AU
C001C00

DTC C001C00 indicates the IPB (Intelligent Integrated Braking System) ECU detects a fault in the right rear wheel inlet valve (normally open valve) drive circuit — Seal 6 EV

Braking System

DTC C001C00 indicates the IPB (Intelligent Integrated Braking System) ECU detects a fault in the right rear wheel inlet valve (normally open valve) drive circuit.

This typically occurs when the internal ECU valve drive circuit (MOSFET or dedicated driver chip) detects an open circuit, short to power, short to ground, or abnormal current feedback while attempting to drive the right rear inlet valve.

The inlet valve acts as a key actuator in the ABS/ESP hydraulic control unit, controlling brake fluid flow from the master cylinder to the right rear wheel cylinder.

This fault prevents the right rear wheel from participating in ABS pressure regulation and ESP active braking intervention.

Extreme cases may affect braking balance; however, the system retains basic hydraulic braking functions (direct pedal pressure build-up).

The warning lamp illuminates, and the system disables functions including ABS, ESP, and Automatic Emergency Braking (AEB).

The C001C00 fault code on the Seal 6 EV indicates a medium-severity fault in the IPB braking ECU’s right rear wheel inlet valve drive circuit. This can disable ABS, ESP, and AEB, though basic hydraulic braking should remain. Common causes include an open or shorted inlet valve coil or a failed internal ECU driver chip/MOSFET. Visit an authorised dealer for diagnosis and repair. Real cases exist, so typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Open or short circuit in the right rear inlet solenoid valve coil inside the IPB electro-hydraulic module (resistance outside the standard 3-7Ω range)
  • 2Hardware fault in the IPB ECU internal valve drive circuit, such as a damaged driver chip (e.g., L9369 or other dedicated IC) or MOSFET breakdown.
  • 3IPB wiring harness connector (usually located on the top or side of the module) is loose, corroded by water ingress, or has oxidized pins, causing excessive contact resistance.
  • 4Prolonged failure to replace the brake fluid causes contamination and deterioration, leading to mechanical binding of the inlet valve spool. The resulting abnormal drive current triggers fault protection.
  • 5Unstable IPB module power supply voltage or poor ground connection causes the ECU to misjudge the valve drive status.
What To Do
  • 1
    Use a dedicated diagnostic tool (VDS or equivalent) to read the complete fault codes and freeze frame data. Check for accompanying sub-codes such as C001C01 (right rear inlet valve short to power) or C001C02 (short to ground), and verify the hydraulic unit version number.
  • 2
    Visually inspect the exterior of the IPB electro-hydraulic module for leaks. Disconnect the battery negative terminal, then check if the connector pins are corroded, bent, or backed out. Measure the wiring harness continuity from the connector to the ECU.
  • 3
    Disconnect the IPB connector and use a multimeter to measure the right rear inlet valve solenoid resistance (typically the terminal corresponding to pin RR-INLET). The standard value is 3-7Ω. Compare this reading with the left rear wheel circuit resistance (corresponding to C001800). A deviation exceeding 2Ω indicates a faulty valve body.
  • 4
    Connect the diagnostic tool and perform the 'Hydraulic Unit Actuator Test'. Listen for the operating sound of the right rear inlet valve. If other valves click but the right rear valve is silent, or if the drive current exceeds 1.5A or falls below 0.3A, confirm an internal fault.
  • 5
    If diagnostics confirm an internal IPB fault, replace the entire IPB electro-hydraulic module assembly (the BYD part number varies by model; for example, the Song PLUS DM-i typically requires an assembly with an ECU). Never disassemble or repair the hydraulic unit separately.
  • 6
    After installing the new IPB, use the diagnostic tool to execute the 'Bleeding Procedure' (access IPB special functions to perform Motor Pump Bleeding and Wheel Cylinder Bleeding). Bleed the system in this sequence: right rear, left rear, right front, left front. Verify the lines are free of trapped air.
  • 7
    Clear all fault codes and perform a road test to verify: at speeds exceeding 40 km/h, apply emergency braking to test ABS operation, check the ESP OFF switch function, and confirm no warning lights illuminate on the instrument cluster.
Real-World Cases
BYD DTC AI Analysis

Open circuit in IPB internal solenoid valve coil caused ABS failure

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A 2021 Song PLUS DM-i at 30,000 km had constant ABS and ESP warning lights. VDS read fault code C001C00 (right rear inlet valve driver fault). Freeze frame showed 0 km/h vehicle speed at the time of the fault. The technician disconnected the IPB connector and measured the right rear inlet valve resistance at infinite (open circuit). The left rear inlet valve measured 5.2Ω (normal). This confirmed an open solenoid coil inside the IPB assembly. Replaced the IPB electro-hydraulic module assembly and performed the brake bleed procedure. Cleared the fault codes. ABS function returned to normal.
Original source ↗
BYD DTC AI Analysis

Connector corrosion after water ingress caused intermittent fault

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After driving through standing water, the dashboard intermittently displayed "Check Brake System" and DTC C001C00 set sporadically. The IPB wiring harness connector showed obvious water stains and green corrosion inside. Reduced insulation resistance between pins caused the ECU to misdiagnose an actuator fault. Cleaned the connector with electrical contact cleaner, dried it thoroughly, applied BYD conductive grease (or petroleum jelly), and repositioned the waterproof seal. No recurrence after one week of continuous monitoring following reassembly.
BYD DTC AI Analysis

Brake fluid contamination caused valve body sticking and false fault codes

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During maintenance, found severely degraded brake fluid (black, water content >4%). ABS warning light then lit up. Read DTC C001C00. Solenoid resistance measured normal, but actuation test showed drive current fluctuating abnormally (0.8A-1.2A unstable; normal is stable ~1.0A). Disassembled IPB for inspection (teaching demo) and found brown deposits jamming the inlet valve spool. IPB is a sealed assembly, so replaced the IPB module and brake fluid. Fault resolved. Advised owner to replace brake fluid every 2 years or 40,000 km.
Other Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.