AU
U030000

In the BYD IPB (Intelligent Power Brake) integrated braking system, U030000 indicates the brake control unit (IPB ECU) internal software is incompatible with the vehicle network configuration — Atto 3

Braking System

In the BYD IPB (Intelligent Power Brake) integrated braking system, U030000 indicates the brake control unit (IPB ECU) internal software is incompatible with the vehicle network configuration.

Specifically, the IPB module software version number, Calibration Verification Number (CVN), or configuration word (Coding) does not match the vehicle VCU, Gateway, and other CAN nodes.

This prevents the brake control strategy from loading normally or causes verification failure.

The fault triggers the system safety protection mechanism, restricting regenerative braking, Automatic Emergency Braking (AEB), and ESC functions.

Severe cases cause a hard brake pedal, limit brake assist, or force the vehicle into limp mode.

This functional fault compromises driving safety.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Incorrect IPB ECU software version (incorrectly flashed software package for a different vehicle model, model year, or trim level)
  • 2Failure to perform online matching, coding, and immobilizer synchronization after replacing the IPB assembly with a salvaged or used unit.
  • 3Software flashing interruption (battery voltage below 12V, unstable OBD connection, or diagnostic tool crash) causes program block corruption
  • 4Vehicle network configuration data (CVN/AS-BUILT data) missing or inconsistent with gateway module configuration.
  • 5IPB internal EEPROM data corruption (due to prolonged battery discharge, strong electromagnetic interference, or hardware aging).
What To Do
  • 1
    Use VDS2000 or a dedicated BYD diagnostic tool to read the fault code. Confirm U030000 is a current fault, not a history fault. Record the current IPB software version number (e.g., BGM+ version number) and hardware part number.
  • 2
    Check the IPB ECU power supply (constant power 30+B, ignition switch IG power), ground points (G101/G102), and CAN-H/CAN-L voltages (recessive 2.5V, dominant 3.5V/1.5V) to rule out software checksum errors caused by power supply fluctuations.
  • 3
    Check the vehicle VIN and IPB label part number to confirm the hardware matches the vehicle configuration (e.g., Song PLUS DM-i requires a specific IPB model; do not mix petrol and hybrid IPBs).
  • 4
    Perform "online programming" or "software refresh": Connect the diagnostic tool to the BYD cloud server and download the latest IPB software package for the corresponding VIN (usually in .hex or .s19 format). During flashing, maintain battery voltage above 12V and do not operate high-power electrical equipment such as doors or air conditioning.
  • 5
    After completing the update, perform the 'System Configuration' (enter the correct Coding code), 'Sensor Zero Point Calibration' (calibrate the longitudinal acceleration sensor and pressure sensor), and 'Brake Line Bleeding' procedures.
  • 6
    If the software update fails, or the fault code will not clear or returns, install a new IPB assembly. Perform online matching and coding, then fill and bleed the brake fluid.
Real-World Cases
BYD DTC AI Analysis

Replaced IPB assembly with used unit; DTC U030000 now present.

✓
A 2021 Song PLUS DM-i had its IPB assembly replaced with a salvage unit after an accident. After installation, the ABS and ESC warning lights came on in the instrument panel with DTC U030000. Diagnosis revealed the salvage part came from a gasoline Song Pro with incompatible software. Technicians used VDS2000 to run the 'Replace ECU' procedure, performing online programming and writing the Song PLUS DM-i Coding. Pressure sensor calibration cleared the fault.
BYD DTC AI Analysis

Interrupted software update locked up the module

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During IPB software upgrade, loose USB connection on diagnostic tool interrupted programming. DTC U030000 could not be cleared afterwards, and IPB could not enter programming mode. Forced flash in Boot mode after power-down/sleep failed. Replaced IPB assembly. Use regulated power supply (14V/50A) before flashing. Do not rely solely on vehicle battery.
BYD DTC AI Analysis

Software verification failed after 12V battery discharge

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Vehicle sat for one month; battery voltage dropped to 8.5V. After jump-starting, the instrument cluster displayed 'Braking system fault' and the scan tool retrieved DTC U030000. Prolonged low voltage caused an EEPROM data checksum failure in the IPB. Performed a 'software reset' with the scan tool and reflashed the same software version. Fault code cleared and functions returned to normal without hardware replacement.
BYD DTC AI Analysis

CVN data lost after accident repair

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Replaced the gateway module and IPB following front-end collision repairs. Post-repair, DTC U030000 set and AEB failed. The new gateway module's CVN (configuration data) did not match the original vehicle, preventing the IPB from recognising the network configuration. Downloaded the original vehicle backup data via the BYD DMS system and reprogrammed both the gateway and IPB. Synchronised the network configuration to clear the fault.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.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.
Common problems reported for Atto 3 →Atto 3 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.