AU
P25C600

DTC P25C600 indicates a short to ground in the BLM (Brake Load Module) temperature sensor signal wire inside the IPB (Integrated Power Brake) — Seal U

Braking System

DTC P25C600 indicates a short to ground in the BLM (Brake Load Module) temperature sensor signal wire inside the IPB (Integrated Power Brake).

In the BYD Song PLUS DM-i One-Box braking system, the BLM typically refers to the brake motor or brake fluid temperature monitoring unit.

When the ECU detects the temperature signal voltage remaining below the set threshold (near 0V), it identifies a signal wire short to vehicle ground.

This fault prevents the IPB from accurately monitoring key component temperatures.

To prevent system overheating or degraded braking performance, the ECU triggers a safety protection mode, disables or limits electro-hydraulic brake assist, and illuminates the ABS, ESC, and brake system warning lamps.

Because this fault affects a core braking safety function, the system classifies it as a Level 3 severe fault.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Chassis scraping or vibration wear damaged the insulation on the BLM temperature signal wire from the IPB to the body wiring harness, causing a short to the vehicle body metal.
  • 2Insulation failure of the IPB assembly internal temperature sensor or a cold solder joint on the PCB causes the signal wire to short to housing ground.
  • 3Water ingress or oxidation in engine compartment or chassis connectors (such as the BJG02 or IPB 32pin connector) causing a short to ground between pins.
  • 4During accident repairs or chassis maintenance, sharp edges cut an improperly secured wiring harness, or incorrect reinstallation pinches the harness and causes a short circuit.
  • 5NTC resistor package failure inside the temperature sensor body shorts the signal terminal to the sensor housing.
What To Do
  • 1
    Connect the VDS2000/VDS3000 diagnostic tool, read all fault codes and freeze frame data, confirm P25C600 is a current fault accompanied by an illuminated IPB-related warning lamp, and record environmental data such as vehicle speed and temperature at the time of the fault.
  • 2
    Raise the vehicle and visually inspect the IPB assembly (located on the left side of the front compartment bulkhead) and wiring harness. Inspect the wiring harness where it contacts sharp body edges and check for loose retaining clips. Check for obvious damage, water ingress, or burn marks.
  • 3
    Disconnect the IPB assembly 32-pin main connector and the BLM temperature sensor connector (if separately detachable). Use a multimeter to measure the resistance between the signal wire (refer to the wiring diagram for the specific pin) and body ground: if the resistance is less than 5Ω, this confirms a short to ground in the wiring harness; if the resistance is infinite, the fault is internal to the IPB.
  • 4
    Inspect the wiring in sections along its routing: check the firewall wiring grommet, the area near the front compartment fuse box, and the wiring harness inside the underbody shield. Focus on interference points with the exhaust pipe and brackets. Repair any damaged wiring harness (wrap with insulating tape or replace the harness section). Ensure sufficient clearance between the wiring harness and the vehicle body.
  • 5
    If wiring harness measurements are normal, check the connector terminals for backed-out pins, corrosion, or conductive foreign matter. Clean or replace the connector. If the connector is normal, measure the internal IPB temperature sensor resistance (NTC resistance is approximately 10kΩ-20kΩ at room temperature). If abnormal, replace the IPB assembly.
  • 6
    After repair, reconnect all connectors. Use the diagnostic tool to clear the fault codes. Execute the IPB system bleeding and calibration procedure (Brake System Bleeding & Calibration). Perform an IGN ON self-check to confirm no fault codes are present. Road test the vehicle to verify ABS/ESC functions are normal and the warning lamp is off.
Real-World Cases
BYD DTC AI Analysis

Incorrectly installed underbody shield caused wiring harness chafing and short circuit

✓
A 2021 Song PLUS DM-i with 30,000 km on the clock displayed a sudden "Braking System Fault" warning after the owner drove through water. Scanned DTCs P25C600 and C003F00. Raised the vehicle and found the IPB wiring harness clip below the right front wheel arch liner had detached, allowing the loom to chafe against a sharp edge on the chassis subframe until the insulation wore through. Water from the wading conducted current, shorting the BLM signal wire to ground. Repair: Cut out the damaged section and reconnected the harness with heat-shrink tubing, resecured the wiring to specification with additional corrugated tubing protection, and adjusted the underbody shield position to prevent pinching. Cleared the DTCs and all functions returned to normal.
BYD DTC AI Analysis

IPB internal temperature sensor failure

✓
2022 Song Pro DMi, no accident history. ESC warning light came on intermittently; scanner showed P25C600 history fault. External wiring harness checked multiple times — no damage. IPB connector terminal insulation to ground measured normal. Disassembled IPB assembly for further inspection (requires specialized equipment). Found internal BLM temperature monitoring module NTC resistor encapsulation cracked, pins contacting housing. IPB is a sealed safety-critical assembly, so replaced with new IPB electro-hydraulic module (part number HA2E-3555100). Performed system bleeding and online matching. Fault eliminated.
BYD DTC AI Analysis

Water entered the connector after accident repairs, causing a short circuit.

✓
One week after front collision repairs, a Song PLUS DMi displayed a brake system warning. The 32-pin IPB connector in the front compartment was not fully latched and had obvious water stains inside from washing. The BLM temperature signal pin (typically pin X) shorted to the adjacent ground pin due to conductive water film. Technicians thoroughly blow-dried the connector, cleaned terminal oxides with electronic cleaner, applied conductive protectant, properly reconnected it, and confirmed the latch locked. The fault cleared and did not recur over one month of follow-up.
BYD DTC AI Analysis

Aftermarket underbody protection installation pinched the wiring harness, causing a short circuit

✓
The owner took the vehicle to a non-authorized workshop for underbody coating without adequately masking the IPB wiring harness. The coating seeped into the harness corrugated tubing and cured, causing the wiring to harden and become brittle. Driving vibrations broke the hardened harness at the mounting bracket, exposing the BLM signal wire core which contacted the vehicle body. Technicians removed the foreign coating material, replaced the damaged harness section, rerouted the wiring and added rubber protective sleeves. They emphasized that modification work must follow BYD technical specifications.
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.