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 3

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.

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Mechanical damage to the rear wiring harness: Where the rear wiring harness passes through the luggage compartment rear panel, C-pillar sheet metal holes, or retaining clips, long-term vibration, cargo friction, or rear-end collisions wear through the insulation. The exposed copper core directly contacts the vehicle body metal, creating a short to ground.
  • 2Internal sensor circuit fault: Failure of the collision sensor's internal signal conditioning circuit or piezoelectric element package seal causes insulation breakdown between the signal output terminal and the sensor metal housing (ground), creating an internal short circuit.
  • 3Water ingress or seal failure: Aging boot seal, poor rear windscreen sealing, or water seeping into the rear wiring harness connectors (usually located on both sides of the rear panel) when driving through water, causing electrolytic corrosion between terminals or a short to ground.
  • 4Improper collision repair: During rear-end collision repairs, failing to route the wiring harness along the standard path caused rear seat mounting bolts, interior trim panel clips, or metal edges to pinch the harness, damaging the insulation.
  • 5Connector terminal corrosion: Prolonged exposure to high-humidity environments (such as coastal areas or frequent vehicle washing) causes the rear sensor connector (usually a 2-3 pin waterproof plug) terminals to oxidize. The resulting green corrosion creates a short-to-ground path or abnormally low resistance.
What To Do
  • 1
    Safety preparation: Switch the vehicle 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 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) rather than a history fault. Record the vehicle status from 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 confirm the exact location of the center rear impact sensor (Yuan/Song MAX models typically mount this in the center of the rear panel; Tang series models mount it at the lower C-pillar). Remove the luggage compartment trim panel or C-pillar trim panel. Inspect the sensor exterior for physical damage, signs of water ingress, or corrosion.
  • 4
    Wiring harness integrity check: Visually inspect the sensor wiring harness routing (usually 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 rubbing against metal edges, and harness 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 (usually SIG or ACC) and body ground. Normal resistance is infinity (OL). If the resistance is less than 5Ω, this confirms a short to ground. Next, disconnect the SRS ECU connector. Measure in sections to determine if the short is in the harness between the sensor and the ECU, or inside the sensor.
  • 6
    Repair or replace: If the wiring harness has a short circuit, repair the damaged wire (strip the insulation, solder the connection, and apply double-layer heat-shrink tubing for waterproof insulation; replace the entire wiring harness section if necessary). If the sensor has an internal short circuit, replace it with an OEM collision sensor (Note: Some models require specific sensor orientation; during installation, point the arrow toward the front of the vehicle).
  • 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 (usually requires turning the ignition switch to the ON position and waiting for the warning lamp to turn off after the self-check). Verify B16E8 does not recur.
  • 8
    Functional 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 of approximately 2.5V). Perform a road test to verify no intermittent faults occur when driving over bumpy roads and the SRS warning light 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 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.