AU
B16AE

DTC B16AE indicates the Supplemental Restraint System (SRS) detects a squib encryption verification failure or abnormal encrypted communication in the ignition circuit — Atto 3

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).

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 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 with excessive contact resistance, affecting encrypted signal transmission.
  • 3Installing a non-genuine airbag assembly or failing to perform encryption matching after accident repairs causes an encryption key mismatch between the new and old components.
  • 4Abnormal SRS ECU power supply (voltage below 9V or above 16V) causing an encryption algorithm calculation error.
  • 5Water ingress at the airbag wiring harness connector due to vehicle wading or high humidity, 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 the code 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 all airbag connectors (yellow plugs) for oxidation or looseness; measure the squib resistance (standard 2.0 ± 0.3 Ω).
  • 4
    Encryption verification test: Perform the 'SRS System Self-test' and 'Squib Encryption Matching' functions using the diagnostic tool. Check the encrypted communication status of each squib. If encryption fails at a specific location (such as the driver airbag), check the clock spring or wiring harness at that location.
  • 5
    Software procedure: If wiring is normal, update the SRS ECU software (if a new version is available) or perform an 'encryption key reset/re-matching' operation.
  • 6
    Component Replacement: If testing confirms an internal fault in the airbag control unit, replace with a genuine 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 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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.