AU
C053F00

DTC C053F00 indicates an electrical circuit fault in Primary Pressure Sensor 1 within the IPB (Intelligent Integrated Braking System, One-Box brake-by-wire unit) — Seal U

Braking System

DTC C053F00 indicates an electrical circuit fault in Primary Pressure Sensor 1 within the IPB (Intelligent Integrated Braking System, One-Box brake-by-wire unit).

Specifically, the signal circuit, 5V supply circuit, or ground circuit has a short to ground, short to power, or open circuit.

This sensor is a core input component of the brake-by-wire system.

It monitors brake master cylinder hydraulic pressure or pedal simulator pressure in real time, providing critical data for brake assist, energy recovery, ESC vehicle stability, and AEB automatic emergency braking.

When this fault occurs, the IPB immediately enters limp-home mode, potentially causing a loss of brake assist, a hard brake pedal, and complete deactivation of ABS and ESC functions.

This severe fault compromises driving safety.

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1IPB wiring harness connector (32-pin or 48-pin plug) seal failure. Water ingress after driving through water or high-pressure washing causes pin corrosion and oxidation, resulting in intermittent short or open circuits.
  • 2Pressure sensor 1 internal circuit damage (typically integrated inside the IPB assembly; not serviceable separately), possibly due to overvoltage, overheating, or component aging.
  • 3Chassis bottoming out or a detached wiring harness retaining clip causing harness wear, resulting in a signal wire short to body ground or the 12V power wire.
  • 4IPB controller internal signal processing circuit fault (ECU hardware fault), preventing correct acquisition of sensor analog signals.
  • 5Overdue brake fluid replacement leads to excessive water content. The fluid leaks at the sensor mounting seat into the electrical connector, causing corrosion and short circuits.
What To Do
  • 1
    Safety preparation: Disconnect the low-voltage battery negative terminal, remove the high-voltage service disconnect (MSD), wait at least 5 minutes to ensure high-voltage capacitor discharge, and wear insulated gloves and safety goggles.
  • 2
    Visual inspection: Inspect the IPB assembly at the front compartment firewall. Check the wiring harness connector for looseness, backed-out pins, water stains, white corrosion, or signs of brake fluid leakage. Pay special attention to the integrity of the sealing ring.
  • 3
    Power supply and ground verification: Connect the diagnostic tool, turn the ignition switch to ON, enter the IPB system to read the data stream, and check the Pressure Sensor 1 voltage. Use a multimeter to measure the sensor supply pin voltage (typically a 5V reference voltage, range 4.8-5.2V) and ground resistance (must be less than 1Ω).
  • 4
    Circuit continuity and insulation test: Disconnect the IPB connector. Measure the continuity resistance of the Pressure Sensor 1 signal wire from the IPB connector terminal to the internal circuit (or sensor terminal) (must be less than 1Ω). Measure the insulation resistance of the signal wire to ground (must be greater than 10MΩ) and to the 12V power supply (must be greater than 10MΩ).
  • 5
    Sensor signal simulation: Use an oscilloscope or diagnostic tool to perform an active test. Observe if the Pressure Sensor 1 signal changes linearly with brake pedal application. If the signal remains at 0V, 5V, or out of range (e.g., 65535 kPa), this indicates an internal fault in the sensor or ECU.
  • 6
    Repair or replace: If the wiring harness is faulty, repair it and apply waterproof insulation. If the IPB internal sensor or ECU is faulty, replace the IPB assembly (retain the original brake hose and bracket). After replacement, use VDS2000/VDS3000 to perform IPB coding configuration.
  • 7
    System calibration and bleeding: Perform the brake system bleeding procedure (use the diagnostic tool to operate the motor pump for bleeding), perform the pressure sensor zero-point calibration and pedal travel calibration, and ensure no air remains.
  • 8
    Function verification: Clear the fault code and perform a road test. Verify the ABS, ESC, energy recovery, and automatic emergency braking functions return to normal, and confirm C053F00 does not recur.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i: Water ingress corroded IPB connector after wading

✓
After driving through water, the dashboard displayed a brake system fault. Read fault code C053F00. Inspection found water ingress and green corrosion inside the IPB harness connector (located near the left front chassis rail). Resistance between the power and signal pins of pressure sensor 1 measured only 200Ω (abnormal). Cleaned the connector thoroughly with electronic cleaner, dried it, applied conductive grease, and replaced the waterproof seal. Fault resolved. Check the front compartment seal and waterproofing at the IPB mounting location.
BYD DTC AI Analysis

Seal EV: Replaced IPB assembly to resolve internal sensor fault

✓
While driving, the ABS/ESC warning light suddenly illuminated, the brake pedal went hard, and DTC C053F00 set. Checked wiring harness, power supply (5V normal), and ground—all normal. No shorts or opens in the signal line. Oscilloscope showed sensor output stuck at 4.9V without changing with pedal movement (normal: 0.5–4.5V linear). Diagnosed as IPB internal pressure sensor 1 failure. Replaced the IPB assembly (part number 1314600-XX), performed coding and brake bleed calibration. Fault resolved.
BYD DTC AI Analysis

Yuan Plus chassis wiring harness wear caused intermittent short circuit

✓
Owner reported intermittent brake system warnings, easily triggered on rough roads. Scan tool retrieved stored DTC C053F00. Raised the vehicle and found the IPB-to-body harness transition had detached from its retaining clip at the firewall penetration. The harness had chafed against the steering rack boot, damaging the signal wire insulation and causing intermittent shorts to ground. Repaired the damaged harness with double-layer heat-shrink tubing, resecured the routing, and added corrugated tubing protection. The fault has not reoccurred.
BYD DTC AI Analysis

Qin PLUS DM-i software false positive fixed by reflash

✓
New vehicle set C053F00 during PDI. Checked wiring harness, sensor power supply and signal — all normal. IPB hardware was early revision. Suspected early software version had a bug in the pressure sensor signal filtering algorithm, causing intermittent false positives. Resolution: Upgraded IPB module software via VDS (V1.02 to V1.05). Cleared fault codes after upgrade. Road tested multiple times without recurrence. No hardware replacement required.
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.