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C000100

DTC C000100 indicates an electrical or mechanical fault in TCS (Traction Control System) Control Valve A inside the IPB (Integrated Power Brake) — Seal 6 EV

Braking System

DTC C000100 indicates an electrical or mechanical fault in TCS (Traction Control System) Control Valve A inside the IPB (Integrated Power Brake).

In BYD e-Platform 3.0 and DM-i architectures, the IPB module integrates the ABS/ESP/TCS hydraulic unit and ECU into a single assembly.

Valve A is typically the TCS main control solenoid valve or the left front wheel changeover valve.

This fault occurs when the ECU detects an abnormal valve drive circuit (open circuit, short circuit, or overcurrent) or an abnormal valve spool position feedback signal (delayed response or sticking).

When triggered, the fault disables the TCS function and forces the vehicle into fail-safe mode.

The system may limit ABS function but typically retains basic hydraulic braking (unassisted or partially assisted).

Due to the integrated design of the hydraulic oil circuit and solenoid valve inside the IPB assembly, technicians typically replace rather than repair this component.

The C000100 fault code on the Seal 6 EV indicates a medium-severity electrical or mechanical fault in TCS Control Valve A within the Integrated Power Brake module. Common causes include an internal solenoid valve coil open/short circuit or a sticking valve spool due to contaminated or aged brake fluid. Traction control may be disabled, but basic braking usually remains. Visit an authorised dealer; IPB replacement is often required. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1IPB module internal solenoid valve coil fault: open circuit, short circuit, or resistance drift (normal range is typically 20-60Ω, depending on specific model), causing abnormal drive circuit detection.
  • 2Valve spool mechanical binding: Prolonged failure to replace brake fluid causes impurity buildup and poor valve spool lubrication, or abnormal brake fluid viscosity at low temperatures causes sluggish valve spool operation.
  • 3Control circuit board fault: Overheating damage to the solenoid valve driver chip (MOSFET or dedicated driver IC) on the IPB internal PCB, or poor or broken solder joints.
  • 4Wiring harness and connector issues: Poor sealing of the IPB assembly connector (usually located on the top or side of the module) causes terminal oxidation or back-out, or a chassis impact breaks the internal wiring harness.
  • 5Brake fluid degradation: Excessive water content (>3%) corrodes internal metal components of the solenoid valve, or using non-DOT4 brake fluid causes seals to swell and bind.
What To Do
  • 1
    Initial diagnosis: Use the BYD VDS diagnostic tool (VDS2000/3000) to read all fault codes. Check for accompanying code C000104 (circuit control valve 1 fault), U-prefix communication faults, or other wheel speed sensor faults. Record the vehicle speed, brake pedal status, and hydraulic pressure values from the freeze frame data.
  • 2
    Visual and wiring inspection: Disconnect the battery negative terminal. Check the IPB module for brake fluid leakage (especially at the junction between the motor and valve body). Measure the voltage of the IPB connector power pins (constant power, ignition power), ground pins, and CAN lines (CAN-H 2.5-3.5V, CAN-L 1.5-2.5V). Check the Valve A drive circuit resistance for abnormalities.
  • 3
    Active test and functional verification: Connect the diagnostic tool and perform the 'solenoid valve actuation test'. Listen for the actuation 'click' from TCS valve A. Compare the sound with other valves. No sound or a faint sound indicates the valve is not actuating. Use an oscilloscope to observe the drive current waveform. The normal waveform is a square-wave pulse. A current of 0 or a continuous high level confirms a circuit fault.
  • 4
    Hydraulic system check: Check the brake fluid level and colour. Test using a brake fluid moisture tester. If the moisture content is >3% or the colour is cloudy, completely replace with DOT4 brake fluid and perform the IPB bleeding procedure (execute 'Hydraulic Unit Bleeding' mode using the diagnostic tool).
  • 5
    Assembly replacement and matching: If diagnostics confirm an internal IPB fault, replace the IPB electro-hydraulic module assembly with ECU (match the spare part number to the vehicle configuration). After installation, perform: ① Coding configuration; ② Longitudinal/lateral acceleration sensor calibration; ③ Wheel speed sensor signal verification; ④ Road test to verify TCS function (test start-off slip control on a low-adhesion surface, such as wet tiles).
  • 6
    Repair confirmation: Clear the fault code and perform a road test of at least 5 km in mixed driving conditions, including low-speed braking, emergency braking, and cornering. Read the fault codes again. Confirm C000100 does not recur and the instrument cluster ESC/TCS warning light is off.
Real-World Cases
BYD DTC AI Analysis

2021 Song PLUS DM-i: TCS light on with hard brake pedal

✓
The vehicle had covered 30,000 km when the ESC and TCS warning lights illuminated constantly on the dashboard. Diagnostic scan retrieved DTCs C000100 (TCS Control Valve A Fault 1) and C000104 (Circuit Control Valve 1 Fault). Inspection revealed slight leakage at the IPB module connector, with green corrosion on pins 3 and 4 (valve A drive). Cleaned the connector and applied conductive grease, which temporarily cleared the fault, but it returned after three days. Disassembled the IPB and found overheating damage to the internal PCB driver chip. Replaced the IPB assembly and completely replaced the brake fluid to resolve the issue. Root cause was micro-leakage of brake fluid causing circuit corrosion.
BYD DTC AI Analysis

Han EV Genesis Edition: Intermittent brake system fault at low speeds

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ABS warning light illuminated intermittently at 20–40 km/h. Scan tool retrieved history DTC C000100. During static testing, valve A actuation sound was intermittent. Valve A coil resistance measured 45 Ω at ambient temperature (normal), but rose to 120 Ω after heating to 60 °C with a heat gun (thermal open circuit). Diagnosed as internal IPB solenoid coil thermal stability failure. As the IPB is a complete assembly, replaced the unit and performed sensor calibration and brake bleeding. Fault has not reoccurred.
BYD DTC AI Analysis

Tang DM-p TCS failure after off-roading

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After an off-road water crossing, the dashboard displayed "Check brake system" with DTC C000100. Inspection revealed mud and water splash marks at the IPB mounting location (left front chassis rail) and a deteriorated connector seal. Further testing found TCS valve A spool sticking, likely from sand and silt entering the valve body through the breather or contaminated brake fluid. Cleaning the IPB and replacing the brake fluid did not resolve the issue; replaced the IPB assembly. Advised the owner to regularly inspect the IPB connector seals and avoid direct high-pressure washing.
BYD DTC AI Analysis

New BYD Seal reported C000100 fault immediately upon delivery.

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During new vehicle PDI, the ESC warning light was on continuously with DTC C000100. The IPB wiring harness had been pinched during assembly, damaging the valve A drive wire insulation and causing a short to ground. Repaired the harness, secured the routing, cleared the fault code and repeatedly tested the TCS active intervention function – all normal. Assembly process issue; did not replace the IPB assembly.
BYD DTC AI Analysis

BYD Qin PLUS DM-i reported valve fault after brake fluid replacement

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DTC C000100 appeared after a brake fluid change at a non-authorised workshop. Inspection found the technician did not use a diagnostic tool to perform the IPB bleed procedure, instead bleeding manually by pumping the pedal. This allowed air into the valve body and caused valve A to stick due to an air lock. Ran the 'Hydraulic Unit Bleed' function on the VDS (automatically cycles solenoid valves to build pressure and bleed). Repeated three times. Fault code cleared automatically and function returned to normal.
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.