warning lamp to illuminate erratically.

This is a hard fault.

Upon detection, the control unit stores the DTC and illuminates the instrument cluster airbag warning lamp.

The B16E8 fault code on the Atto 8 indicates a high-severity SRS fault where the center rear impact sensor signal is shorted to ground. This can disable related airbags or affect rear collision detection. Common causes include damaged rear wiring insulation near the boot or C-pillar, or an internal sensor short. Have the vehicle inspected by an authorised dealer promptly. Typical repair cost data is available from recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Rear wiring harness mechanical damage: Long-term vibration, cargo friction, or a rear-end collision wears through the rear wiring harness insulation where it passes through the boot rear panel, C-pillar sheet metal holes, or retaining clips. The exposed copper conductor directly contacts the vehicle body metal, causing a short to ground.
  • 2Internal sensor circuit fault: Failure of the collision sensor internal signal conditioning circuit or piezoelectric element package seal causes insulation breakdown between the signal output terminal and the sensor metal housing (ground), forming an internal short circuit.
  • 3Water ingress or seal failure: Ageing boot seal, poor rear windscreen sealing, or water entering the rear wiring harness connectors (usually located on both sides of the rear panel) when wading, causing electrolytic corrosion between terminals or a short to earth.
  • 4Improper accident repair: During rear collision repairs, failure to route the wiring harness according to standard procedures allowed rear seat mounting bolts, interior trim panel clips, or metal edges to pinch the harness and damage the insulation.
  • 5Connector terminal corrosion: Long-term exposure to high-humidity environments (such as coastal areas or frequent vehicle washing) oxidizes the terminals of the rear sensor connector (usually a 2-3 pin waterproof plug). The resulting green copper corrosion creates a short-to-ground path or abnormally reduces resistance.
What To Do
  • 1
    Safety preparation: Switch the vehicle to OFF, disconnect the 12V low-voltage battery negative terminal, and wait at least 3 minutes (or as required by the repair manual, usually 5 minutes) to fully discharge the SRS backup power supply capacitor and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation and freeze frame analysis: Use VDS or a dedicated diagnostic tool to read the fault code status. Confirm B16E8 is a current fault (Current DTC), not a history fault. Record the vehicle status in the freeze frame data (vehicle speed, timestamp, etc.) and analyze the environmental conditions when the fault occurred.
  • 3
    Sensor location and visual inspection: Refer to the vehicle repair manual to determine the exact location of the center rear impact sensor (usually in the center of the rear panel for Yuan/Song MAX models, and the lower section of the C-pillar for Tang series). Remove the luggage compartment trim panel or C-pillar trim panel. Inspect the sensor for physical damage, signs of water ingress, or corrosion.
  • 4
    Wiring harness integrity check: Visually inspect the sensor wiring harness routing (typically along the rear panel crossmember or up the C-pillar to the SRS ECU). Specifically check for damaged rubber grommets where the harness passes through sheet metal holes, harness chafing against metal edges, and crushing or deformation caused by seat brackets or cargo.
  • 5
    Electrical measurement and fault isolation: Disconnect the sensor connector. Use a multimeter to measure the resistance between the harness-side signal pin (typically SIG or ACC) and body ground. Normal resistance is infinite (OL). If the resistance is less than 5Ω, a short to ground is confirmed. Next, disconnect the SRS ECU connector. Measure the circuit in sections to determine if the short is in the harness between the sensor and the ECU, or internal to the sensor.
  • 6
    Repair or replace: If the wiring harness has a short circuit, repair the damaged wire(s) (strip the insulation, solder, and apply double-layer heat-shrink tubing for waterproof insulation; replace the entire harness section if necessary). If the sensor has an internal short circuit, replace with a genuine collision sensor (Note: Sensors on some models are directional; ensure the arrow points toward the front of the vehicle during installation).
  • 7
    System Verification and Clearing: Reconnect all connectors and the battery. Use the diagnostic tool to clear the fault code. Perform the SRS system self-check cycle (typically requires turning the ignition switch to the ON position and waiting for the warning light to turn off). Confirm B16E8 does not return.
  • 8
    Function and road tests: Read the crash sensor data stream under static conditions and confirm the sensor output voltage is within the normal range (static value approximately 2.5V). Perform a road test to verify no intermittent faults occur when driving over rough roads and the SRS warning lamp remains off.
Real-World Cases
BYD DTC AI Analysis

SRS light on after driving through water: Aged boot seal caused water ingress into sensor

✓
2019 BYD Yuan EV. The owner reported that after driving through floodwater during heavy rain, the airbag warning light stayed on. Scanned with VDS and retrieved current fault code B16E8. Inspected the rear area and found the centre rear impact sensor mounted centrally on the rear bulkhead, with obvious water stains and green copper corrosion inside its connector. Further inspection revealed that the boot seal had aged and deformed, allowing rainwater to enter the rear bulkhead cavity via the tail light housings. Rectification: replaced the centre rear impact sensor assembly, cleaned the connector terminals and applied conductive anti-corrosion paste, replaced the boot seal, and cleared the rear bulkhead drain holes. Followed up for three months after repair with no recurrence.
BYD DTC AI Analysis

False alarm after rear-end collision repair: Rear seat bolt crushed wiring harness

✓
A 2021 BYD Tang developed an intermittent SRS warning light after repairs at an independent shop following a low-speed rear-end collision. Diagnosis found an intermittent B16E8 DTC. Removing the rear interior trim revealed that the repair shop had not secured the rear bulkhead harness in its channel according to OEM routing. Instead, the rear seat mounting bolts had pinched the harness, damaging the insulation and exposing the copper conductors to the vehicle body. The technicians rerouted the harness, repaired the damaged wires (soldered and applied double-layer heat shrink tubing), and adjusted the seat mounting bracket to prevent interference. After clearing the DTCs, they road tested the vehicle repeatedly and confirmed the fault was gone.
BYD DTC AI Analysis

New vehicle assembly defect: damaged wiring harness protective sleeve causing a short to ground

✓
One week after delivery, the airbag warning light came on in a brand-new 2020 BYD Qin petrol model. Scanning retrieved fault code B16E8-00 (current). Inspection found the rubber grommet on the middle/rear impact sensor wiring harness was not fully seated where it passes through the C-pillar sheet metal hole, leaving the harness in direct contact with the sharp metal edge. Driving vibrations cut through the insulation, causing a short to ground. Repair action: Repair the damaged wire, replace the harness rubber grommet, fit a protective rubber ring over the sheet metal hole edge, and ensure a safe clearance between the harness and metal edge. This is an assembly process issue—vehicles from the same production batch require inspection.
BYD DTC AI Analysis

Sensor internal component aging: seal failure from high-temperature environment

✓
A 2019 BYD Song MAX, four years old, driven in a hot climate its whole life, came in with the SRS warning light stuck on. The scan tool pulled DTC B16E8. We measured the sensor harness ground resistance: normal, open circuit. After reconnecting the sensor, the signal wire to ground showed only 12Ω—a clear internal short. Opening the sensor revealed the PCB potting compound had aged and cracked, allowing a capacitor lead to touch the metal housing. Repair: replaced the center rear impact sensor assembly (confirmed correct part number for the vehicle), cleared the fault codes, and ran a system calibration. Some variants also require a zero-point calibration with the diagnostic tool.
Other Atto 8 Fault Codes
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.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.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.