AU
B2A0717

This DTC indicates the A/C controller or thermal management system control module detects a power supply voltage exceeding the 16V safety threshold — Qin Plus

Thermal Management System

This DTC indicates the A/C controller or thermal management system control module detects a power supply voltage exceeding the 16V safety threshold.

In BYD new energy vehicles, the DC-DC converter typically converts high-voltage traction battery energy to power the low-voltage system (12V/14V system).

Normal output voltage should range between 13.5V and 14.5V.

When the monitoring point voltage continuously exceeds 16V, the controller identifies an overvoltage condition and triggers a protection mechanism to prevent electronic component damage.

This fault may restrict A/C system functions, reduce thermal management efficiency, or force the system into a power derating mode.

Extreme cases may damage sensitive electronic components on the control board.

The '161' in the DTC typically refers to a specific voltage monitoring circuit or sensor number.

The B2A0717 fault code on the Qin Plus indicates the A/C controller or thermal management module has detected low-voltage system power above the 16V safety limit. Severity is medium because it can limit A/C or thermal management operation and may damage electronics. Common causes include a faulty DC-DC converter voltage regulator or an A/C controller voltage sensing fault. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1DC-DC converter output voltage regulation failure causing the low-voltage side output voltage to abnormally exceed 16V.
  • 2A/C controller internal power management chip or voltage sampling circuit fault, causing a false overvoltage report.
  • 312V low-voltage battery aging, sulfation, or poor connection causing voltage fluctuations and transient overvoltage spikes.
  • 4Generator voltage regulator fault (for hybrid models equipped with a starter-generator), causing excessive charging voltage.
  • 5Poor contact, loose connection, or poor ground in the air conditioning controller power supply circuit, causing the sampling point reference voltage to drift.
What To Do
  • 1
    Use the VDS2000/VDS1000 diagnostic tool to read the complete fault codes and freeze frame data. Record the specific voltage value and environmental conditions when the overvoltage occurred. Confirm whether B2A0717 is a current or history fault.
  • 2
    Measure the low-voltage battery static voltage (vehicle off) and dynamic voltage (OK/Ready state). Confirm whether the actual DC-DC output voltage exceeds 16V to determine if the overvoltage is genuine or a false sensor report.
  • 3
    Check the A/C controller fuse, relay, and power supply wiring connections. Inspect the power and ground wires from the BMS compartment and front compartment distribution box to the A/C controller for poor contact, oxidation, or burn damage.
  • 4
    Disconnect the air conditioning controller connector and measure the voltage between the controller-side power pin and ground. If the voltage is normal, replace the air conditioning controller assembly. If the voltage remains too high, inspect the DC-DC converter and upstream power distribution circuit.
  • 5
    Check the DC-DC converter output characteristics. If necessary, update the DC-DC control software or replace the DC-DC assembly. Verify the output voltage remains stable within the 13.8V-14.5V range.
  • 6
    After repairing or replacing the faulty component, clear the fault code. Perform an air conditioning system self-test and run the system for at least 15 minutes under different operating conditions (cooling/heating/MAX mode) to confirm the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

B2A0717 Overvoltage Fault: Basic Definition and Troubleshooting

✓
AC system or related control module logged voltage overvoltage fault, potentially restricting AC function, causing control panel anomalies, or triggering protective shutdown. VDS scan retrieved DTC B2A0717 (161 Voltage Overvoltage), localized to the power supply circuit. Measured supply voltage to relevant sensors and control module exceeded system calibration threshold (e.g., above 16V). Fix involved checking generator output, voltage regulation module and wiring; replacing the faulty voltage regulator or repairing shorts/poor connections causing the voltage anomaly.
Original source ↗
BYD DTC AI Analysis

BYD Air Conditioning Controller Abnormal Voltage Fault

✓
With the A/C on, the control panel intermittently goes black or displays "Please check air conditioning system". Cooling is intermittent and the system fault light comes on. VDS scanning revealed A/C controller fault codes (similar to B2A series power faults). Voltage measurements at the controller supply pins showed excessive fluctuation or sustained overvoltage, setting DTC B2A0717. Inspection of the power circuit found a failed voltage regulator module. Replaced the A/C controller power supply voltage regulator module, repaired the harness contact issues, and cleared the codes. System returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD New Energy Vehicle High Voltage Interlock Loop Voltage Fault

✓
Dashboard shows "EV Function Limited" or "Check Powertrain". Vehicle cannot enter EV mode and intermittently fails to ready up. VDS scan reveals voltage-related DTCs in the BMS or HVAC thermal management system (refer to B2A series). Check the power wiring between the high voltage distribution box and AC controller; overvoltage present. Voltage at sensor No. 161 or the control point measures outside the normal range. Check DC-DC converter output voltage. Replace the damaged fuse or relay in the high voltage distribution box. Repair the AC controller power supply wiring. Fault resolved.
Original source ↗
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.