AU
P056024

DTC P056024 indicates the IPB (Integrated Power Brake) detects a switch or attempted switch to the UBVR (Unified Backup Voltage Regulator) power supply mode — Qin Plus

Braking System

DTC P056024 indicates the IPB (Integrated Power Brake) detects a switch or attempted switch to the UBVR (Unified Backup Voltage Regulator) power supply mode.

In the BYD IPB system, the UBVR is the internal backup power management unit.

When the main power supply (typically constant 12V power) experiences a voltage drop, instability, or failure, the system triggers a redundant power supply mechanism to maintain critical braking functions.

This DTC indicates: 1) abnormal main power supply voltage causing an automatic system switch; 2) a fault in the UBVR switching circuit; 3) an internal power management logic error within the IPB module.

This fault may affect functions including ABS, ESC, and Automatic Emergency Braking, risking degraded braking performance.

The P056024 fault code on the Qin Plus indicates the IPB braking system has detected a switch or attempted switch to its backup power supply mode. This is a medium severity issue because ABS, ESC, or automatic emergency braking may be degraded. Common causes include a weak 12V battery or loose, corroded IPB power connections. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1An aging or undercharged low-voltage battery (12V battery) causes a sudden voltage drop during startup or driving, triggering backup mode.
  • 2Poor contact, loose connection, or corrosion in the IPB module power supply circuit causing intermittent supply voltage interruption.
  • 3DC-DC converter fault (DM-i models) causes unstable high-voltage to low-voltage output, failing to meet IPB operating voltage requirements.
  • 4Fault in the IPB electro-hydraulic module internal power management circuit or UBVR changeover relay, causing a false alarm or failure to switch back to the main power supply.
  • 5Prolonged vehicle parking or frequent short-distance driving prevents the battery from fully charging, leaving the system voltage at a critical level.
What To Do
  • 1
    Use the VDS2000/3000 diagnostic tool to read the complete fault code stream, determine if P056024 is a current or history fault, and check the system voltage in the freeze frame data.
  • 2
    Measure the low-voltage battery static voltage (should be ≥12.4V) and dynamic voltage during startup/driving (should stabilize at 13.5-14.5V). Check the battery state of health (SOH). Charge or replace the battery if necessary.
  • 3
    Check the IPB module power fuse (usually F1/18 or F2/17, depending on vehicle configuration), power wire (B+), and ground wire (GND) for tightness. Measure the voltage drop; it must be <0.1V.
  • 4
    Disconnect the IPB module connector. Check the terminals for push-out, oxidation, or water ingress. Measure the voltage stability of the power supply terminal. For DM-i models, also check the DC-DC output voltage.
  • 5
    If the wiring is normal but the fault occurs intermittently, update the IPB module software to the latest version. If the update is ineffective or the fault persists, replace the IPB integrated electro-hydraulic brake assembly, and perform bleeding calibration and ESC yaw sensor learning.
Real-World Cases
BYD DTC AI Analysis

Aging 12V battery in Song PLUS DM-i intermittently triggers P056024

✓
After sitting parked for 3 days, the vehicle started with ABS/ESC warning lights on. Scanned DTC P056024 (current). Static battery voltage measured only 11.8V; load test showed excessive internal resistance. Replaced the OEM 12V battery (60Ah AGM), cleared the DTC, and followed up for one month with no recurrence. Analysis: The aged battery caused cold-cranking voltage to drop below 10V, triggering the IPB to enter UBVR mode for protection.
BYD DTC AI Analysis

Internal power chip failure in IPB module causing persistent DTCs

✓
The brake system warning light illuminated suddenly while driving. P056024 was present and could not be cleared. Battery voltage measured normal at 14.2V; IPB power supply harness showed no abnormalities. Disassembled the IPB module and found the MOSFET in the UBVR switching circuit on the internal PCB burnt out. Replaced the IPB assembly to resolve the fault. Old part analysis revealed batch components had insufficient voltage rating.
BYD DTC AI Analysis

Water ingress into the wiring harness connector caused oxidation and poor contact.

✓
Brake system fault after driving through water. Diagnostic tool displayed P056024 and related communication faults. Checked the IPB module harness connector in the engine bay and found mud and water inside, with obvious oxidation and blackening on the power supply terminals (Pin 1/32). Cleaned the connector, applied conductive paste, and replaced the waterproof seal; fault cleared. Recommend checking the engine bay seals.
BYD DTC AI Analysis

Software version bug caused false positive (fixed via OTA)

✓
Multiple Song PLUS DM-i owners reported intermittent P056024 DTCs, but hardware inspections found no faults. A technical bulletin identified an overly sensitive power management strategy in IPB control unit software V1.2. Technicians upgraded the software to V1.4, optimizing the UBVR switching threshold from 12.0V to 11.5V. The fault rate dropped significantly after the upgrade.
BYD DTC AI Analysis

DC-DC converter output instability causes voltage fluctuations

✓
Fault code P056024 set when driving in HEV mode; EV mode operated normally. DC-DC output voltage measured fluctuating widely between 13.0-15.2V (should be stable at 14.0±0.2V). Inspection found loose DC-DC high-voltage input terminals causing power instability. Tightened the high-voltage connectors and updated the DC-DC control software. IPB power supply stabilized and the fault code has not returned.
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.