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 8

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).

The B16AE fault code on the Atto 8 indicates an airbag system encryption error where the control module cannot verify the igniter's security key or detects communication failure in the ignition circuit. Severity is medium, as this may prevent airbag deployment during a crash. Common causes include faulty airbag ECU software or corroded wiring connectors. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Airbag ECU internal software error or encryption chip fault prevents correct verification of the igniter ID.
  • 2Airbag igniter (driver/passenger/side airbag) wiring harness connector is oxidized, loose, or has excessive contact resistance, disrupting 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 encryption algorithm calculation error.
  • 5Water ingress into 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 to allow the SRS ECU capacitor to fully discharge, preventing 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); check each airbag connector (yellow plug) for oxidation or looseness, and measure the squib resistance (standard: 2.0±0.3Ω).
  • 4
    Encryption verification test: Execute the 'SRS System Self-Test' and 'Squib Encryption Matching' functions using the diagnostic tool to check the encryption communication status of each squib. If encryption fails at a specific location (e.g., driver airbag), check the corresponding clock spring or wiring harness.
  • 5
    Software procedure: If the wiring is normal, attempt to update the SRS ECU software (if a new version is available) or perform an 'encrypted key reset/re-matching' operation.
  • 6
    Component replacement: If testing confirms an internal fault in the airbag control unit, replace the SRS ECU with a genuine unit 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 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.