AU
C001D00

This DTC indicates a drive circuit fault for the Right Rear Outlet Valve inside the Intelligent Integrated Braking System (IPB) electro-hydraulic module — Seal U

Braking System

This DTC indicates a drive circuit fault for the Right Rear Outlet Valve inside the Intelligent Integrated Braking System (IPB) electro-hydraulic module.

The outlet valve is a key actuator in the ABS/ESP hydraulic modulator.

During the pressure reduction phase, it routes brake fluid from the right rear wheel cylinder back to the reservoir to reduce wheel cylinder pressure.

A drive fault typically indicates the ECU detected an open or short circuit in the solenoid valve coil, abnormal drive current, or a damaged power stage circuit (MOSFET/driver chip).

This fault disables the right rear wheel ABS/ESP pressure reduction function and forces the system into a degraded protection mode (ABS/ESC functions limited or disabled).

Symptoms include a hard brake pedal, increased braking distance, and, in extreme cases, compromised vehicle stability control.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Open circuit or inter-turn short circuit in the right rear outlet valve solenoid coil inside the IPB electro-hydraulic module, causing the drive current to exceed the threshold range.
  • 2IPB control board power drive circuit fault, such as a damaged intelligent high-side/low-side switch chip, shorted drive MOSFET, or faulty sampling resistor.
  • 3Mechanical binding of the hydraulic valve body (debris, corrosion, or seal ring fragments) causes excessive resistance to solenoid valve movement, resulting in continuously high drive current that triggers protection.
  • 4Poor contact in the IPB module low-voltage power supply or ground circuit causes the drive voltage to drop, preventing the buildup of sufficient electromagnetic force to drive the valve spool.
  • 5IPB control software fault or calibration parameter drift causing incorrect valve drive timing or improper diagnostic threshold settings (intermittent false alarm)
What To Do
  • 1
    Use the BYD VDS or a dedicated diagnostic tool to read all DTCs. Confirm C001D00 is a current active fault and record freeze frame data (vehicle speed, brake pressure, voltage, etc.).
  • 2
    Visually inspect the IPB electro-hydraulic module to confirm no impact damage, brake fluid leakage, or signs of corrosion or water ingress at the connector. Check the continuity and insulation of the related wiring harnesses (power, ground, CAN).
  • 3
    Perform the IPB actuator self-test (Actuator Test) and listen for a clear 'click' from the right rear outlet valve. If no sound occurs or the diagnostic tool indicates a drive failure, confirm an internal fault.
  • 4
    Measure the resistance between the right rear outlet valve drive pin and the internal coil at the IPB connector (normal: approx. 2-8 Ω). If the resistance is infinite (open circuit) or close to 0 Ω (short circuit), this indicates an internal solenoid valve fault.
  • 5
    If confirming an internal IPB fault, replace the IPB electro-hydraulic module assembly with ECU (the part number must match the vehicle model; e.g., Song PLUS DM-i requires the corresponding hardware version).
  • 6
    After replacement, perform the complete repair procedure: bleed the brake lines (use dedicated bleeding equipment or activate the pump motor with a diagnostic tool), calibrate the yaw rate sensor, calibrate the longitudinal acceleration sensor, perform IPB function self-learning, and verify with a road test.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i IPB Internal Solenoid Short Circuit Replacement Case

✓
Vehicle mileage 28,000 km. ABS and ESP warning lights lit up suddenly while driving; the instrument panel displayed "Check Brake System." VDS found C001D00 (current fault) and C001C04 (right rear inlet valve fault). Inspected the IPB connector: no abnormalities. Measured resistance at the right rear valve body drive pins: only 0.8Ω (severe short circuit). Disassembled the IPB: internal PCB driver chip burnt, hydraulic valve body coil insulation damaged. Replaced the IPB assembly, performed brake bleeding and sensor calibration. Fault resolved.
BYD DTC AI Analysis

IPB Right Rear Valve Body Drive Fault Repair After Water Ingress

✓
After driving through standing water, multiple brake system warning lights came on. The scan tool showed C001D00 and multiple wheel speed sensor faults. Inspection found water pooling beneath the IPB mounting location; the connector seal had aged, allowing moisture ingress. Cleaning and drying the connector did not clear C001D00. Further testing revealed moisture had penetrated the IPB internals, corroding the right rear outlet valve drive circuit open. Replaced the IPB assembly and improved waterproofing at the mounting location to resolve the fault.
BYD DTC AI Analysis

IPB software refresh resolved intermittent outlet valve driver fault

✓
Intermittent ABS warning light reported; cleared on restart. Scanner read C001D00 as a history fault with current status normal. Wiring harness, connectors, and power supply checked normal. Solenoid valve resistance within range. Root cause: IPB control software falsely flagged a drive fault under specific conditions (low-voltage cranking or transient electromagnetic interference). Flashed IPB ECU to the latest software version, cleared fault codes post-flash. Monitored for one month; no recurrence.
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.