AU
B167B11

DTC B167B11 has different definitions depending on the vehicle model — Atto 8

Safety System

DTC B167B11 has different definitions depending on the vehicle model.

Early models, such as the BYD E2, E3, and Qin EV, define this fault as a short to ground in the right rear side impact sensor (SIS) signal circuit within the SRS airbag system.

Newer models, such as the Han EV, define it as a short to ground in the left front seat heater circuit.

Regardless of the application, sub-code '11' indicates a short to ground.

For the SRS system, this fault indicates the airbag control unit (ACU) continuously detects 0V on the right rear side impact sensor signal wire (below the 0.3V threshold), preventing the ACU from receiving the correct collision acceleration signal.

This triggers the SRS fail-safe mode, constituting a serious safety hazard.

The fault may prevent the side airbag or side curtain from deploying correctly during a side impact, or falsely trigger the airbag warning lamp while driving.

For the seat heater definition, this fault indicates the heating element circuit current increased abnormally, causing the control module to activate overcurrent protection.

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Cases Logged
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Causes
Likely Causes — Atto 8
  • 1Right rear side impact sensor harness insulation wears through and contacts the body sheet metal or seat frame, causing a short to ground (common due to improper harness securing after rear fender liner removal and installation).
  • 2Water ingress and corrosion in the sensor connector causing the signal pin to short to ground (common after vehicle wading, car wash fluid residue, or an aging seal ring)
  • 3Crash sensor internal electronic component failure causes the signal wire to short to ground (internal capacitor breakdown or IC damage).
  • 4During rear seat or C-pillar trim panel removal or installation, the seat slide rail, retaining screws, or clips pinched and damaged the wiring harness.
  • 5During accident repairs in the rear fender area, a sheet metal edge cut the wiring harness or insulation at a mounting point sustained damage, causing a short to body ground.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 90 seconds (to ensure the SRS system capacitors fully discharge) to prevent accidental airbag deployment. Wear an anti-static wrist strap.
  • 2
    Locate the sensor: Remove the right rear C-pillar trim panel and rear fender liner, then locate the right rear side impact sensor (usually above the rear sill beam, at the lower C-pillar, or behind the rear seat backrest).
  • 3
    Visual inspection: Check the sensor connector for looseness, water ingress, and corroded or bent pins. Check the wiring harness corrugated conduit for wear, damaged insulation, and crush marks.
  • 4
    Circuit measurement: Measure the resistance to ground of the sensor signal wire (typically the ACU-supplied 5V reference voltage circuit) using a multimeter. The standard value must be greater than 10MΩ. A reading close to 0Ω confirms a short to ground.
  • 5
    Sectional troubleshooting: Disconnect the sensor connector. Measure the resistance to ground on the wiring harness side (from the ACU) and the sensor side separately to determine if the short circuit is in the wiring harness or internal to the sensor.
  • 6
    Wiring harness repair: If the wiring harness is damaged, cut out the damaged section, re-solder the wires or crimp new terminals, apply dual-wall heat-shrink tubing (adhesive-lined inner layer) for waterproof insulation, and re-secure the wiring harness to prevent interference.
  • 7
    Component replacement: If the sensor has an internal short circuit, replace the right rear side impact sensor (Note: Use genuine parts. Typical installation torque is 8-10 N·m. Do not overtighten to prevent housing damage).
  • 8
    System verification: Restore connections, turn on the power, use the VDS diagnostic tool to clear the fault codes, and perform the SRS system self-check (requires static and dynamic road test verification). Confirm the fault code does not reappear and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX left front heated seat failure (similar fault code B16A311)

✓
Symptoms: Dashboard displayed 'Seat system fault'. Left front seat heating failed; pressing the heater switch caused the indicator to flash for 3 seconds, then extinguish. Diagnosis: Scanned with VDS and retrieved B16A311 (Left front seat heater circuit short to earth). Measured heating pad resistance at 0.5 Ω (specification 2-5 Ω). Found the seat rail pinching the wiring harness, causing the heater element to short to earth. Fix: Replaced the left front seat heating pad assembly (S6J-6807100). Repaired and rerouted the wiring harness. Adjusted the seat rail stops.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro DM Seat Control Module Communication Fault (DTC B167111/B167B11)

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Symptoms: Instrument cluster intermittently displayed "Please check seat system", driver's electric seat adjustment occasionally failed, and seat memory positions were lost. The fault appeared easily on rough roads. Diagnosis: Read DTC B167111 (seat control module communication fault) and historical code B167B11. Measured CAN-H voltage to ground: 0.3V (standard 2.5-3.5V). Found the wiring harness retaining clip under the seat had detached; the harness rubbed against the seat rail and wore through, causing the CAN-H wire and heater power wire to short to ground simultaneously. Fix: Repaired the CAN-H and heater power wires, applied heat shrink tubing for waterproofing, replaced the wiring harness retaining clip, and recalibrated the seat memory positions.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM front seat heating automatically turns off (DTC B168311)

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Symptoms: Heated seats switch off automatically after 3–5 minutes. The instrument cluster displays 'Seat Heating System Fault' and both front heated seats are inoperative. The vehicle had previously been driven through water. Diagnosis: Retrieved DTC B168311 (Right Front Seat Heater Circuit Short to Ground) and historical code B167B11. Inspected the seat heating control module (located beneath the right front seat) and found water staining and corrosion. Measured the resistance of the right front heating pad to ground at 0.2 Ω (short circuit); the left front reading was normal. Resolution: Replaced the right front seat heating pad and control module. Removed the seat, cleared accumulated water from the seat frame, and applied rust inhibitor. Checked the floor wiring harness for water exposure.
Original source ↗
BYD DTC AI Analysis

BYD Han EV heated seat low setting inoperative (DTC B167B11/B167C11)

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Symptoms: Left front seat heater only operates on the high setting; selecting low automatically reverts to off, with the climate panel displaying "Seat Fault". Diagnosis: Retrieved DTCs B167B11 (Left Front Seat Heater Circuit Short to Ground) and B167C11. Measured the low-setting heating element shorted to ground at 0.1 ohms; the high setting measured normal. Disassembly found the heating pad delaminated and aged, with the low-setting heating wire shifted and contacting the seat metal frame. The retention tape also deteriorated and detached from heat exposure. Resolution: Replaced the left front seat heating pad with an upgraded unit featuring optimised heating element retention, fitted a mica heat shield, and flashed the seat control module to software version 2023V03.
Original source ↗
Other Atto 8 Fault Codes
B1108For 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.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.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.
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.