AU
B170E

DTC B170E indicates the SRS (Supplemental Restraint System) control unit detects a short to body ground in the right curtain shield airbag ignition circuit — Atto 3

Safety System

DTC B170E indicates the SRS (Supplemental Restraint System) control unit detects a short to body ground in the right curtain shield airbag ignition circuit.

Specifically, the ACU detects the resistance between the right curtain airbag deployment circuit (typically marked R CSA+ and R CSA-) and ground falls below the threshold (generally <2Ω).

Damaged wiring harness insulation, connector water ingress and corrosion, a shorted inflator inside the curtain airbag module, or a driver transistor breakdown inside the SRS control unit can cause this fault.

Under this fault condition, the circuit protection mechanism may disable the curtain airbag (preventing deployment).

In extreme cases, short-circuit current can trigger unintended deployment, posing a severe safety hazard.

The B170E fault code on the Atto 3 indicates a high-severity SRS fault where the right curtain shield airbag ignition circuit is shorted to body ground. This can disable the curtain airbag or, in rare cases, risk unintended deployment. Common causes include worn wiring around the right A-pillar or C-pillar, or water ingress causing connector corrosion. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Right A-pillar/C-pillar wiring harness wear: Long-term vehicle use or repeated interior trim removal and installation causes the right curtain airbag wiring harness insulation to wear through at sheet metal holes or retaining clips, resulting in direct contact between the copper conductor and the vehicle body metal.
  • 2Connector short circuit due to water ingress: A blocked sunroof drain hose or poor sealing allows rainwater to seep into the right roof side rail area, causing a short circuit between the curtain airbag wiring harness connector terminals (usually located above the B-pillar or near the C-pillar) or to ground.
  • 3Internal fault in the curtain airbag module: Manufacturing defects or aging cause insulation breakdown between the two terminals of the right curtain airbag assembly squib, resulting in a short to ground.
  • 4Internal damage to the SRS control unit: Power transistor or filter capacitor breakdown in the ACU internal drive circuit continuously grounds the curtain airbag control terminal.
  • 5Improper repair work: During accident repairs or interior modifications, excessively long fixing screws pierce the wiring harness, or incorrect harness routing causes chafing against the seat bracket or seatbelt mounting point.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, wait at least 3 minutes (to fully discharge the SRS capacitor), and wear an anti-static wrist strap.
  • 2
    Fault confirmation: Use VDS or the BYD dedicated diagnostic tool to read the DTC, confirm B170E is a current fault (Active DTC), and record freeze frame data.
  • 3
    Visual inspection: Remove the right A-pillar trim, headliner front edge, and C-pillar trim. Visually inspect the right curtain airbag wiring harness for obvious damage, burn marks, or liquid ingress.
  • 4
    Circuit measurement: Disconnect the right curtain airbag module connector (yellow waterproof plug). Use a multimeter to measure the resistance to ground at both harness-side terminals. Normal resistance is ∞ (open circuit). A reading <10Ω indicates a short circuit.
  • 5
    Section isolation: Disconnect the SRS control unit (ACU, usually located under the center console or behind the armrest) connector. Measure the resistance to ground at the wiring harness side of the curtain airbag circuit and at the ACU output terminal to determine if the short circuit is in the wiring harness or inside the control unit.
  • 6
    Wiring harness repair: If the short circuit is in the wiring harness section, carefully inspect the harness along the right roof rail. Focus on areas where the harness passes through sheet metal holes, retaining clips, and contacts the vehicle body metal. If damaged, repair the insulation with heat-shrink tubing or tape. Replace the wiring harness assembly if necessary.
  • 7
    Component replacement: If the wiring harness is normal but the resistance between the curtain airbag module terminals is close to 0 Ω, replace the right curtain airbag assembly; if the ACU output terminal shorts to ground, replace the SRS control unit (perform coding configuration simultaneously).
  • 8
    System verification: Reconnect all connectors, connect the battery, power on, and clear the fault code. Execute the 'SRS system self-check' or 'Configuration and Settings' procedure. Confirm B170E does not return and the instrument cluster airbag warning lamp turns off.
Real-World Cases
BYD DTC AI Analysis

Yuan EV SRS warning light illuminated after driving in rain

✓
After driving through heavy rain, a 2019 Yuan EV displayed an airbag warning light. The DTC read B170E (right side curtain airbag short to ground). Inspection found the right sunroof drain hose had detached, allowing rainwater to enter the A-pillar and corrode the terminals of the right side curtain airbag harness connector (located above the B-pillar), causing a short circuit. The repair: clean the corroded connector terminals, apply conductive protectant, and resecure the drain hose. Fault cleared.
BYD DTC AI Analysis

B170E fault after accident repair on Tang DM

✓
After a right-side collision repair on a 2021 Tang DM, the SRS light stayed on. Diagnosis found active fault code B170E. Inspection revealed that when the technician replaced the right A-pillar trim, a retaining screw was too long and pierced the right curtain airbag harness, causing a short to ground. Repair: Replaced the damaged harness section from ACU to the curtain airbag module, adjusted the screw length, and re-taped the harness. Fault cleared.
BYD DTC AI Analysis

Audio modification causes Song MAX fault

✓
2019 Song MAX. A tool pierced the SRS harness insulation while routing wires through the right A-pillar during roof speaker modification, causing the right curtain airbag circuit to short to the A-pillar metal frame and trigger DTC B170E. The SRS warning light came on immediately upon starting the vehicle the day after modification. Repaired the damaged harness (located in the headliner above the A-pillar) and rerouted the wiring to specification, keeping clear of the SRS harness path. Fault resolved.
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.