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B16C7

DTC B16C7 indicates the airbag control unit (SRS ECU/ACU) detected an internal system fault — Atto 3

Safety System

DTC B16C7 indicates the airbag control unit (SRS ECU/ACU) detected an internal system fault.

This typically points to an abnormality in the ECU internal microprocessor, non-volatile memory (NVM), power supply monitoring circuit, or safety relay drive circuit.

As a hard or persistent fault, it can force the airbag system into fail-safe mode and disable airbag deployment.

On BYD e-platform and DM models, a gateway communication interruption may accompany this fault, affecting the normal drive logic of the instrument cluster airbag warning lamp.

This Safety Level 2 fault requires immediate repair.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Tang DM airbag warning light illuminated while driving with fault code B16C7.

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2021 Tang DM. Airbag warning light illuminated intermittently while driving. Scan tool showed DTC B16C7. Inspection found loose battery terminals causing voltage to drop below 9V during starting, triggering the SRS ECU low-voltage protection. Tightened the terminals and replaced the aged battery. Cleared the fault codes. Fault resolved.
BYD DTC AI Analysis

Song MAX SRS system inoperative after water ingress

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2019 BYD Song MAX. After driving through water, the airbag warning light stayed on with DTCs B16C7 and U0155 (lost communication with SRS). Found water entry in the cabin floor wiring harness connector, causing degraded insulation between CAN-H and CAN-L. Cleaned and dried the harness, replaced the SRS ECU (damaged by voltage surge), re-matched the system, and restored normal operation.
BYD DTC AI Analysis

Yuan EV reports DTC B16C7 after dashboard replacement.

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2019 BYD Yuan EV. After accident repairs replaced the instrument panel assembly, the airbag light stayed on. Diagnosis found the battery remained connected during the work, and plugging/unplugging the SRS ECU connector caused a surge current that damaged the ECU's internal power management module. Replaced the SRS ECU with a new one and performed online configuration to resolve the problem.
BYD DTC AI Analysis

Interrupted software flash caused B16C7 on Qin Pro DM

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The Qin Pro DM lost power unexpectedly during an SRS system update at the dealership. After restarting, it set code B16C7 which could not be cleared. Inspection found corrupted ECU internal calibration data. Using a dedicated diagnostic scanner, the technician reflashed the latest SRS software and performed the full calibration procedure (including impact sensor zero-point calibration), fixing the fault.
BYD DTC AI Analysis

Sensor short circuit triggered ECU protection on Song Plus DM-i

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2022 Song Plus DM-i. Left front impact sensor harness inside the fender damaged, shorting to ground and causing the SRS ECU to enter protection mode, logging DTC B16C7. Repaired the harness insulation, replaced the damaged impact sensor. Cleared fault codes — system self-test passed, airbag warning light off.
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.