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B16A1-00

DTC B16A1-00 indicates the Airbag Control Unit (ACU) detected a communication anomaly or internal circuit fault in the Left Side Impact Sensor — Atto 8

Safety System

DTC B16A1-00 indicates the Airbag Control Unit (ACU) detected a communication anomaly or internal circuit fault in the Left Side Impact Sensor.

The SRS_ECU continuously monitors the supply voltage, signal circuit resistance, and LIN/CAN communication frame rate of each impact sensor.

The ECU sets this DTC if it detects an open circuit, short to ground, or short to power in the left sensor wiring, or a sensor data validation error (e.g., capacitance drift, acceleration signal out of range) lasting over 200ms.

Once set, the system enters a degraded mode.

This mode may disable the left side airbag and curtain airbag deployment, or on certain models, restrict the entire airbag system, posing a severe safety hazard.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Loose left B-pillar sensor connector on Qin EV450 causing intermittent fault

✓
A 2018 Qin EV450 with 32,000 km on the clock occasionally displayed "Check SRS System" on the dashboard; the warning cleared after cycling the ignition. Used VDS to retrieve DTC B16A1-00 (intermittent). Inspected the side impact sensor inside the left B-pillar interior trim and found the connector locking tab had broken, allowing the plug to work loose and causing an intermittent connection when driving over bumps. Replaced the sensor wiring harness connector using a wiring repair kit, re-secured the harness routing, and cleared the fault.
BYD DTC AI Analysis

Qin 100 left impact sensor internal circuit damaged

✓
2017 Qin 100. Airbag warning light stayed on. DTC B16A1-00 (current fault) stored. Sensor power supply measured 5.02V (normal), but sensor signal output voltage was 0.3V (abnormal). Replaced left side impact sensor (part number: K9-5820600). The DTC changed to historical; after clearing it did not reappear. Cause: damaged accelerometer chip inside the sensor.
BYD DTC AI Analysis

Sensors not calibrated after accident repair on Qin EV300

✓
2017 Qin EV300. After a minor left-side collision, an outside shop replaced the left front door and B-pillar outer panel, then the airbag light came on. Diagnostics showed B16A1-00 with B1650-00 (crash data stored). Inspection revealed the shop had reinstalled the left impact sensor but under-torqued the mounting bolts, causing the sensor angle to shift. Re-torqued the bolts to 8 N·m, then used VDS to run impact sensor zero-point calibration and crash data clear. Fault resolved.
BYD DTC AI Analysis

Wiring harness chafing caused a short to earth.

✓
The airbag warning light on a BYD Qin 80 suddenly illuminated while driving. Inspection found the wiring harness protective sleeve near the left front seat rail damaged. The side impact sensor signal wire had chafed against the seat mounting bracket, causing an intermittent short to earth. Repaired the wire by soldering and insulating with heat-shrink tubing, rerouted the harness to avoid the seat slide travel, and replaced the damaged corrugated tubing. Fault resolved.
BYD DTC AI Analysis

SRS ECU software fault causing false alarms

✓
2017 BYD Qin 100. No obvious collision history, but DTC B16A1-00 kept recurring. Replaced the sensor and wiring harness, yet the fault persisted. Checked ACU software version: V1.2. Consulted BYD TSB and found that version has a false-positive defect. Upgraded ACU software to V1.5 and performed sensor configuration matching. The fault has not returned.
Other Atto 8 Fault Codes
B1108For 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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
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.