AU
B169416

DTC B169416 indicates the airbag control unit (SRS ECU) detects an internal operating voltage below the calibrated threshold (typically below 9V), or a functional fault in the ECU internal power management module or voltage regulation circuit — Qin Plus

Safety System

DTC B169416 indicates the airbag control unit (SRS ECU) detects an internal operating voltage below the calibrated threshold (typically below 9V), or a functional fault in the ECU internal power management module or voltage regulation circuit.

This hardware-level fault indicates the SRS ECU cannot maintain the stable operating voltage required for its internal microprocessor, acceleration sensor, and ignition circuit.

When triggered, the ECU enters fail-safe mode.

This condition can cause complete airbag system failure (airbags fail to deploy during a collision), prevent seat belt pretensioner activation, or generate a false alarm resulting in unintended airbag deployment.

This fault poses a severe safety risk and requires immediate repair.

The B169416 fault code on the Qin Plus indicates the airbag control unit (SRS ECU) has detected low internal voltage or a power management fault, preventing stable operation of critical safety systems. Severity is medium. Common causes include a damaged internal voltage regulator or low battery/charging system voltage. Immediate repair at an authorised dealer is required. Typical repair cost data is available from 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1A damaged SRS ECU internal power management chip or voltage regulation circuit fails to convert battery voltage into a stable 5V/3.3V internal operating voltage.
  • 2Severely discharged vehicle battery, generator fault, or excessive voltage drop in the dedicated SRS power supply circuit, causing the ECU input voltage to remain below 9V.
  • 3Oxidation, terminal back-out, or poor contact at the SRS ECU connector pins (usually located under the center console), causing an abnormal increase in power supply circuit resistance.
  • 4Loose or corroded ECU ground harness (G301 or G302 ground point) causing reference ground potential drift and abnormal voltage detection.
  • 5After a collision, the internal crash sensor in the SRS ECU triggers fuse protection or a software lock (Crash Data Locked). Replace the module.
What To Do
  • 1
    Use a BYD VDS2000 or Launch X431 diagnostic tool to read the complete fault code stream. Confirm B169416 is active. Check for accompanying fault codes such as B1694-00 (power supply voltage too low) or U0151 (lost communication with SRS). Record the voltage value in the freeze frame data.
  • 2
    Measure the battery static voltage (should be ≥12.4V) and the charging voltage after startup (should be 13.5-14.5V). Check if the SRS ECU fuse (F1/15, usually 10A or 15A) in the instrument panel fuse box is blown. Measure the voltage between ECU connector pin 1 (constant power) and body ground.
  • 3
    Disconnect the 12 V battery negative terminal and wait 3 minutes (to discharge capacitors). Remove the trim panels on both sides of the centre console and remove the SRS ECU module (part number usually starts with 5A or 6A). Inspect the 32-pin connector for water ingress, green pin oxidation, or backed-out pins. Measure the resistance between the power supply pin and the ground pin (<1 Ω).
  • 4
    If the circuit voltage is normal (12V±0.5V) and the ground is good, but the fault code will not clear, diagnose an internal ECU fault and replace the SRS ECU assembly. (Note: Match the vehicle configuration code; do not mix ECUs from different airbag configuration versions.)
  • 5
    After installing the new ECU, perform Online Programming, write the Vehicle Configuration, and perform Zero Point Calibration for the crash sensor. Clear the fault codes, then perform a System Check to confirm the airbag warning light is off and communication is normal.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM airbag warning light suddenly illuminated while driving

✓
Vehicle: 2019 Qin Pro DM, 32,000 km. Symptom: While driving, the airbag warning light on the dashboard suddenly illuminated and stayed on. No accident history. Diagnosis: Scanned with VDS and retrieved current fault code B169416. Freeze frame data showed ECU voltage at 8.2 V. Measured battery voltage (normal). Inspected the SRS ECU connector and found slight oxidation on pin 1 (power supply); contact resistance measured 3.2 Ω. Fix: Cleaned pin 1 with electronic contact cleaner, applied conductive grease, and re-tightened the connector. Cleared the fault code. Followed up for one month—no recurrence.
BYD DTC AI Analysis

BYD E2 new car SRS system no communication

✓
Vehicle: 2020 BYD E2 EV, new vehicle PDI inspection. Symptom: Airbag warning light stays on, scan tool cannot communicate with SRS ECU. Diagnosis: Checked OBD pins 6 and 14 (CAN lines) — normal. No voltage at SRS ECU connector. Found loose SRS fuse slot in dashboard fuse box. Voltage intermittent when wiggling the fuse. Repair: Replaced fuse box base and tightened fuse pins. Fault resolved. Issue due to supplier assembly process.
BYD DTC AI Analysis

Qin EV showing SRS ECU fault after accident repair

✓
Vehicle details: 2019 Qin EV. Front collision, replaced front bumper and left front crash sensor. Symptom: After repairs, started the vehicle. Airbag light stays on. Read DTCs B169416 and B165C (front crash sensor fault). Diagnosis: Checked new sensor wiring – OK. The SRS ECU had recorded crash data and triggered its lockout protection. Standard unlock methods failed. Repair: Replaced SRS ECU (part number 5A-3638010C), performed online programming and sensor matching. Fault resolved.
BYD DTC AI Analysis

E3 SRS system low voltage fault after long-term parking

✓
Vehicle: 2020 E3. Started after sitting for 2 months. Symptoms: Hard starting, airbag warning light on, logged DTC B169416. Diagnosis: Battery voltage was only 10.5V. After charging, voltage returned to normal but the fault code persisted. Further inspection revealed aged capacitors inside the ECU; these could not maintain stable operating voltage after the high current surge during cold starting. Resolution: Replaced the SRS ECU and the battery. Advised the customer to disconnect the battery negative terminal for extended parking.
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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.