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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 — Seal U

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 — Seal U
  • 1Incorrect IPB ECU software version (mistakenly flashed software package for another vehicle model, model year, or trim level)
  • 2Failure to perform online matching, coding, and anti-theft synchronization after replacing the IPB assembly with a salvaged or used unit.
  • 3Interrupted software flashing (battery voltage below 12V, unstable OBD connection, or diagnostic tool crash) corrupted the program block.
  • 4Vehicle network configuration data (CVN/AS-BUILT data) missing or inconsistent with gateway module configuration.
  • 5IPB internal EEPROM data corrupted (due to prolonged battery discharge, strong electromagnetic interference, or hardware aging)
What To Do
  • 1
    Use VDS2000 or a BYD dedicated 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 power supply fluctuations causing software checksum errors.
  • 3
    Check the vehicle VIN against the 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 Update": Connect the diagnostic tool to the BYD cloud server and download the latest IPB software package (usually .hex or .s19 format) for the corresponding VIN. During flashing, maintain battery voltage above 12V and do not operate doors, air conditioning, or other high-power electrical equipment.
  • 5
    After completing the refresh, perform the 'System Configuration' (enter the correct coding value), 'Sensor Zero-Point Calibration' (calibrate the longitudinal acceleration sensor and pressure sensor), and 'Brake Line Bleeding' procedures.
  • 6
    If the software flash fails, the fault code does not clear, or the fault code returns, install a new IPB assembly. Complete online matching, coding, and brake fluid filling and bleeding.
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 Seal U 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.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.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.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.
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.