AU
B16AE

DTC B16AE indicates the Supplemental Restraint System (SRS) detects a squib encryption verification failure or abnormal encrypted communication in the ignition circuit — Qin Plus

Safety System

DTC B16AE indicates the Supplemental Restraint System (SRS) detects a squib encryption verification failure or abnormal encrypted communication in the ignition circuit.

In BYD vehicles, the airbag ECU uses an encrypted communication mechanism (Ignition Encryption Protocol) with each airbag module and seat belt pretensioner to prevent accidental deployment or malicious interference.

The SRS ECU stores this fault code when it cannot verify the squib identity encryption key, or when it detects ignition circuit resistance outside the standard range (typically 2.0-3.0Ω) accompanied by an abnormal encryption signal.

This fault may prevent the corresponding airbag from deploying normally during a collision, or trigger the system to enter fail-safe mode (disabling some airbag functions).

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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Airbag ECU internal software error or encryption chip fault prevents correct verification of the igniter identity.
  • 2Airbag squib (driver/passenger/side airbag) wiring harness connector oxidized, loose, or has excessive contact resistance, disrupting encrypted signal transmission.
  • 3Installing a non-OEM airbag assembly or failing to perform encryption matching after accident repairs results in an encryption key mismatch between the old and new components.
  • 4Abnormal SRS ECU power supply (voltage below 9V or above 16V) causing an encryption algorithm calculation error
  • 5Water ingress into the airbag wiring harness connector from vehicle wading or high-humidity environments, causing an ignition circuit short or encrypted communication interference.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 3 minutes for the SRS ECU capacitor to fully discharge to prevent accidental airbag deployment.
  • 2
    Diagnostic tool check: Use the VDS2000/BYD dedicated diagnostic tool to read the complete fault code, verify it is B16AE-00, and record the voltage value and igniter position from the freeze frame data.
  • 3
    Basic circuit inspection: Check the power and ground wiring harnesses of the SRS ECU (usually located under the center console or inside the armrest box); inspect each airbag connector (yellow plug) for oxidation or looseness, and measure the squib resistance (standard: 2.0 ± 0.3 Ω).
  • 4
    Encryption verification test: Use the diagnostic tool to execute the 'SRS System Self-test' and 'Igniter Encryption Matching' functions to check the encrypted communication status of each igniter. If encryption fails at a specific location (e.g., driver airbag), check the clock spring or wiring harness at that location.
  • 5
    Software procedure: If the wiring is normal, update the SRS ECU software (if a newer version is available) or perform an 'encryption key reset/re-matching' operation.
  • 6
    Component replacement: If the airbag control unit has an internal fault, replace it with an OEM SRS ECU and perform coding and matching. If a specific airbag module is faulty, replace the module and use the diagnostic tool to perform 'component encryption learning'.
  • 7
    System verification: Clear the fault code, reconnect the battery, start the vehicle, and observe if the airbag warning light turns off. Perform a crash sensor simulation test (using the diagnostic tool function, not physical impact) to verify system function.
Real-World Cases
BYD DTC AI Analysis

2021 BYD Tang driver airbag encryption verification failed

✓
After accident repairs, the dashboard showed 'Airbag Fault'. Read DTC B16AE-00 (Ignition Encryption). Inspection found a non-genuine driver airbag installed, causing an encryption key mismatch with the SRS ECU. Replaced the driver airbag module with a genuine unit and performed the 'Ignition Encryption Matching' procedure using VDS. Fault resolved.
BYD DTC AI Analysis

2019 BYD Yuan EV: Worn clock spring causes intermittent fault

✓
The owner reported an intermittent airbag warning light, particularly when turning the steering wheel. The scan tool showed codes B16AE and B165D (driver igniter fault). Disassembly revealed poor internal contact in the clock spring (spiral cable), causing resistance fluctuations in the driver airbag igniter circuit and interruption of encrypted communication. Replaced the clock spring and the fault cleared.
BYD DTC AI Analysis

2020 BYD Qin Petrol SRS ECU Software Fault

✓
The vehicle has no accident history. During normal driving, the airbag warning light suddenly illuminated with DTC B16AE-00 present. Inspected all wiring harnesses and airbag resistance—readings normal, no faults found. Checked the TSB and identified an encryption algorithm bug in the SRS ECU software for this production batch. Solution: Upgraded SRS ECU software to V2.3. Cleared the fault code; it has not returned.
BYD DTC AI Analysis

2019 BYD Song MAX airbag system fault after water ingress

✓
After driving through water, the dashboard displayed multiple safety system warning lights. Retrieved fault codes included B16AE (ignition immobiliser) and B1600 (power supply fault). Inspection revealed water ingress into the floor wiring harness connectors, causing unstable voltage supply to the SRS ECU and a short circuit in the ignition circuit. Resolution: Thoroughly cleaned and dried the harness connectors, replaced the damaged airbag wiring harness, and resealed for waterproofing.
Other Qin Plus 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.