AU
C001000

This DTC indicates the IPB (Intelligent Integrated Braking System / One-Box Integrated Braking System) ECU detected an electrical fault in the left front inlet valve (normally open valve) drive circuit — Atto 3

Braking System

This DTC indicates the IPB (Intelligent Integrated Braking System / One-Box Integrated Braking System) ECU detected an electrical fault in the left front inlet valve (normally open valve) drive circuit.

The inlet valve is a key solenoid valve in the ABS/ESC hydraulic modulator.

It controls the brake fluid path from the brake master cylinder to the left front wheel brake cylinder.

A "drive fault" occurs when the ECU detects an abnormal circuit condition while supplying power to the solenoid valve coil (typical resistance 3-6Ω) through the driver chip (usually an H-bridge driver or high-side drive MOSFET).

These abnormal conditions include an open coil circuit, short to power, short to ground, driver chip over-temperature protection, or an abnormal drive circuit power supply.

This fault prevents the left front wheel from establishing normal ABS/ESC pressure regulation and triggers system degradation (ABS/ESC function limited or disabled).

The system retains only basic hydraulic braking, severely compromising vehicle active safety performance.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Open circuit or inter-turn short circuit in the left front inlet valve solenoid coil inside the IPB electro-hydraulic module (valve body assembly fault, possibly with brake fluid contamination or overheating)
  • 2IPB ECU internal drive circuit damage, such as power MOSFET breakdown or failure of the corresponding drive chip channel (e.g., L9369/L99MC6 dedicated chips)
  • 3Poor contact, terminal back-out, or pin corrosion/oxidation at the internal wiring harness or external connector between the IPB electro-hydraulic module and the ECU (common after vehicle wading or chassis submersion).
  • 4Severely contaminated brake fluid (excessive water content or impurities) causes the solenoid valve spool to stick, resulting in abnormal drive current that triggers a protective fault code.
  • 5Abnormal IPB power supply or ground circuit (voltage fluctuation, poor ground), causing insufficient solenoid valve drive voltage or signal drift.
What To Do
  • 1
    In-depth diagnostic check: Use VDS or a dedicated BYD diagnostic tool to read the complete fault code stream. Confirm if C001000 is a current (Active) or historical fault. Check for accompanying fault codes (such as C001001-C00100F series wheel cylinder valve faults or C003000 series pressure sensor faults) to determine if a systemic fault exists.
  • 2
    Basic inspection: Inspect the IPB electro-hydraulic module exterior for leaks or impact damage. Verify the IPB wiring harness connector (usually located near the firewall) is secure, and inspect for water ingress or signs of corrosion. Measure the battery voltage and verify the IPB main power supply and ground are normal (standard 12V system, operating voltage 9-16V).
  • 3
    Solenoid valve coil inspection: Disconnect the IPB connector and use a multimeter to measure the left front inlet valve coil resistance (standard value is typically 3.0-6.0Ω; refer to the workshop manual for exact specifications). If the resistance is infinite (open circuit) or close to 0Ω (short circuit), this indicates an internal IPB valve body fault.
  • 4
    Active test and oscilloscope check: Connect the diagnostic tool and perform the 'solenoid valve actuation test'. Use an oscilloscope to monitor the drive waveform at the ECU output terminal. The oscilloscope should display a 12V square-wave pulse. If the ECU sends a drive command but outputs no voltage, this indicates an ECU drive circuit fault. If the ECU outputs voltage but the solenoid valve does not operate, this indicates mechanical sticking in the valve body.
  • 5
    Repair or replace: If testing confirms an internal IPB fault (valve body or ECU), replace the complete IPB electro-hydraulic module assembly (BYD typically does not offer separate repair for the ECU or valve body components). After replacement, perform: 1) Brake system bleeding procedure (use a dedicated diagnostic tool to activate the motor pump for bleeding); 2) ESC sensor calibration (yaw rate and longitudinal acceleration sensor zero-point calibration); 3) Road test to verify ABS/ESC functions.
Real-World Cases
BYD DTC AI Analysis

Song Plus DM-i: IPB water ingress after wading caused left front inlet valve driver fault

✓
After wading through water, the dashboard displayed 'Check ABS System'. The scan tool retrieved DTC C001000 (active fault). Inspection found the IPB mounted low; splashing during the wade compromised the IPB wiring harness connector seal and allowed water ingress. Opening the connector revealed green oxidised pins. Cleaned the connector with electronic cleaner, dried it, reapplied conductive grease, and ensured the sealing ring seated properly. Cleared the DTC and monitored for one week; the fault did not recur.
BYD DTC AI Analysis

Replaced IPB assembly due to open circuit in internal solenoid coil.

✓
2021 Song PLUS DMi at 30,000 km, ABS warning light illuminated while driving. Diagnosis showed C001000 static fault. Removed IPB assembly, disconnected electro-hydraulic module from ECU, and measured left front inlet valve coil pin directly. Resistance read infinite (normal: 4.5Ω), indicating open circuit in valve body internal coil. As IPB is highly integrated, replaced IPB electro-hydraulic module assembly. Performed bleed procedure and ESC calibration; fault resolved.
BYD DTC AI Analysis

Contaminated brake fluid caused the valve to stick, triggering a false warning.

✓
Vehicle set C001000 one week after an unauthorised shop replaced the brake fluid with inferior product. Inspection found the fluid cloudy and milky white (severely water-contaminated). The inferior fluid corroded and seized the inlet valve spool; the ECU detected abnormal drive current (excessive draw or response timeout) and logged the fault. Replaced the IPB electro-hydraulic module (internally contaminated), thoroughly flushed all brake lines, replaced all brake hoses and wheel cylinders, then refilled with DOT4 fluid and bled the system.
BYD DTC AI Analysis

Intermittent fault caused by software calibration error

✓
Intermittent C001000 fault code found during new vehicle delivery PDI. No abnormal braking feel. Checked wiring harness and valve body resistance – both normal. Consulted technical bulletin: this batch of IPB software has overly strict solenoid drive diagnostic thresholds. Upgraded IPB ECU software to latest version (V2.1 or above). Fault code no longer appears after upgrade; no hardware replacement required.
BYD DTC AI Analysis

False fault caused by poor IPB ground

✓
After accident repairs, the vehicle set DTC C001000 and multiple IPB-related fault codes. Inspection found the IPB ground bolt loose from the collision repair, causing high ground resistance (measured 2.3Ω; spec <0.1Ω). The poor ground dropped solenoid drive voltage, causing the ECU to flag a false drive-circuit fault. Sanded the ground terminal, tightened the bolt to spec (8–10Nm), and cleared the fault.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.