AU
B170511

This DTC indicates a short to body ground in the Left Curtain Shield Airbag ignition circuit — Atto 3

Safety System

This DTC indicates a short to body ground in the Left Curtain Shield Airbag ignition circuit.

In the BYD SRS (Supplemental Restraint System) architecture, B170511 constitutes a critical safety fault, indicating an abnormally low-resistance path (typically <1Ω) in the wiring from the Airbag Control Unit (ACU) to the left curtain airbag igniter.

The left curtain shield airbag mounts above the driver's side headliner, extending from the A-pillar to the C-pillar.

A short to ground results in the following: 1) The curtain airbag fails to deploy normally during a collision (ignition current diverts to the vehicle body); 2) The ACU continuously detects abnormal circuit resistance, illuminates the airbag warning light, and disables the entire SRS; 3) Unintended deployment occurs in extreme cases due to momentary circuit energization.

This fault involves a pyrotechnic device ignition circuit (trigger current approx. 1.5-2A, pulse voltage approx. 24-30V).

Strictly follow high-voltage safety procedures.

Disconnect the battery and wait for the capacitors to discharge before repairing.

The B170511 fault code on the Atto 3 indicates a high-severity short to body ground in the left curtain shield airbag ignition circuit. This can stop the curtain airbag deploying correctly and may disable the SRS, with the airbag warning light on. Common causes include damaged A/B/C-pillar airbag wiring or water ingress and corrosion at the connector. 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
  • 1Mechanical damage to the left A-pillar/B-pillar wiring harness: During removal and installation of the left A-pillar, B-pillar, or C-pillar interior trim panels, or during accident repairs, metal clips or sharp sheet metal edges cut the insulation of the curtain airbag wiring harness (wrapped in yellow corrugated conduit), causing the copper core to short to body ground. This is relatively common on Qin PRO series models.
  • 2Connector water ingress and oxidation: The sealing ring on the left curtain airbag connector (typically located at the base of the A-pillar or front of the headliner, part number GJ101/GJ102 series) degrades. After car washes or wading, the pins oxidize and form a conductive path, causing a short to ground.
  • 3Improper modification damage: When installing left A-pillar ambient lighting, routing dashcam wiring on the left side, or modifying the audio system, mounting screws or harness retaining clips pierce the dedicated SRS wiring harness, or the aftermarket harness compresses the factory curtain airbag harness, causing insulation damage.
  • 4Internal fault in the curtain airbag module: Damaged insulation between the left curtain airbag igniter internal bridge wire and the housing (typically accompanied by airbag deployment history, extreme high temperatures, or component aging) causes an internal short to ground.
  • 5Body ground circuit interference: Loose left body ground bolt (e.g., left instrument panel bracket ground point) causes arcing, burning through the adjacent SRS wiring harness insulation and causing a secondary short circuit.
What To Do
  • 1
    Safe power-down and wait: Turn off the ignition switch and disconnect the negative battery cable. Wait at least 3 minutes to ensure the ACU capacitor discharges completely. Wear an anti-static wrist strap. Do not use radio equipment in the repair area.
  • 2
    Fault status confirmation: Connect the VDS2000/VDS2100 diagnostic tool. Read DTC B170511 and freeze frame data. Distinguish between current (Current) and history (History) faults. Record environmental parameters such as vehicle speed and temperature at the time the fault occurred.
  • 3
    Initial visual inspection and disassembly: Remove the left A-pillar upper trim, left headliner trim, and sun visor. Inspect the curtain airbag wiring harness (yellow twisted pair) for obvious damage, crushing, burning, or contact with metal components. Pay special attention to the harness routing at the bottom of the A-pillar and the upper section of the B-pillar.
  • 4
    Resistance measurement for fault tracing: Disconnect the ACU connector (usually located under the center console or in front of the gear selector). Use a digital multimeter to measure the resistance between the left curtain airbag circuit (pins usually marked CUR_L+ / CUR_L- or A15/A16) and body ground. Normal resistance is >10 MΩ. A reading <1 Ω confirms a short to ground.
  • 5
    Segment isolation check: Disconnect the curtain airbag harness intermediate connector at the bottom of the left A-pillar or B-pillar. Measure the resistance to ground on the ACU side and the airbag side separately to pinpoint the short circuit location (wiring harness segment or airbag module segment).
  • 6
    Detailed wiring harness inspection: If the short circuit is in the wiring harness, inspect the harness outer covering along the left side of the dashboard, A-pillar, and headliner edge. Use a probe to gently lift the harness to check for hidden damage. Inspect the harness retaining clips for detachment causing harness movement and chafing.
  • 7
    Repair or replace: If the wiring harness has minor damage (<5mm), repair it by wrapping it with two layers of special high-temperature tape (Kapton tape). If the damage is severe or the harness is broken, replace the left curtain airbag wiring harness assembly. Do not splice the wires.
  • 8
    Connector handling: If water enters the connector, thoroughly clean the pins with electronic contact cleaner, apply conductive protective grease, and replace the sealing ring or the entire connector assembly. Verify the locking clip is intact.
  • 9
    System verification: After repair, reconnect all connectors and connect the battery. Use VDS to clear the fault code. Perform the 'SRS System Self-diagnosis' and 'Igniter Resistance Check' functions. Confirm the B170511 status changes to 'Passed'. Road test the vehicle over a bumpy road to confirm the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM left B-pillar wiring harness short to ground causing curtain airbag fault

