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 — Seal U

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.

The P25C700 fault code on the Seal U indicates the brake booster temperature sensor signal voltage is too high, causing the braking system to enter a reduced-assist safety mode. This is a high-severity fault that may cause a hard brake pedal and longer stopping distances. Common causes include damaged wiring shorting to 12V or an internal sensor short. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1The engine compartment wiring harness chafes against body metal edges or sharp edges, damaging the temperature sensor signal wire insulation and causing a short circuit to the 12V power wire.
  • 2A short circuit in the brake booster internal temperature sensor thermistor pulls the signal voltage abnormally high 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 terminal and the power terminal.
  • 4IPB control unit internal signal sampling circuit fault (damaged ADC module or abnormal reference voltage), causing a false overvoltage report.
  • 5Backed-out or deformed wiring harness connector terminals, or incorrect pin placement 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 the complete fault codes and freeze frame data. Record the voltage, temperature, and vehicle status when the fault occurred. Confirm DTC P25C700 is currently present and will not clear.
  • 2
    Open the engine compartment and visually inspect the wiring harness routing between the IPB and the Vehicle Control Unit (VCU). Inspect the firewall pass-through, harness retaining clips, and metal bracket contact points for wear, insulation damage, 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 the power supply (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). A resistance of <1 kΩ or close to 0 Ω indicates an internal sensor short circuit.
  • 5
    Inspect the connector terminals for signs of water ingress, oxidation, and pin corrosion or deformation. Clean with electronic 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 signal input terminal of the IPB module connector. If the reading still shows a 5V reference voltage, the IPB internal sampling circuit is faulty. 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 rapid acceleration and emergency braking conditions) to confirm 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 Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.