AU
C053E00

DTC C053E00 indicates a short to ground in the signal circuit of IPB (Intelligent Integrated Braking System) master cylinder pressure sensor 1 — Seal U

Braking System

DTC C053E00 indicates a short to ground in the signal circuit of IPB (Intelligent Integrated Braking System) master cylinder pressure sensor 1.

This sensor monitors brake master cylinder hydraulic pressure in real time and serves as the core feedback component of the brake-by-wire system.

The ECU uses this signal to calculate brake assist demand, trigger energy recovery, and control ABS/ESC intervention timing.

The ECU sets this fault when it detects the sensor signal voltage remaining continuously below the threshold (typically <0.5 V, normal range 0.5–4.5 V) or an abnormal drop in signal wire resistance to ground.

This fault causes abnormal brake pedal feel (too hard or too soft), degrades energy recovery, and forces the ESC/ABS system into a degraded mode (illuminating multiple instrument cluster warning lights).

Extreme cases may trigger limp-home mode (speed-limited driving).

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Physical damage to the wiring harness: Harness sheath wear, aging, or cracking in the high-temperature area of the engine compartment or near the steering mechanism causes the signal wire (usually 0.5-1.0 mm² wire) to contact metal body parts and short circuit.
  • 2Connector water ingress and corrosion: Seal failure at the 24-pin main connector on the IPB assembly or the sensor sub-connector. Water wading or high-pressure washing oxidizes the internal terminals, creating a low-resistance path between the signal terminal (pin) and the ground terminal.
  • 3Internal short circuit in the sensor body: Damage to the internal pressure-sensitive element or signal conditioning circuit of the master cylinder pressure sensor causes the output terminal to short to the housing/ground wire (internal insulation breakdown).
  • 4Internal IPB controller fault: RC filter capacitor breakdown or ESD protection diode short circuit in the control unit's internal signal sampling circuit causes the system to falsely detect an external circuit short to ground.
  • 5Improper repair: During accident repair or modification, improperly securing the wiring harness allows metal edges to pinch the harness, or loose insulation tape causes abrasion damage.
What To Do
  • 1
    Preliminary diagnosis: Use VDS2000/VDI to read all fault codes. Confirm if C053D00 (pressure out of range) or C053F00 (open circuit) is also present. Record freeze frame data (vehicle speed, brake pedal travel, and pressure value at the time of the fault).
  • 2
    Visual inspection: Focus on the transition area between the IPB assembly (located on the left side of the front compartment firewall) and the body wiring harness. Check the 24-pin grey connector for water ingress (look for green corrosion on the terminals). Inspect the wiring harness for abrasion where it passes through the firewall grommet.
  • 3
    Circuit measurement: Disconnect the IPB connector. Use a multimeter to measure the resistance between the signal wire (typically Pin 15, or refer to the specific pinout diagram) and ground. Normal resistance is >10MΩ. A reading <10Ω confirms a short circuit. Measure in sections to locate the short circuit (disconnect intermediate connectors and test each section individually).
  • 4
    Sensor body test: Disconnect the pressure sensor connector. Measure the resistance between the signal terminal and the ground terminal on the sensor side. If the resistance is <100Ω, replace the sensor. Simultaneously measure the signal wire resistance to ground on the wiring harness side to confirm the short circuit is in the wiring harness, not the sensor.
  • 5
    Insulation repair: After identifying wiring harness damage, strip the damaged section and re-insulate using heat-shrink tubing or waterproof tape. Adjust the wiring harness routing to avoid contact with sharp edges. If water enters the connector, clean it with electrical contact cleaner and spray WD-40 water repellent. Replace the connector terminals if necessary.
  • 6
    Function verification: After repair, clear the fault code. Execute the IPB system bleeding procedure (activate the motor pump using the diagnostic tool). Perform a brake pedal feel test and a road test. Confirm the pressure sensor signal changes linearly within the 0-16 MPa range, with no spikes or dropouts.
Real-World Cases
BYD DTC AI Analysis

Song Plus DM-i multiple system warnings after water ingress (C053E00+C053F00)

✓
A 2021 Song PLUS DM-i displayed simultaneous ABS, ESP and brake system warning lights after driving through standing water during heavy rain. Fault codes: C053E00 (Pressure Sensor 1 short to ground) and C053F00 (circuit open). Inspection revealed water inside the 24-pin connector below the IPB assembly. Electrolyte contamination had shorted Pin 15 (pressure sensor signal) to Pin 7 (ground). Repair: Removed the connector, cleaned the terminals with anhydrous ethanol, dried them with compressed air, applied conductive grease and reinstalled. A degraded connector seal caused the water ingress. Replaced the seal and cleared the fault. Total repair time: 2.5 hours.
BYD DTC AI Analysis

Wiring harness pinched during accident repair, causing intermittent short circuit

✓
Following front-end collision repairs, the vehicle developed intermittent brake pedal stiffness while driving and the ESC warning lamp illuminated. The diagnostic scanner showed history DTC C053E00. Inspection revealed that when securing the bulkhead harness, the repairer had clamped the IPB pressure sensor wiring against the edge of a metal bracket. Driving vibrations wore through the insulation, causing intermittent shorting between the signal wire and the bracket. Technicians rerouted the harness, wrapped the damaged section with foam tape, and repositioned the cable ties to eliminate stress concentration. This completely resolved the fault.
BYD DTC AI Analysis

IPB internal circuit failure caused false fault codes (sensor normal)

✓
2022 Song Pro DM-i repeatedly set C053E00. Replaced the pressure sensor and wiring harness, but the fault persisted. Disconnected the sensor and measured resistance from the IPB controller's internal signal sampling terminal to ground: only 50Ω. This confirms the filter capacitor in the controller's internal signal processing circuit has shorted. Replaced the IPB assembly (part number SC-3645100), completed system configuration and brake bleeding, and the fault cleared. Isolated IPB controller hardware defect; process as warranty claim.
BYD DTC AI Analysis

Water entered sensor connector, causing short circuit after high-pressure wash.

✓
After the owner used a high-pressure washer to clean the engine bay, the vehicle reported a brake system fault on startup (code C053E00). Inspection revealed the waterproof cover on the pressure sensor connector (located on top of the brake master cylinder) was not fully seated, allowing water to enter and short the signal terminals to ground. Repair: Disconnected the connector and allowed it to dry, cleaned it with precision electronics cleaner, measured insulation resistance until it returned to normal, then reset. Advised the owner to avoid directing high-pressure water at electrical components.
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.