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B169416

DTC B169416 indicates the airbag control unit (SRS ECU) detects an internal operating voltage below the calibrated threshold (typically below 9V), or a functional fault in the ECU internal power management module or voltage regulation circuit — Atto 3

Safety System

DTC B169416 indicates the airbag control unit (SRS ECU) detects an internal operating voltage below the calibrated threshold (typically below 9V), or a functional fault in the ECU internal power management module or voltage regulation circuit.

This hardware-level fault indicates the SRS ECU cannot maintain the stable operating voltage required for its internal microprocessor, acceleration sensor, and ignition circuit.

When triggered, the ECU enters fail-safe mode.

This condition can cause complete airbag system failure (airbags fail to deploy during a collision), prevent seat belt pretensioner activation, or generate a false alarm resulting in unintended airbag deployment.

This fault poses a severe safety risk and requires immediate repair.

4
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM airbag warning light suddenly illuminated while driving

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Vehicle: 2019 Qin Pro DM, 32,000 km. Symptom: While driving, the airbag warning light on the dashboard suddenly illuminated and stayed on. No accident history. Diagnosis: Scanned with VDS and retrieved current fault code B169416. Freeze frame data showed ECU voltage at 8.2 V. Measured battery voltage (normal). Inspected the SRS ECU connector and found slight oxidation on pin 1 (power supply); contact resistance measured 3.2 Ω. Fix: Cleaned pin 1 with electronic contact cleaner, applied conductive grease, and re-tightened the connector. Cleared the fault code. Followed up for one month—no recurrence.
BYD DTC AI Analysis

BYD E2 new car SRS system no communication

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Vehicle: 2020 BYD E2 EV, new vehicle PDI inspection. Symptom: Airbag warning light stays on, scan tool cannot communicate with SRS ECU. Diagnosis: Checked OBD pins 6 and 14 (CAN lines) — normal. No voltage at SRS ECU connector. Found loose SRS fuse slot in dashboard fuse box. Voltage intermittent when wiggling the fuse. Repair: Replaced fuse box base and tightened fuse pins. Fault resolved. Issue due to supplier assembly process.
BYD DTC AI Analysis

Qin EV showing SRS ECU fault after accident repair

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Vehicle details: 2019 Qin EV. Front collision, replaced front bumper and left front crash sensor. Symptom: After repairs, started the vehicle. Airbag light stays on. Read DTCs B169416 and B165C (front crash sensor fault). Diagnosis: Checked new sensor wiring – OK. The SRS ECU had recorded crash data and triggered its lockout protection. Standard unlock methods failed. Repair: Replaced SRS ECU (part number 5A-3638010C), performed online programming and sensor matching. Fault resolved.
BYD DTC AI Analysis

E3 SRS system low voltage fault after long-term parking

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Vehicle: 2020 E3. Started after sitting for 2 months. Symptoms: Hard starting, airbag warning light on, logged DTC B169416. Diagnosis: Battery voltage was only 10.5V. After charging, voltage returned to normal but the fault code persisted. Further inspection revealed aged capacitors inside the ECU; these could not maintain stable operating voltage after the high current surge during cold starting. Resolution: Replaced the SRS ECU and the battery. Advised the customer to disconnect the battery negative terminal for extended parking.
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.