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B169D-00

DTC B169D-00 indicates the airbag control unit (SRS ECU) detects an internal fault or abnormal system communication — Atto 3

Safety System

DTC B169D-00 indicates the airbag control unit (SRS ECU) detects an internal fault or abnormal system communication.

This ECU is the core control module of the airbag system.

It monitors crash sensor signals, determines crash severity, controls the deployment timing of the airbags and pretensioners, and records crash data (EDR).

Faults in the ECU internal processor, memory, or power management circuit, interrupted communication with the vehicle CAN network, or data checksum errors trigger this fault code.

This fault may cause the airbag system to enter fail-safe mode, preventing normal airbag deployment during a collision and severely compromising occupant passive safety protection.

This is a critical safety-related fault.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Qin EV300 intermittent SRS ECU fault after water wading

✓
A 2017 Qin EV300 presented with an intermittent 'Check SRS System' warning on the instrument cluster, along with intermittent DTC B169D-00. Investigation revealed the vehicle had been driven through flood water. The SRS ECU is located beneath the centre tunnel; upon disassembly, water staining was found inside the ECU connector and minor oxidation on the pins. Cleaning the connector and applying conductive paste temporarily cleared the fault, but it returned after one week. Measurement identified corrosion on the ECU ground wiring harness following water ingress, causing contact resistance to increase to 15Ω. Replacing the ground wiring harness and resealing the connector permanently resolved the fault.
BYD DTC AI Analysis

Qin 100 B169D-00 fault after accident repair

✓
After front collision repairs on a 2017 Qin 100, the airbag warning light stayed on, storing DTC B169D-00. Inspection found the front impact sensor wiring harness had been damaged in the crash. The repair shop used a non-genuine harness, causing CAN bus signal interference. The SRS ECU detected the communication fault and triggered a protective fault. Replaced the front impact sensor harness with a genuine part, confirmed no noise on the CAN bus waveform, cleared the DTCs, and the system returned to normal.
BYD DTC AI Analysis

Qin EV450 software version defect causes false positive

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A 2018 BYD Qin EV450 developed a B169D-00 fault code after a service. The vehicle had no collision history, and a wiring inspection found no abnormalities. Using a VDS diagnostic tool, technicians found the ECU was running an early software version (V1.02) with a known self-check logic defect. They upgraded the ECU software to V1.05, which cleared the fault code automatically. The fault has not returned. This software issue is common in some 2018 production batches. Resolve it via an OTA update or a dealer visit for the software upgrade.
BYD DTC AI Analysis

Battery discharge caused abnormal SRS ECU voltage

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A long-parked Qin 80 had a severely discharged battery (voltage <9V). After a jump start, multiple warning lights illuminated on the dashboard, including the airbag light. The scan tool retrieved DTC B169D-00. The ECU self-check had failed due to the low voltage. We fully charged the battery (voltage restored to 12.8V) and cleared the codes; the fault did not return. We recommended the owner check the battery State of Health (SOH) to prevent false ECU faults from voltage instability.
BYD DTC AI Analysis

ECU incompatibility fault after aftermarket airbag replacement

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A workshop replaced the driver airbag on a Qin EV300 with an aftermarket unit. Afterwards, the instrument cluster airbag warning light came on and the system stored DTC B169D-00 along with multiple airbag circuit faults. The shop found the aftermarket igniter resistance was 1.2 Ω, while the OEM specification is 2.0 Ω ± 0.3 Ω, causing the ECU to detect a system fault and activate protection mode. After installing a genuine driver airbag, the technician used a scan tool to run the 'replace airbag component' reset procedure. The fault codes cleared and the system returned to normal operation.
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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.