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B169100

DTC B169100 indicates the Supplemental Restraint System (SRS) is in "Factory Lock" mode — Atto 3

Safety System

DTC B169100 indicates the Supplemental Restraint System (SRS) is in "Factory Lock" mode.

BYD uses this protective locking mechanism during production, transport, or after SRS control module replacement.

This state forces the Airbag Control Unit (ACU) into factory test mode and electrically disables all airbags, side curtain airbags, and seat belt pretensioners.

These components will not deploy even in a severe collision.

This status is a software configuration issue, not a hardware fault.

It continuously illuminates the airbag warning light and completely disables the vehicle's passive safety functions.

Resolve this condition immediately.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Failure to complete the Pre-Delivery Inspection (PDI) procedure before new vehicle delivery, and failure to perform the "Exit Factory Mode" operation using the dedicated diagnostic tool.
  • 2Failure to perform online programming, coding configuration, or anti-theft matching after replacing the airbag control module (SRS ECU) causes the new module to default to a locked state.
  • 3Severe vehicle battery discharge, power interruption, or excessive voltage fluctuation causes SRS control module data loss or checksum failure, triggering a protective lockout.
  • 4Improper use of unauthorized diagnostic equipment, or accidental triggering of the factory mode activation command during servicing.
  • 5Abnormal anti-theft authentication communication between the SRS control module and the Body Control Module (BCM), or VIN matching failure causing module lockout.
What To Do
  • 1
    Connect the BYD VDS2000/3000 or ED400 diagnostic tool and enter the SRS airbag system to read fault codes. Confirm B169100 is the primary fault code and check for accompanying related fault codes such as B169200 (Factory Mode Active).
  • 2
    Check the vehicle repair history to confirm if the vehicle is new or has a recently replaced SRS module; measure the SRS control module power supply (constant B+, ignition IG1) and ground circuits to verify normal voltage (12V±0.5V).
  • 3
    Perform factory mode release: On the diagnostic tool, navigate to "SRS System" → "Special Functions" → "Factory Lock Release" or "Transport Mode Off". Follow the prompts to enter the 4-digit security code (usually, request this code through the BYD DTS system using the VIN).
  • 4
    If the special function fails to clear the fault, perform "Online Programming" or "Module Configuration". Flash the SRS control unit with the latest software and write the correct vehicle configuration parameters (airbag configuration, crash threshold, VIN).
  • 5
    After completing programming, clear all stored fault codes. Turn off the ignition and keep the power off for at least 60 seconds to allow the SRS capacitor to fully discharge and the module to enter sleep mode. Power the system back on to perform a system self-check and confirm the airbag warning lamp turns off normally after 6-8 seconds.
  • 6
    Perform functional verification: Use the diagnostic tool to read the data stream and confirm "System Status" changes from "Factory Mode" to "Normal"; perform a passive self-test (without deploying the airbag), confirm all circuit resistances are normal, and verify no current fault codes are present.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX wiper system communication fault

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Symptoms: The dashboard occasionally displayed a "Wiper System Fault" warning. The wipers operated abnormally in automatic mode and sometimes failed to return to the park position. A VDS scan revealed DTC B169100 (Front Wiper Motor Communication Fault or Signal Abnormality). Diagnosis: 1. Read fault code with VDS: B169100 – Front Wiper Motor Communication Signal Abnormal. 2. Checked the front wiper motor power supply circuit; supply voltage measured 12 V (normal). 3. Checked CAN bus communication; resistance on the CAN-H and CAN-L lines between the wiper motor and BCM read normal. 4. Disconnected the wiper motor connector and found internal oxidation and looseness. 5. Measured the wiper motor internal position sensor signal and found an intermittent open circuit. Repair: 1. Cleaned and tightened the wiper motor harness connector, then applied conductive paste to prevent oxidation. 2. Replaced the front wiper motor assembly (internal position sensor damaged). 3. Cleared fault codes and recalibrated the wiper position. 4. Test drove the vehicle and confirmed the fault was eliminated.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro wiper control module communication fault

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Symptoms: After starting the vehicle, the wipers auto-cycled once and the instrument panel displayed a wiper fault light. The owner reported that when driving in rain, the wiper speed could not be adjusted and remained stuck on high speed. The scan tool retrieved DTC B169100. Diagnosis: 1. Connected the VDS diagnostic system and retrieved Body Control Module (BCM) DTC B169100 (wiper motor control module communication fault). 2. Checked fuse F4/15 (wiper motor fuse) in the front compartment fuse box and found burn marks on the fuse holder. 3. Measured supply voltage to the wiper motor and found it fluctuating between 8–12V (unstable). 4. Inspected the harness between the BCM and wiper motor and found chafing inside the left front fender causing intermittent short circuits. 5. Stripped back the harness protection sleeve and found the CAN wire insulation damaged and contacting chassis ground. Resolution: 1. Repaired the damaged harness and re-wrapped it with insulating tape. 2. Replaced the burnt fuse holder. 3. Secured the harness with cable ties to prevent rubbing against the body. 4. Cleared DTCs and tested all wiper speeds — functions normal.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM wiper position sensor signal error

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Symptoms: After parking, the wipers failed to return to the rest position and stopped in the middle of the windscreen. The owner attempted a manual reset without success, and the wipers made abnormal noise when operated. Stored DTC B169100. Diagnosis: 1. Scanned with VDS: B169100 – wiper motor position feedback signal abnormal. 2. Checked wiper arm mounting and found the securing nut loose. 3. Removed the wiper motor and inspected the internal reduction gear and position sensor. 4. Found internal gear wear, preventing the position sensor from detecting the home position. 5. Checked BCM software version; found an early version with potential calibration issues. Resolution: 1. Replaced the front wiper motor assembly (including position sensor). 2. Reinstalled wiper arms and adjusted wiper blade positions. 3. Updated BCM control unit software to the latest version. 4. Performed wiper position learning procedure (accessed BCM special functions via VDS). 5. Tested wiper auto-return function: normal.
Original source ↗
BYD DTC AI Analysis

BYD Han EV wiper communication bus fault

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Symptoms: The instrument cluster displays "Check wiper system". The intelligent wiper function has failed (cannot automatically adjust based on rainfall). DTC B169100 is present and won't clear. Diagnosis: 1. Scanned all modules with a diagnostic tool; BCM stored DTC B169100 (wiper LIN bus communication fault). 2. The Han EV uses LIN bus communication (not CAN bus) for the wiper motor. 3. Measured LIN line voltage: 12V at rest (normal), no change during operation (abnormal). 4. Checked BCM LIN output and found an internal LIN driver chip failure in the BCM. 5. Disconnected wiper motor connector; measured 0Ω between motor-side LIN line and ground (internal short in motor). Repair: 1. Replaced front wiper motor (LIN communication module damaged). 2. Replaced BCM control unit as the LIN line had sustained damage. 3. Re-matched BCM to vehicle immobiliser system. 4. Configured wiper motor parameters and tested; intelligent wiper function returned to normal.
Original source ↗
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.