AU
C056364

DTC C056364 indicates the ABS control module inside the IPB (Intelligent Integrated Brake System) detects an internal operating fault — Seal U

Braking System

DTC C056364 indicates the ABS control module inside the IPB (Intelligent Integrated Brake System) detects an internal operating fault.

The IPB is BYD's one-box brake-by-wire solution (such as the Bosch IPB or BYD in-house IPB), integrating ABS, ESC, regenerative braking, automatic emergency braking, and other functions.

Sub-code 64 usually indicates a control module internal self-test failure, involving a main control chip (MCU) fault, abnormal power supply voltage monitoring, internal memory (Flash/RAM) errors, a solenoid valve drive circuit fault, or a watchdog reset.

This fault causes ABS, ESC, TCS, AEB, and other functions to fail or enter degraded mode.

The instrument cluster illuminates the ABS and ESC warning lights, and the vehicle may limit power output.

The vehicle usually retains basic hydraulic braking (the brake pedal may feel hard).

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Abnormal IPB module internal ECU power supply circuit: Unstable 12V constant power (B+) or ignition power (IGN) voltage, blown fuse, or poor relay contact causes the module supply voltage to drop below 9V or exceed 16V, triggering protection.
  • 2Internal hardware fault in the IPB electro-hydraulic module: main control chip damage, internal memory data corruption, solenoid valve driver chip overheating or burnout, PCB water ingress and corrosion (especially after car washing or wading)
  • 3Wiring harness and connector issues: Loose IPB module connector, backed-out terminals, water ingress causing oxidation, or wiring harness wear causing intermittent open or short circuits that affect power supply, ground, or CAN communication.
  • 4Ground system fault: Loose or oxidized IPB module ground wire connections (G101/G102, etc.) cause excessive ground resistance (>1Ω), resulting in reference voltage drift.
  • 5Software defect or calibration error: IPB control software version contains a bug or the calibration data CRC check fails, causing a module self-check failure.
What To Do
  • 1
    Diagnostic tool check: Use VDS2000/3000 or Launch X431 to read complete fault codes and record freeze frame data. Check for accompanying U-class communication faults or power supply fault codes (e.g., C003F00, C004000). Analyze parameters such as vehicle speed and voltage at the time of the fault.
  • 2
    Power and ground check: Measure voltage at IPB module connector Pin 1 (constant power 30) and Pin 2 (ignition power 15). Standard value: 12V ± 0.5V. Measure resistance between Pin 13/26 (ground) and body ground. Standard value: <1Ω. Check IPB-related fuses in the engine compartment fuse box, such as F1/14 and F2/11.
  • 3
    Communication line check: Disconnect the IPB connector. Measure the voltage to ground for CAN-H (Pin 16) and CAN-L (Pin 17) (should be approximately 2.6 V and 2.4 V respectively). Measure the termination resistance (with power off, the resistance between CAN-H and CAN-L should be approximately 60 Ω, representing two 120 Ω terminating resistors in parallel).
  • 4
    Visual and physical inspection: Inspect the IPB electro-hydraulic module (located near the engine compartment firewall) for impact deformation, brake fluid leaks, water ingress at the connector (green corrosion), or signs of overheating. Check the brake fluid level and condition.
  • 5
    Software procedure: Attempt to clear the fault code. If the code clears, upgrade the IPB system software to the latest version (e.g., for Song PLUS DM-i, upgrade to a post-2023 version) and rewrite the calibration data. If the code fails to clear or frequently recurs, perform a power reset (disconnect the battery negative terminal for 10 minutes).
  • 6
    Replacement verification: If the above checks are normal but the fault persists, replace the IPB electro-hydraulic module assembly with ECU (e.g., part number BYD-3530100-XX). After replacement, perform: ① Brake system bleeding procedure ② Pressure sensor calibration ③ Longitudinal acceleration sensor calibration ④ Yaw rate sensor calibration ⑤ Road test to verify ABS/ESC function.
  • 7
    System verification: After repair, perform emergency braking tests at 20km/h and 40km/h on a flat, straight road. Verify normal ABS operation, check that the instrument cluster warning light is off, and verify the diagnostic tool shows no current fault codes.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i ABS warning light stays on after car wash

✓
After the vehicle waded through water and was washed, the ABS and ESC warning lights lit up simultaneously. Read DTC C056364 (current fault). Found the IPB electro-hydraulic module at the lower left of the firewall; the connector cover was poorly sealed with visible water and green corrosion inside. Disconnected the connector, cleaned the oxidation, applied conductive adhesive, and replaced the seal, but the fault persisted. Power supply tested normal. Determined water had entered the ECU and shorted the circuit board. Replaced the IPB assembly (P/N 3530100A-02) and performed calibration; fault cleared. Check the IPB connector seal after water exposure and install a waterproof cover if necessary.
BYD DTC AI Analysis

Intermittent brake system warning while driving — BYD Seal EV

✓
Customer reported intermittent dashboard warning "Braking System Fault" during high-speed driving. DTC C056364 was intermittent. Inspection found slight burn marks on IPB power supply fuse F1/14. Contact resistance at the fuse holder measured 2.3Ω (standard <0.1Ω). Disassembly revealed oxidized fuse blades and chafing on the IPB wiring harness at the battery bracket, with copper wire partially exposed. Replaced fuse and holder, repaired chafed wiring (added corrugated tube protection), and resecured routing. Fault did not recur. Intermittent faults like this usually stem from contact resistance; check power circuit voltage drop.
BYD DTC AI Analysis

Han DM-i software conflict caused false alarm.

✓
During new vehicle PDI, found fault code C056364. Cleared it, but the code returned after restart. Checked power, ground and CAN wiring – all normal, no physical damage. Consulted technical bulletins: this VIN is within TPI-2023-025 scope. IPB software V1.02 has an initialization logic defect that triggers false code C056364 when C003100 is present (left front wheel speed sensor fault; actually due to spare tire sensor not installed). Updated IPB software to V1.05 and masked fault codes for the sensors not installed. System self-check passed; fault fully resolved.
BYD DTC AI Analysis

Qin PLUS IPB fault after collision repair

✓
Following front-end collision repairs that replaced the front bumper and left wing, the instrument cluster showed a brake system fault. Scanned DTCs C056364 and C055F92 (hydraulic system fault). Inspection found the accident had slightly deformed the IPB module housing, damaging the internal pressure sensor, while the ECU triggered protective fault codes after detecting hydraulic circuit abnormalities. Replaced the IPB assembly and thoroughly bled the system, but C056364 would not clear. Further inspection found the repairer had mistakenly mounted the IPB earth wire to a painted surface, with 8.5Ω resistance to earth. Sanded the earthing point to bare metal, retightened the connection, and cleared the fault.
BYD DTC AI Analysis

Tang DM-p module damage after long-term parking

✓
Vehicle sat parked for three months. On startup, multiple warning lights illuminated on the instrument cluster including ABS, ESC, and EPB. The scan tool read DTCs C056364 (history) and C056E00 (EPB communication fault). Measured battery voltage at only 10.2V. After jump-starting, the IPB module internal relay chattered continuously. Determined prolonged low voltage caused overcurrent damage to the IPB internal boost circuit, and unstable ECU supply triggered the fault codes. Replaced the IPB assembly and battery (excessive internal resistance). Fault resolved. Advised the customer to disconnect the battery negative terminal before long-term storage to prevent IPB static current from draining the battery and causing reverse surge damage.
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.