AU
P25C700

This DTC indicates the brake booster (BLM/Booster) temperature sensor signal circuit voltage in the IPB (Intelligent Integrated Braking System) exceeds the normal range (0 — Atto 3

Braking System

This DTC indicates the brake booster (BLM/Booster) temperature sensor signal circuit voltage in the IPB (Intelligent Integrated Braking System) exceeds the normal range (0.5-4.5V).

The ECU detects a voltage signal continuously exceeding the threshold (typically >4.8V).

This condition usually indicates the temperature sensor signal wire shorts to the 12V power supply line (B+), or the internal thermistor fails due to a short circuit.

Due to temperature monitoring failure, the IPB enters a safety degraded mode and limits the brake assist function.

This limitation may cause a hard brake pedal and extended braking distance, constituting a severe fault that affects driving safety.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1The engine compartment wiring harness chafes against body metal or sharp edges, damaging the temperature sensor signal wire insulation and shorting it to the 12V power wire.
  • 2Short circuit in the brake booster internal temperature sensor thermistor, abnormally pulling the signal voltage up to the 5V reference voltage.
  • 3Water ingress, submersion, or moisture corrosion at the IPB wiring harness connector (usually located near the front compartment bulkhead) creates a low-resistance path between the signal and power terminals.
  • 4IPB control unit internal signal sampling circuit fault (damaged ADC module or abnormal reference voltage), causing false overvoltage detection.
  • 5Wiring harness connector terminals backed out, deformed, or incorrectly pinned during repair, causing a short circuit between the signal wire and the power wire.
What To Do
  • 1
    Use the VDS diagnostic tool to read all fault codes and freeze frame data. Record the voltage, temperature, and vehicle status when the fault occurred. Confirm DTC P25C700 is current and cannot be cleared.
  • 2
    Open the hood and visually inspect the wiring harness routing between the IPB and the Vehicle Control Unit (VCU). Focus on the firewall pass-through, harness retaining clips, and areas where the harness contacts metal brackets for signs of abrasion, damaged insulation, or burn marks.
  • 3
    Disconnect the IPB wiring harness connector. Use a multimeter to measure the temperature sensor signal wire resistance to ground and insulation resistance to power (B+). Normal resistance is >10MΩ. Low resistance indicates a short circuit.
  • 4
    At an ambient temperature of 20°C, measure the resistance between the two temperature sensor terminals. The normal range is 2-3 kΩ (NTC thermistor characteristic). If the resistance is <1 kΩ or close to 0 Ω, the sensor is internally shorted.
  • 5
    Inspect the connector terminals for signs of water ingress, green oxidation, and pin corrosion or deformation. Clean with electrical contact cleaner and apply conductive grease. Replace the connector or terminals if necessary.
  • 6
    If the wiring harness and sensor are normal, measure the voltage to ground at the IPB module connector signal input terminal. If it still reads the 5V reference voltage, the IPB internal sampling circuit has failed. Replace the IPB electro-hydraulic brake assembly.
  • 7
    After replacing the IPB assembly or repairing the wiring harness, perform the complete brake system bleeding procedure, brake pedal position sensor zero-point calibration, and ESC system initialization learning.
  • 8
    Clear the fault code and perform static and dynamic road tests (including hard acceleration and emergency braking) to verify the fault does not recur and the brake system functions normally.
Real-World Cases
BYD DTC AI Analysis

Wiring harness chafing caused short to power (Seal 6 DM-i)

✓
A Seal 6 DM-i with approximately 20,000 km on the clock suddenly displayed a "Brake System Fault" warning while driving, and the brake pedal went stiff. VDS read code P25C700. Inspection found the IPB-to-VCU harness rubbing against a metal edge at the firewall in the engine bay. Chafed insulation allowed the temperature sensor signal wire to short to the 12V power supply, spiking the signal voltage to 5.1V. Repair: Cut out the damaged harness section, re-soldered the wires and insulated them with heat-shrink tubing, adjusted the harness routing and added protective sleeving, and replaced the damaged connector terminals. Cleared the code after repair; brake system returned to normal.
Original source ↗
BYD DTC AI Analysis

Sensor internal thermistor short circuit (Song Plus DM-i)

✓
A Song PLUS DM-i intermittently logged P25C700 during cold starts; the cluster displayed "Check Brake System". The fault cleared when warm but recurred. Freeze frame data showed the temperature sensor at 5.1V during the fault. Unplugged the IPB connector and measured sensor resistance: 0.5kΩ at 20°C ambient (normal: 2-3kΩ). Diagnosed as a shorted brake booster internal temperature sensor thermistor. Since the sensor isn't available separately, replaced the electronic brake booster (iBooster) assembly. Bled the brake system and calibrated pedal position; fault resolved.
Original source ↗
BYD DTC AI Analysis

Water ingress corroded connector, causing short circuit (Han EV)

✓
A Han EV displayed a brake system fault on the instrument cluster the day after driving through water, logging DTCs P25C700 and U01F087 (communication timeout). Inspection revealed significant water staining and green copper corrosion inside the IPB wiring harness connector in the front compartment. Electrolytic corrosion between the temperature sensor signal terminal and the 12V power terminal created a low-resistance path measuring only tens of ohms. Solution: Thoroughly cleaned the connector pins with electronic cleaner and rust remover, removed the oxidation layer, then applied conductive grease and silicone-based sealant for waterproofing. Inspected and replaced the wiring harness seal. Cleared the fault codes and performed a dynamic test after the repair; the fault did not recur.
Original source ↗
BYD DTC AI Analysis

IPB module internal sampling circuit fault (Tang DM-p)

✓
A Tang DM-p repeatedly set DTC P25C700. External harness insulation measured normal, sensor resistance was within range (2.5kΩ), and the signal wire showed no short-to-power. Further testing revealed the signal voltage at the IPB module connector remained at the 5V reference, indicating internal ADC sampling circuit damage or reference voltage regulator failure in the IPB control unit. Replaced the IPB electro-hydraulic module assembly with integrated ECU, completed system calibration and brake bleeding. DTC cleared and brake assist function returned to normal.
BYD DTC AI Analysis

Wiring harness connector pins misaligned after repair (Qin PLUS EV)

✓
A Qin PLUS EV set code P25C700 on startup after other front-compartment repairs. Inspection found the IPB harness connector forced in without full alignment during the prior work, shorting the temperature sensor signal terminal (Pin 4) to the 12V power terminal (Pin 1) inside the connector. Fix: Disconnected the connector, checked terminal positions, and found the signal terminal had backed out with metal deformation. Corrected the terminal position with a special tool, replaced the damaged terminal housing, then aligned and securely reconnected the connector. Fault cleared.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.