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B169C00

DTC B169C00 indicates the airbag control unit (SRS ECU) detected a severe fault during its internal self-check — Atto 3

Safety System

DTC B169C00 indicates the airbag control unit (SRS ECU) detected a severe fault during its internal self-check.

This typically involves an ECU internal memory (EEPROM/Flash) data checksum failure, a main processor (MCU) calculation error, or an internal power supply/clock circuit fault.

This is a hard fault; the ECU cannot guarantee correct deployment of the airbags, seat belt pretensioners, and high-voltage interlock cut-off function during a collision.

Upon triggering, the SRS ECU enters fail-safe mode, illuminates the instrument cluster airbag warning light, and disables the entire airbag system.

Although the vehicle remains drivable, crash protection functions fail completely, posing a major safety risk.

4
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Following accident repairs, Qin EV SRS light stays on. DTC B169C00: internal fault.

✓
Following accident repairs on a 2019 Qin EV, the airbag warning light on the dash stayed on. VDS read DTC B169C00 (SRS ECU fault) and multiple historical crash codes. Inspection found the SRS ECU had no external damage, but the internal accelerometer had developed zero drift from the impact, so the ECU self-check flagged an internal fault. A software reflash did not clear the fault. Replaced the SRS ECU, reconfigured it, then performed output testing and static calibration. Fault resolved.
BYD DTC AI Analysis

E2 EV SRS system failed after flooding

✓
A 2020 E2’s airbag warning light came on after wading through floodwater. Diagnostics revealed active fault code B169C00. Removing and inspecting the SRS ECU (located beneath the centre console) showed mud traces on the connector and corrosion on the internal circuit board. Cleaning the connector and drying the ECU temporarily cleared the fault, but it returned after two days of driving. Replacing the SRS ECU and applying anti-corrosion treatment to the wiring harness permanently fixed the problem. For flood-damaged vehicles, replace the SRS ECU rather than just cleaning it.
BYD DTC AI Analysis

E3: Software bug causes intermittent airbag warning light while driving.

✓
The airbag warning light on a 2020 E3 came on intermittently while driving and went off after a restart. VDS scan showed stored fault code B169C00. Power, ground and CAN lines checked – no issues. ECU connector tight. A BYD TSB confirmed an early-version software defect that caused the ECU's internal watchdog to reset under certain electromagnetic conditions. Updated SRS ECU software to the latest version (V3.2.1 or higher). No recurrence during one month of monitoring.
BYD DTC AI Analysis

Qin EV triggered B169C00 after aftermarket stereo installation

✓
A 2019 Qin EV showed an SRS warning light the day after having aftermarket audio fitted at a non-authorised workshop. Diagnostics revealed DTCs B169C00 and U0151 (lost communication with SRS). Inspection found the workshop had broken the SRS ECU earth wire (G206) while prying off the centre console, causing an unstable ground for the ECU. Retightened the earth point, cleared the fault codes, and the system returned to normal. Tip: modifications involving SRS wiring easily cause such faults.
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.