AU
C007204

DTC C007204 indicates the standard solenoid valve (typically the inlet or outlet valve) inside the ABS/ESC Hydraulic Electronic Unit (HEU) triggered the overheat protection mechanism — Seal U

Braking System

DTC C007204 indicates the standard solenoid valve (typically the inlet or outlet valve) inside the ABS/ESC Hydraulic Electronic Unit (HEU) triggered the overheat protection mechanism.

The control unit detected the valve body temperature exceeded the safe threshold (typically >120°C) and entered protection mode to prevent valve spool binding or coil burnout.

Root causes include: 1) Actual overheating (continuous heavy braking, brake drag, or increased movement resistance from degraded brake fluid); 2) False overheat detection (abnormal valve coil resistance, control unit temperature monitoring circuit failure, or software algorithm error).

This fault limits or disables ABS/ESC functions, retaining only basic hydraulic braking.

This severely compromises braking safety and requires immediate repair.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Short circuit, open circuit, or resistance drift in the internal solenoid valve coil of the ABS hydraulic modulator, causing abnormal current and overheating.
  • 2Continuous heavy braking conditions (such as frequent braking on long descents) cause actual valve body overheating, exceeding its heat dissipation capacity.
  • 3Degraded brake fluid, excessive moisture content, or incorrect fluid type (non-DOT4) increases valve spool movement resistance and generates additional heat.
  • 4ABS control unit (ECU) internal temperature monitoring circuit fault, or software version defect causing false overtemperature indication
  • 5Mechanical drag in the brake system (poor caliper piston return, parking mechanism not fully released) generates continuous frictional heat that conducts to the hydraulic unit.
What To Do
  • 1
    Use a dedicated diagnostic tool (such as VDS2000/Launch PAD) to read all fault codes and freeze frame data. Verify if C007204 is a current fault. Record the vehicle speed, brake pressure, ambient temperature, and other parameters present when the fault triggered.
  • 2
    Verify the brake fluid level is between MAX and MIN. Check the brake fluid moisture content (should be <3%) and fluid type (must be DOT4). If necessary, completely replace the brake fluid and bleed the system.
  • 3
    Check the ABS hydraulic modulator (located on the left side of the engine compartment) for leakage or burn marks. Check the connector for oxidation or looseness. Measure the solenoid valve coil resistance (normal range: 2.5-5.0 Ω; deviation >20% is abnormal).
  • 4
    Perform the hydraulic unit Actuation Test. Listen for a clear, even operating sound from each solenoid valve to check for sticking valve bodies. Simultaneously check the return of all four brake calipers to rule out mechanical drag.
  • 5
    If diagnostics confirm an internal hydraulic modulator fault or a false ECU report, replace the ABS hydraulic modulator assembly with ECU (e.g., part number 10248455-00). After replacement, perform: 1) standard hydraulic bleeding; 2) ECU coding; 3) wheel speed sensor signal calibration; 4) road test to verify ABS function.
Real-World Cases
BYD DTC AI Analysis

E5 False Brake Disc Overheat Warning Caused by Wheel Speed Signal Anomaly

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Symptom: Dashboard ABS/ESC warning lights on. DTC C007204 (brake disc overheating) stored. Infrared thermometer showed normal brake disc temperature (approx. 60°C). Diagnosis: Read data stream and found left rear wheel speed sensor signal jumping intermittently (0-255 km/h). The control unit misjudged this as brake drag causing that wheel to overheat. Checked the wheel speed sensor connector and found internal water ingress with oxidation. Found iron debris on the tone ring. Solution: Cleaned the tone ring and replaced the left rear wheel speed sensor. Cleared the DTCs and road-tested 30 km—no recurrence.
Original source ↗
BYD DTC AI Analysis

Frequent braking triggered actual ABS valve body overheat protection in E5

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Symptoms: After extended downhill driving (continuous braking for approximately 10 minutes), the instrument panel warned with DTC C007204 and the brake pedal became hard. Diagnosis: The fault code cleared after the vehicle cooled, but recurred with repeated aggressive driving. Freeze frame data showed brake pressure >15 MPa for extended periods with calculated valve body temperatures above 130°C. Inspection found the brake fluid was 4 years old and never changed; it was black with 5% moisture content. Repair: Replaced brake fluid with new DOT 4 and thoroughly bled the system. Advised the customer to avoid continuous braking on long downhills and to use B-mode regenerative braking to assist deceleration. Follow-up: No further faults reported after three months.
Original source ↗
BYD DTC AI Analysis

Similar fault reference: Haval H9 (ABS hydraulic unit internal failure)

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Symptoms: Dashboard displayed brake system fault and stored DTC C007204 (brake disc overheating). No actual brake overheating occurred; ambient temperature was only 25°C. Diagnosis: Ruled out brake drag and brake fluid issues. Measured hydraulic modulator valve body coil resistance. The right front inlet valve coil measured only 1.2Ω (specification 2.8Ω), indicating an internal short caused excessive current and heat. Repair: Replaced the ABS hydraulic modulator assembly with integrated ECU. Completed coding and matching; fault cleared. This case demonstrates that DTC C007204 across different models indicates faults in the hydraulic valve body or temperature monitoring circuit.
Original source ↗
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.