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B165511

B165511 is a BYD SRS (Supplemental Restraint System / airbag system) circuit diagnostic trouble code — Atto 3

Safety System

B165511 is a BYD SRS (Supplemental Restraint System / airbag system) circuit diagnostic trouble code.

B1655 specifically designates the Left Front Frontal Impact Sensor circuit, and 11 is the subtype code indicating a Short to Ground.

This fault indicates the SRS control module detects an abnormally low-resistance path (typically less than 1 ohm) between the left front impact sensor signal circuit and vehicle body ground, preventing the control module from correctly receiving the sensor acceleration signal.

This fault forces the airbag system into fail-safe mode and continuously illuminates the instrument panel SRS warning light.

During a collision, this condition may prevent the left front airbag from deploying normally or delay its deployment.

This constitutes a severe fault affecting occupant safety.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Incorrect wiring harness connection after accident repair (e.g., reversed pin positions or mismatched color markings causing the signal wire to short to ground)
  • 2A metal edge pinched or chafed the wiring harness inside the front bumper or left front fender, damaging the insulation and causing a short to ground.
  • 3Water ingress, corrosion, or deformed pins in the crash sensor connector causing a short circuit between the signal and ground terminals.
  • 4Left front crash sensor internal circuit fault (e.g., damaged piezoresistive element causing signal wire short to ground)
  • 5Failure to protect the wiring harness during front longitudinal beam repair or sheet metal work caused welding spatter or mounting screws to pierce the harness.
What To Do
  • 1
    Use a dedicated diagnostic tool (such as VDS or Launch X-431) to read fault codes and confirm B165511 is a current fault (Current DTC), not a history fault.
  • 2
    Turn off the ignition, wait at least 90 seconds to allow the SRS capacitor to discharge, then disconnect the left front crash sensor connector (usually located at the front of the left front longitudinal beam or the left side of the bumper).
  • 3
    Use a multimeter to measure the resistance between the signal pin on the vehicle harness side of the sensor connector and body ground. The normal value is infinity. A resistance of less than 1 ohm confirms a short to ground.
  • 4
    Visually inspect the left front wiring harness along its routing. Specifically check the harness inside the front bumper, inside the left front fender liner, and at the radiator support for damage, crushing, or wear.
  • 5
    Refer to the factory wiring diagram (such as the SRS section of the BYD E2/E3/Qin EV workshop manual). Measure the wiring harness continuity between the sensor and the SRS control module (usually under the centre console or floor), and verify the pin definitions (typically including the signal wire and low reference voltage wire).
  • 6
    Check the inside of the sensor connector for water stains, oxidation, or foreign matter. Clean with electrical contact cleaner or replace the damaged connector housing.
  • 7
    If the wiring harness is normal, replace the OEM left front frontal collision sensor (confirm the part number for the specific vehicle model; e.g., for the E2 model it is...). Install the sensor with the arrow pointing toward the front of the vehicle.
  • 8
    Reconnect all connectors, clear the fault code, and perform a system self-check: turn the ignition switch to the ON position and verify the instrument panel SRS warning light turns off after 6 seconds to confirm the fault is resolved.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Reversed wiring harness colours after accident repairs caused DTC B165511

✓
A BYD Song had the airbag warning light stay on after collision repairs. A diagnostic scan revealed DTCs B165511 (Left frontal collision sensor short to ground) and B167011 (Right side collision sensor short to ground). The technician initially replaced both collision sensors, but the fault persisted. Further inspection found that the engine bay wiring harness had been replaced during the accident repair. The work did not strictly follow the wiring diagram, causing the wire colours for pins 1 and 2 of the left frontal collision sensor connector B02(A) to be reversed compared to the diagram (the actual wire colours were opposite). After swapping the pin connections, the fault codes cleared. This case shows that during accident repairs, always verify pin definitions against the wiring diagram rather than relying solely on wire colour memory.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Left front impact sensor connector shorted due to water ingress after wading

✓
A BYD Qin EV's SRS warning light came on after the vehicle drove through water during heavy rain. A scan tool retrieved DTC B165511. Inspection found water inside the impact sensor connector beneath the left front bumper; the pins had green oxide, causing a short to ground on the signal wire. The waterproof seal on the connector had aged, letting water in when driving through water. Thoroughly cleaned the connector pins with electronic cleaner, applied conductive grease, replaced the waterproof seal with a new one, and wrapped the connector with waterproof tape. Cleared the DTC and the system returned to normal. Advised the owner to regularly check the sealing condition of the wiring harness connectors inside the front bumper.
BYD DTC AI AnalysisFrom Chinese market (translated)

Improper front bumper removal and refitting pinched and damaged the wiring harness.

✓
A BYD E2 had its front bumper replaced at a 4S dealership. After driving approximately 200 km, the airbag warning light illuminated. Retrieved DTC B165511. Inspection found that while installing the left front fender liner fixing screw, the technician trapped the left front impact sensor wiring harness under the screw. The screw threads pierced the harness insulation, allowing the copper core to contact the body metal and create a short to ground. Repair: Freed the trapped harness, wrapped the damaged area with electrical tape, rerouted the harness (ensuring at least 20 mm clearance from the fixing screw), added corrugated tubing for protection, and replaced the damaged harness section. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short circuit in aftermarket crash sensor

✓
A BYD E3 displayed an airbag fault immediately after the left front impact sensor was replaced with a non-genuine part following a minor collision. The retrieved fault code was B165511. Checking the harness side of the sensor connector revealed no short to ground, and harness resistance was normal. Suspecting the new sensor, the technician removed it and measured internal resistance. The signal terminal to the housing (ground) showed 0.5 ohms, confirming an internal short in the aftermarket sensor. Replacing it with a genuine impact sensor resolved the fault. Impact sensors are part of the safety system and require genuine parts. Aftermarket components may have internal circuit design defects.
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. Sources: [1]