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B169800

DTC B169800 indicates an internal fault or communication failure in the airbag control unit (SRS ECU) — Atto 3

Safety System

DTC B169800 indicates an internal fault or communication failure in the airbag control unit (SRS ECU).

As the core control module of the airbag system, the SRS ECU monitors crash sensor signals, processes crash algorithms, and controls airbag and seat belt pretensioner deployment.

This DTC indicates the ECU self-check detected an internal processor fault, memory error, power supply fault, or CAN communication interruption with other modules (such as the Vehicle Control Unit or Body Control Module).

This fault poses a severe safety risk and may cause the airbags to fail to deploy or to deploy inadvertently during a collision.

Repair immediately.

4
Cases Logged
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro EV: SRS warning light came on while driving, logged DTC B169800

✓
The SRS warning light on the dashboard suddenly came on while driving normally. Connected a VDS diagnostic tool and read current fault code B169800 (SRS ECU fault) and stored fault U0155 (lost communication with instrument cluster). Inspection revealed the vehicle had recently had an aftermarket audio system installed, and the centre console had been removed and reinstalled. Removed and inspected the SRS ECU, located under the centre console on the central tunnel, and found the ECU power connector not fully seated, causing intermittent power loss from vibration while driving. Reseated the connector and secured the wiring harness. Cleared the fault codes; the SRS light went out. Road tested for 50 km with no recurrence of the fault.
Original source ↗
BYD DTC AI Analysis

BYD Han EV reports DTC B169800 after accident repair; code will not clear.

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Front-end collision. Replaced front bumper and impact sensors. After repairs, airbag warning light stayed on. Read DTC B169800. Inspection found slight deformation of the SRS ECU housing, no cracks. Measured ECU power supply and ground: normal. CAN communication: normal. ECU internal self-test failed. Determined shock wave from collision damaged internal accelerometer or processor in SRS ECU. Replaced with new SRS ECU. Performed online programming via VDS, wrote VIN and configuration parameters. Ran system self-test: passed. Fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD e2 intermittently reports SRS ECU fault

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The owner reported the SRS warning light occasionally comes on, sometimes clearing after cycling the ignition. The diagnostic scanner retrieved intermittent DTC B169800. Inspection found the vehicle had been through water, with water accumulation marks at the SRS ECU mounting bracket beneath the floor. Removed the ECU and found slight oxidation inside the connector. Cleaned the ECU and harness connectors, dried internal moisture with compressed air, and applied electrical contact protectant. Also found the ECU ground wire attachment point rusted; sanded the ground terminal and retightened. Followed up for one month post-repair, no recurrence.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM sets DTC B169800 after battery pack replacement

✓
After replacing the power battery pack at the dealership, the airbag warning light illuminated during handover. Retrieved DTC B169800. Investigation found the 12V battery had been disconnected for too long during the repair, and the technician had disconnected the SRS ECU connector to gain access. A communication timeout occurred after reconnection. Performed SRS reconfiguration and calibration using VDS, cleared the DTC, and the system returned to normal. Root cause: ECU data loss after power disconnection, requiring system reconfiguration.
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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.