AU
B16AE

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

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 Seal U indicates the airbag system detected an encryption verification failure or communication error with an ignition circuit. This medium severity issue may prevent airbag deployment during a crash. Common causes include a faulty airbag ECU or loose, corroded wiring connections. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available based on 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Airbag ECU internal software error or encryption chip fault preventing correct verification of the igniter identity.
  • 2Airbag squib (driver/passenger/side airbag) wiring harness connector oxidized, loose, or with excessive contact resistance, disrupting encrypted signal transmission.
  • 3Replacing the airbag assembly with a non-genuine part or failing to perform encrypted 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 errors
  • 5Vehicle wading or high-humidity environments cause water ingress at the airbag wiring harness connector, resulting in an ignition circuit short or encrypted communication interference.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal. 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 all fault codes. Verify DTC B16AE-00 is present. Record the voltage value and squib 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 'Igniter Encryption Matching' functions using the diagnostic tool to check the encryption communication status of each igniter. If encryption fails at a specific location (such as the driver airbag), check the clock spring or wiring harness at that location.
  • 5
    Software action: If wiring is normal, attempt to update the SRS ECU software (if a new version is available) or perform an 'encryption key reset/re-matching' operation.
  • 6
    Component replacement: If diagnostics confirm an internal airbag control unit fault, replace the SRS ECU with an OEM unit and perform coding and matching. If a specific airbag module fails, replace the module and use the diagnostic tool to perform 'component encryption learning'.
  • 7
    System verification: Clear the fault code, reconnect the battery, and start the vehicle. Verify the airbag warning lamp turns off. Perform a crash sensor simulation test (using the diagnostic tool function, not a physical impact) to verify system operation.
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 Seal U Fault Codes
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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.