AU
B16E8-00

This DTC indicates a short to ground in the signal circuit of the Supplemental Restraint System (SRS) Middle Rear Impact Sensor — Atto 3

Safety System

This DTC indicates a short to ground in the signal circuit of the Supplemental Restraint System (SRS) Middle Rear Impact Sensor.

The sensor mounts in the center of the rear bumper or rear longitudinal rail area.

Electrically, the insulation resistance between the sensor signal wire (typically a LIN communication or analog signal line) and body ground drops below the threshold (generally <1Ω).

This causes the SRS control unit (ACU) to continuously receive an abnormally low voltage signal.

This fault forces the SRS into fail-safe mode.

As a result, the system may fail to accurately detect rear impact acceleration, preventing the airbags, curtain airbags, or seat belt pretensioners from deploying in time during a rear-end collision.

Furthermore, the ACU may interpret the condition as a wiring fault and completely disable the rear impact monitoring function, illuminate the instrument panel SRS warning lamp, and downgrade the vehicle's passive safety system.

BYD Qin series models typically use a dual-axis accelerometer design for this sensor.

The ACU continuously registers a short to ground as 'abnormal circuit current' or 'signal voltage below lower limit'.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Damaged wiring harness sheathing in the rear bumper area allows direct wire contact with the metal body, causing a short to ground (common after reversing collision repairs or underbody scraping).
  • 2Center rear crash sensor body seal failure; internal water ingress or moisture causes the signal terminal to short to the sensor housing (ground).
  • 3Loose sensor connector (usually located inside the rear bumper or near the spare wheel well), or backed-out or corroded terminal pins, causing the signal pin to short to the connector housing ground.
  • 4Long-term vibration and friction wear the wiring harness insulation where it passes through body sheet metal holes or mounting brackets, causing contact with sharp metal edges.
  • 5SRS control unit (ACU) internal signal acquisition circuit fault causing a false short-to-ground detection (rule out by substitution).
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 3 minutes (or the time specified in the repair manual) to fully discharge the SRS energy storage capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use VDS or a dedicated diagnostic tool to read the complete SRS fault codes, record the freeze frame data, and confirm the fault is current (Present) rather than a history fault.
  • 3
    Locate the sensor: On BYD Qin models, the center rear crash sensor mounts to the inner middle section of the rear bumper reinforcement or below the spare wheel well. Remove the rear bumper inner liner for access.
  • 4
    Visual inspection: Check the sensor connector for looseness, signs of water ingress, and oxidized or bent pins; check the wiring harness sleeve for wear at the retaining clips and body panel holes.
  • 5
    Electrical measurement: Disconnect the sensor connector. Use a multimeter to measure the resistance between the harness-side signal wire and ground (Normal: ∞ or >10 kΩ). If continuity exists, trace the wiring backward. Measure the resistance between the sensor body signal terminal and the housing (Normal: 2-3 kΩ; close to 0 Ω if short-circuited).
  • 6
    Wiring harness repair: If the wiring harness is damaged, repair the insulation layer with heat-shrink tubing or waterproof tape. Replace the wiring harness assembly if necessary. Maintain sufficient clearance (>20mm) between the wiring harness and metal body components.
  • 7
    Component replacement: If the wiring harness is normal but the sensor has an internal short circuit, replace the rear center collision sensor (confirm the part number for the specific vehicle model; the Qin series typically uses the collision sensor assembly).
  • 8
    System verification: Reconnect all connectors and the battery, turn the ignition switch to ON, clear the fault code using the diagnostic tool, and perform the SRS system self-check. Verify DTC B16E8-00 does not return and the instrument cluster SRS warning light turns off.
Real-World Cases
BYD DTC AI Analysis

After water ingress, an internal short in the sensor caused the SRS light to stay on.

✓
A 2017 Qin EV300 illuminated the SRS warning light after driving through deep water in heavy rain. Stored fault code: B16E8-00 (middle rear impact sensor short to ground). No collision damage was found on the rear bumper, but water had entered the sensor connector upon removal. The sensor’s signal terminal to housing resistance measured 0.3 Ω, confirming an internal short from water ingress. Replaced the middle rear impact sensor and waterproofed the connector with conductive grease and a waterproof cover, clearing the fault. Cause: deteriorated sensor seal allowed water to seep in through the connector gap during wading.
BYD DTC AI Analysis

Wiring harness chafing after accident repair caused intermittent fault.

✓
A non-authorised workshop repaired this 2018 Qin EV450 following a minor rear-end collision. One month later, the SRS warning light began illuminating intermittently. Diagnosis revealed DTC B16E8-00 as an intermittent active fault. Inspection of the rear impact sensor wiring harness routing found that the previous repair had not secured the harness correctly. A metal edge at the spare wheel well mounting bracket had cut through the insulation, allowing the wire to intermittently contact the body ground when driving over bumps. Repaired the damaged harness section, re-routed the wiring to specification, and protected it with a rubber protective sleeve, which completely resolved the fault.
BYD DTC AI Analysis

Connector corrosion caused signal short to ground.

✓
After three years of use in a coastal area, a 2017 Qin 100 showed an SRS warning light, with DTC B16E8-00 stored. Inspection found severe oxidation on the pins of the rear impact sensor connector (located inside the rear bumper). Green copper corrosion formed a low-resistance path (measured 12Ω) between the signal pin and the connector housing (ground). Cleaned the connector pins and socket, applied electronic contact cleaner, and replaced terminals where necessary. After cleaning, resistance returned to normal (>2kΩ). Cleared the DTC and the system returned to normal. Advised the owner to periodically check the sealing condition of underbody wiring harness connectors.
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.