✓
A 2019 Qin Pro DM presented with an intermittent airbag warning light while driving. VDS retrieved DTC B170511 (left side curtain airbag short to ground). Inspection revealed the vehicle had undergone a left A-pillar ambient light modification. Removing the left B-pillar trim panel revealed that a clip securing the aftermarket wiring harness had pierced the yellow corrugated tube of the original SRS harness, causing the curtain airbag igniter wiring to contact the B-pillar metal frame directly. Further inspection found the left-front ground point bolt in the engine compartment loose, creating an unstable ground return and exacerbating arcing at the chafed wiring. Repair: Removed the aftermarket wiring harness, repaired the damaged SRS harness insulation using special high-temperature tape, retightened the engine compartment ground point bolt to 10 N·m, rerouted the harness to maintain a 20 mm clearance from the bodywork, cleared the fault codes, and confirmed the SRS self-test passed.
Original source ↗
BYD DTC AI Analysis

Qin EV left B-pillar noise with curtain airbag wiring short circuit

✓
The owner of a 2019 Qin EV reported a creaking noise from the left B-pillar over rough roads, and the instrument cluster showed an airbag fault. Diagnosis found active DTC B170511. Removing the left B-pillar lower trim and seatbelt retractor revealed a separated weld in the three-layer sheet metal at the B-pillar—the outer panel was rubbing against the middle layer on uneven roads. Worse, metal burrs from the failed weld had pierced the left curtain airbag harness routed tight against the B-pillar, shorting the igniter wire to earth (measured resistance: 0.3 Ω). Repair: fixed the B-pillar sheet metal to eliminate the noise; replaced the left curtain airbag harness assembly (A-pillar to C-pillar section) and secured it with dedicated wiring clips; retorqued the seatbelt anchor to 45±5 N·m. Road test cleared the faults.
Original source ↗
BYD DTC AI Analysis

Qin PRO petrol left-side curtain airbag connector oxidised and shorted

✓
A 2018 Qin PRO petrol variant developed frequent airbag warning light illumination during the rainy season; DTC B170511 would not clear. Inspecting the left A-pillar lower side curtain airbag connector (GJ series) found the connector seal perished and missing, distinct green oxidation on the pins, and the locking tab fractured, letting the connector work loose. The curtain airbag igniter resistance measured normal at 2.3Ω, but the harness side showed only 0.6Ω to ground, confirming the short circuit occurred at the connector. Rainwater had tracked down the A-pillar trim and pooled inside the connector, causing the pins to short to ground. Replaced the left side curtain airbag harness connector (complete with seal), thoroughly cleaned the harness terminals using electronic cleaner, applied specialised conductive protective paste, and locked the connector securely. Also inspected and repaired the A-pillar trim weatherstrip leak. Fault resolved.
Original source ↗
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.