AU
B16A100

DTC B16A100 actually indicates an AVAS (Acoustic Vehicle Alerting System) fault, not an SRS airbag system fault — Atto 8

Safety System

DTC B16A100 actually indicates an AVAS (Acoustic Vehicle Alerting System) fault, not an SRS airbag system fault.

This DTC signifies the Pedestrian Warning Speaker has an open or short circuit, or the AVAS control module detects a speaker circuit fault.

AVAS is a mandatory safety feature on new energy vehicles that simulates engine sound to warn pedestrians at low speeds (0-20 km/h).

The system triggers this DTC when it detects abnormal speaker circuit resistance (normal range: 4-8 Ω), a wiring short to ground or open circuit, or an internal control module fault.

This disables the low-speed warning sound and compromises safety compliance.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Pedestrian warning speaker unit damaged: Internal coil burnt out causing a short circuit (resistance close to 0Ω) or coil open circuit (infinite resistance). Common causes include water ingress, aging, or quality defects.
  • 2Wiring harness connector fault: loose plug, terminal oxidation or corrosion, poor contact, or water ingress after wading causing an abnormal signal.
  • 3Wiring harness mechanical damage: Front compartment wiring harness chafes against sharp edges such as the fender liner and bumper bracket, causing insulation damage, intermittent short to ground, or open circuit.
  • 4AVAS control module fault: internal power amplifier damage, abnormal power supply (constant power +B, IGN power, or poor ground), or abnormal software calibration
  • 5Improper external modification or repair: Incorrectly modifying speaker wiring during non-professional audio modifications (e.g., mistakenly using the speaker negative wire as a ground wire), or incorrectly connecting the wiring harness during accident repairs.
What To Do
  • 1
    Use VDS2000 or an original BYD diagnostic tool to read the fault code. Confirm whether B16A100 is a current or history fault. Record the freeze frame data (vehicle speed, temperature, etc., at the time of occurrence).
  • 2
    Visually inspect the exterior of the pedestrian warning speaker (usually mounted on the front right side of the front compartment or inside the front bumper). Check the AVAS control module (usually located near the front compartment fuse box or inside the cabin dashboard) and all related connectors for signs of water ingress, corrosion, or looseness.
  • 3
    Disconnect the speaker connector and measure the speaker resistance with a multimeter. The normal value is 4-8Ω. An infinite reading indicates an open circuit, and a 0Ω reading indicates a short circuit.
  • 4
    Measure the AVAS control module power supply and ground: Check the voltage and continuity of the constant power (+B), ignition power (IGN), and ground circuits to ensure a normal power supply with no voltage drop.
  • 5
    Measure wiring harness continuity: Disconnect the AVAS module and speaker connectors. Measure the circuit continuity resistance between them (should be less than 1Ω), and measure the circuit insulation resistance to ground (should be greater than 10MΩ) to check for hidden open or short circuits.
  • 6
    Check the wiring harness routing: focus on harness securing points at the fender liner, front bumper bracket, engine compartment firewall, and other areas. Inspect for signs of chafing, pinching, or interference.
  • 7
    Repair or replace: If the wiring harness is damaged, wrap it with waterproof tape, install a protective sleeve, and adjust the routing to prevent interference; if the speaker is damaged, replace it with a genuine pedestrian warning speaker assembly (verify the part number matches).
  • 8
    System reset and matching: Clear the fault code. On some models, use a diagnostic tool to perform AVAS system self-learning or calibration to ensure the control module recognizes the new component parameters.
  • 9
    Function check: Perform a low-speed road test (0-20km/h) in a closed area. Confirm the vehicle emits a clear simulated engine alert sound when moving forward and reversing, no warning lights illuminate on the instrument cluster, and the fault code does not trigger again.
Real-World Cases
BYD DTC AI Analysis

BYD Han EV pedestrian warning speaker open circuit fault

✓
Symptoms: After starting the vehicle, the dash displayed "Please check pedestrian warning system". No alert sound during low-speed driving. Diagnosis: Used VDS2000 to read DTC B16A100. Measured the pedestrian warning speaker resistance as infinite (open circuit). Inspected the connector and found the plug loose with oxidised terminals. Solution: Cleaned the oxidised terminals and applied conductive paste. Reconnected and secured the connector. Cleared the fault code, and the system returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro DM Speaker Short Circuit Burnout Case

✓
Symptoms: Dashboard displayed "AVAS System Fault". No simulated engine sound at low speeds in EV mode. Diagnosis: Retrieved DTC B16A100. Live data showed speaker status "open circuit". Measured speaker resistance: 0 Ω (short to ground). Determined internal coil burnout. Solution: Replaced pedestrian warning speaker assembly (Part No. BYD-1102930-00). Performed AVAS system self-learning. Function returned to normal.
Original source ↗
BYD DTC AI Analysis

Wiring loom chafing caused an intermittent fault on BYD Yuan PLUS

✓
**Symptoms:** Intermittent B16A100 fault code after 5,000 km on new vehicle. Warning tone cuts in and out accompanied by static noise. **Diagnosis:** Stored faults indicated intermittent open circuit. AVAS module power supply tested normal. Found wiring harness with chafed insulation at inner fender liner, causing intermittent short to ground. **Solution:** Repaired damaged wiring and wrapped with waterproof tape. Adjusted routing and fitted protective sleeving. Cleared fault codes and road test confirmed normal operation.
Original source ↗
BYD DTC AI Analysis

BYD Dolphin speakers water-damaged after wading

✓
Symptom: After driving through water about 30 cm deep, the dash displayed a pedestrian warning system fault. DTC B16A100 could not be cleared. Diagnosis: Inspected the right-front speaker in the front compartment. Found water ingress marks on the housing, a corroded diaphragm edge, and unstable resistance measurements. Resolution: Replaced the water-damaged speaker. Checked the mounting point sealing and added an extra gasket. Advised against driving through water.
Original source ↗
BYD DTC AI Analysis

Aftermarket audio installation caused wiring fault in BYD Tang DM-i

✓
Symptoms: After an independent shop modified the audio system, a B16A100 fault code appeared. Diagnosis: We asked the shop and learned they had removed front compartment components. Inspection found the pedestrian warning speaker negative wire had been cut and incorrectly used as the audio ground, causing an AVAS module circuit fault. Solution: We restored the factory wiring harness connections, correctly reconnected the speaker negative wire to the AVAS module, repaired other modification damage, and the fault cleared.
Original source ↗
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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.