AU
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 — Seal 6 EV

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.

The B16A1-00 fault code on the Seal 6 EV indicates a communication or circuit fault in the Left Side Impact Sensor, detected by the Airbag Control Unit. This medium-severity issue typically stems from a damaged sensor accelerometer or corroded wiring connectors, potentially disabling the left side or curtain airbags. As five real cases have been recorded, typical repair cost data is available. Visit an authorised dealer for diagnosis and repair.
5
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1A damaged internal accelerometer or aged capacitor in the left side impact sensor (located inside the left B-pillar trim panel) causes abnormal signal output.
  • 2Wiring harness connector between the SRS ECU and the left-side impact sensor (usually located under the left front seat or at the base of the B-pillar) is loose, has water ingress and oxidation, backed-out pins, or poor contact.
  • 3Airbag Control Unit (ACU) internal memory failure, power supply chip fault, or software logic error causing a false sensor fault.
  • 4Following a left-side collision, loose sensor mounting or internal micro-cracks cause an intermittent open circuit, but the sensor does not meet replacement criteria.
  • 5Low 12V battery voltage or excessive voltage drop in the SRS system power supply circuit prevents the ECU from correctly identifying the sensor during initialization.
What To Do
  • 1
    Connect the VDS2000 or BYD dedicated diagnostic tool. Enter the SRS system to read the complete DTCs. Confirm whether B16A1-00 is a current fault (Active) or a history fault (History). Record the vehicle speed and sensor voltage values from the freeze frame data.
  • 2
    Disconnect the 12V battery negative terminal and wait 90 seconds for the capacitor to discharge. Remove the left B-pillar lower trim panel. Verify the side impact sensor connector (black plug, 2-pin or 3-pin) is securely locked. Inspect the pins for oxidation or recession. Apply conductive grease if necessary.
  • 3
    Use a multimeter to measure the voltage at the sensor wiring harness connector. With the ignition switch ON, the power supply pin voltage should be 4.8-5.2V and the signal pin voltage should be 2.3-2.7V. Measure the sensor resistance. The normal range is 1.8-3.2kΩ. Replace the sensor if the deviation exceeds ±10%.
  • 4
    Check wiring harness continuity: Perform a continuity test on the wiring harness between the ACU (usually located under the center tunnel) and the left sensor. Confirm no open circuits and insulation resistance >1MΩ. Specifically inspect the wiring harness near the seat rail for wear.
  • 5
    If the wiring harness and sensor are normal, update the SRS ECU software to the latest version (if available) or perform the 'Sensor Configuration' and 'Crash Record Clear' functions. Replace and recode the ACU control unit if necessary.
  • 6
    Reconnect all components, restore power, clear the fault code, and perform a system self-check (wait for the indicator light self-check to complete). Perform a road test (including bumpy roads and cornering) to confirm the fault code does not recur and the airbag warning light turns off.
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 Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV overview →
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.