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 — Atto 8

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.

The C001D00 fault code on the Atto 8 indicates a medium-severity drive circuit fault in the right rear outlet valve of the IPB braking module. This can limit or disable ABS/ESC pressure reduction at the right rear wheel. Common causes include an open or shorted outlet valve solenoid coil, or a failed IPB control board driver circuit. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Open circuit or inter-turn short circuit in the right rear outlet valve solenoid coil inside the IPB electro-hydraulic module causes the drive current to exceed the threshold range.
  • 2IPB control board power drive circuit fault, such as damaged intelligent high-side/low-side switch chip, drive MOSFET breakdown, or faulty sampling resistor.
  • 3Mechanical binding in the hydraulic valve body (due to contamination, corrosion, or seal debris) causes excessive resistance to solenoid valve movement, resulting in a continuous 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 module from generating 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 BYD VDS or a dedicated diagnostic tool to read complete DTCs, confirm C001D00 is currently active, and record freeze frame data (vehicle speed, brake pressure, voltage, etc.).
  • 2
    Visually inspect the IPB electro-hydraulic module for impact damage, brake fluid leakage, and corrosion or water ingress at the connector. Check the continuity and insulation of the relevant wiring harnesses (power, ground, CAN).
  • 3
    Run 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 shows 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; for example, Song PLUS DM-i requires the corresponding hardware version).
  • 6
    After replacement, perform the complete repair procedure: bleed the brake lines (requires dedicated bleeding equipment or a diagnostic tool to activate the pump motor), calibrate the yaw rate sensor, calibrate the longitudinal acceleration sensor, perform IPB function self-learning, and verify via 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 Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.