AU
C002400

DTC C002400 indicates the IPB (Integrated Electro-Hydraulic Braking) system detects an electrical fault in the brake pedal pressure feedback signal circuit — Seal U

Braking System

DTC C002400 indicates the IPB (Integrated Electro-Hydraulic Braking) system detects an electrical fault in the brake pedal pressure feedback signal circuit.

The IPB system uses the brake pedal travel sensor (or pressure sensor) to monitor the driver's braking intent in real time.

This sensor typically mounts on the brake pedal mechanism or master cylinder input and provides an analog voltage or PWM signal to the IPB ECU.

The ECU triggers this DTC when it detects an open circuit, a short to ground or power in the signal circuit, a signal voltage outside the calibrated range (e.g., 0.5-4.5V), or an abnormal signal drift rate.

This fault limits or disables the brake assist function, deactivates the ESC/ABS system, and disables the Automatic Emergency Braking (AEB) function.

The vehicle may enter mechanical backup braking mode, which significantly increases pedal effort and severely compromises driving safety.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Brake pedal travel/pressure sensor internal coil open circuit, Hall element failure, or signal drift
  • 2Sensor wiring harness worn, open, or shorted to ground at the pedal mechanism, firewall pass-through, or high-temperature area in the motor compartment.
  • 3Fault in the internal signal acquisition circuit, ADC conversion circuit, or power supply circuit of the IPB electro-hydraulic module
  • 4Sensor connector water ingress and oxidation, pin push-back, or poor contact (common after wading or washing the vehicle)
  • 5Mechanical binding or incomplete return of the brake pedal mechanism causes abnormal stress on the sensor or forces it out of range.
What To Do
  • 1
    Use the BYD VDS or Launch X-431 diagnostic tool to read the fault code. Confirm if C002400 is a current (active) or history fault. Record the pedal signal voltage value from the freeze frame data.
  • 2
    Visually inspect the brake pedal mechanism for smooth movement. Inspect the sensor body and wiring harness for damage or crush marks, focusing on the wiring harness sleeve between the pedal arm and the firewall.
  • 3
    Disconnect the sensor and IPB module connectors. Use a multimeter to measure circuit continuity (Sensor-IPB), insulation resistance to ground, and short circuit to power. Standard continuity resistance must be less than 1 Ω, and insulation resistance must be greater than 10 MΩ.
  • 4
    Connect the connector and measure the sensor supply voltage (typically 5V±0.25V or 12V). Simultaneously measure the signal output voltage. It must change linearly with pedal travel (0.5-4.5V range) without jumps or dead zones.
  • 5
    Check the pedal signal pins in the IPB module 32-pin or 48-pin connector for recession, oxidation, or deformation. Repair using a special tool if necessary.
  • 6
    If circuit measurements are normal but the fault persists, replace the brake pedal travel/pressure sensor (note: some models require replacing the pedal mechanism assembly together with the sensor). After replacement, perform brake pedal zero-point calibration.
  • 7
    If replacing the sensor does not resolve the fault, the IPB assembly has an internal fault. Replace the IPB electro-hydraulic module, then perform brake system bleeding, pedal calibration, and an ESC function test.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i pedal sensor wiring harness fatigue fracture

✓
At 80,000 km, the ABS/ESC warning lights illuminated intermittently with DTC C002400, often triggered on rough roads. Inspection found the wiring harness between the brake pedal and firewall had partially fractured internal copper strands from prolonged flexing during pedal operation, interrupting the signal. Replaced the pedal sensor with harness assembly, rerouted the wiring, and added securing cable ties to eliminate harness strain during pedal movement. Fault eliminated.
BYD DTC AI Analysis

Han EV IPB module internal signal acquisition circuit damaged

✓
Vehicle would not enter READY mode; the instrument cluster showed “Brake System Fault.” DTC C002400 was present and would not clear. Brake pedal sensor supply voltage measured 5 V (normal). Signal line voltage stayed at 0 V regardless of pedal position. Disconnected the sensor and measured signal line resistance to ground—normal, ruling out a short to ground. Internal signal acquisition circuit in the IPB module failed. Replaced the IPB assembly, filled brake fluid, bled the system, and calibrated the pedal zero-point. Fault cleared.
BYD DTC AI Analysis

Qin PLUS DM-i sensor connector oxidised due to water ingress

✓
After fording water approximately 30 cm deep, the instrument cluster brake system warning light stayed on constantly. The brake pedal felt normal, but AEB failed. Read DTC C002400. Found noticeable water inside the IPB-to-pedal sensor connector beneath the left front A-pillar; copper pins were oxidized and blackened. Cleaned the connector thoroughly with electronic cleaner, applied conductive grease, and dried it. Reconnected the connector, cleared the fault code, and restored system function.
BYD DTC AI Analysis

Tang DM-i pedal mechanism sticking caused sensor out-of-range

✓
Owner reported slow brake pedal return and intermittent 'Check brake system' warnings when parking, DTC C002400. Found the brake pedal pivot lacked lubrication and had severe dust buildup, causing the return spring to bind; the sensor detected abnormal pressure hold times and signal curves. Thoroughly cleaned the pedal mechanism, applied low-temperature grease, replaced the pedal pressure sensor that was internally damaged from long-term overload, and performed calibration. The fault did not recur.
BYD DTC AI Analysis

Voltage drop in power supply circuit causes abnormal signal — BYD Song Pro EV

✓
Instrument cluster showed intermittent brake system warning light with DTC C002400. Scan tool indicated pedal signal voltage occasionally dropped below 0.8V (normal idle ~1.2V). Sensor supply voltage measured at only 3.2V (spec 5V). Traced to poor contact at IPB module power output terminal causing voltage drop. Repaired IPB connector power pins, restoring stable 5V reference output. Fault resolved.
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.