AU
C059592

The IPB (Intelligent Power Brake) system triggers this DTC when the internal power drive circuit of the Electrical Booster detects an abnormal power supply — Seal U

Braking System

The IPB (Intelligent Power Brake) system triggers this DTC when the internal power drive circuit of the Electrical Booster detects an abnormal power supply.

The IPB system integrates the conventional vacuum booster, ABS, ESP, and EPB into a single unit, and uses a motor-driven hydraulic system to generate brake assist.

DTC C059592 indicates the control module detects the booster motor supply voltage falls outside the normal threshold (typically 9-16V), or the internal DC-DC conversion circuit, power drive MOSFET, or power management chip operates abnormally.

This fault disables or limits the electric brake assist function and significantly stiffens the brake pedal (requiring over 200N of pedal force).

Simultaneously, the system triggers safety protection mechanisms, restricting ADAS functions such as Autonomous Emergency Braking (AEB) and Adaptive Cruise Control (ACC), severely compromising driving safety.

The C059592 fault code on the Seal U indicates an abnormal power supply in the IPB electric brake booster circuit. This is a medium severity issue because brake assist may be reduced or disabled, making the pedal much harder to press and limiting ADAS functions such as AEB or ACC. Common causes include a weak 12V battery, poor charging, loose fuses, connectors, or grounds. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Low-voltage power supply system fault: Increased internal resistance due to battery aging, insufficient generator charging, or a voltage regulator fault causes the voltage to drop below 9V during startup or high-current operating conditions.
  • 2Wiring connection fault: Poor contact at the IPB power supply circuit fuse (usually 30A or 40A), loose power connector, oxidized or backed-out pins, or loose ground points G06/G08 causing excessive circuit resistance.
  • 3IPB internal power supply module fault: Damaged internal DC-DC converter, short/open in the assist motor drive circuit, or thermal damage to PCB power components.
  • 4Brake booster motor internal fault: Motor winding short or open circuit causes abnormal current and triggers power supply protection.
  • 5Environmental factors: Poor heat dissipation at the IPB mounting location triggers thermal protection, or connector seal failure allows water ingress, causing internal circuit corrosion and short circuits.
What To Do
  • 1
    Use the VDS2000/VDS3000 diagnostic tool to read the complete fault codes and freeze frame data. Record key parameters when the fault occurred, such as vehicle speed, voltage, and pedal position. Check for accompanying related fault codes, such as C059500 and C058200.
  • 2
    Check the vehicle low-voltage power supply system: measure the battery static voltage (≥12.4V), cranking voltage (≥9.6V), and charging voltage (13.8–14.8V). Check the battery internal resistance and state of health (SOH).
  • 3
    Check the IPB power supply circuit: Check the IPB power supply fuse (usually F1/30A or F2/40A) and relay in the engine compartment fuse box. Measure the voltage at IPB connector terminals B01-1 (+BAT constant power) and B01-2 (+IG1 ignition power). Check the tightness of ground points G06 and G08 and the ground resistance (must be <1Ω).
  • 4
    Dynamic voltage test: Measure voltage fluctuation at the IPB connector during vehicle startup and assist motor operation. Confirm no momentary voltage drops or spikes.
  • 5
    Check the physical condition of the IPB: verify the IPB mounting bracket is secure, the cooling environment is adequate, the connector shows no water ingress or corrosion, and the sealing ring is intact.
  • 6
    Perform system bleeding: If the vehicle has a history of brake fluid replacement or brake line disconnection, run the IPB electric bleeding procedure to eliminate motor overload caused by air lock.
  • 7
    Software update and calibration: Update the IPB control program to the latest version. If the fault persists, replace the IPB assembly.
  • 8
    Calibration after replacement: After replacing the IPB, perform yaw rate sensor calibration, brake pedal position sensor zero-point learning, linear valve learning, and the brake line bleeding procedure.
Real-World Cases
BYD DTC AI Analysis

Loose power supply connection caused power assist failure in Seal 06 DM-i

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Dashboard showed brake system fault, ESP warning light illuminated, and brake pedal became hard. Scan tool read IPB system DTC C059592 (Electrical booster power supply abnormal). Found loose connection in IPB power supply fuse holder; voltage dropped to 8.2V under high current. Repaired fuse holder terminals and tightened power wiring harness connectors to clear the fault. One week later the fault returned. Further testing found intermittent open circuit in IPB internal power module. Replaced IPB assembly and performed calibration to resolve.
Original source ↗
BYD DTC AI Analysis

Excessive battery voltage drop during cold start triggered Han EV fault

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The owner reported occasional heavy brake pedal on cold starts, with the instrument cluster displaying "Check Brake System". The fault cleared after warmup. Retrieved historical DTC C059592. Testing revealed battery degradation (internal resistance 18mΩ, state of health 62%). Voltage dropped to 8.5V at startup, causing insufficient power to the IPB assist motor and triggering protection. Replaced the battery and tightened the IPB ground lead. Monitored cold starts for one week with no recurrence.
Original source ↗
BYD DTC AI Analysis

Song PLUS DM-i IPB poor heat dissipation causing intermittent fault

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While driving, the instrument cluster suddenly displayed a brake system fault. The ABS and ESP warning lights illuminated and brake pedal travel increased. Scanning revealed codes C059592 and C058200 (abnormal motor circuit signal). The fault occurred intermittently, returning after 50-100 km once cleared. Inspection showed the IPB mounted close to the turbocharger; a missing heat shield caused internal overheating of the control unit, activating thermal protection in the power module. Reinstalled the heat shield, cleaned the IPB connector and applied conductive grease. The fault has not recurred.
Original source ↗
BYD DTC AI Analysis

Qin PLUS DM-i brake booster motor internal short circuit

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The brake pedal gradually hardened until almost no assist remained, with the instrument panel showing continuous warnings. Retrieved DTC C059592. Measured IPB supply voltage at 12.8V (normal), but the scan tool showed abnormal booster motor current: peak exceeded 30A then suddenly dropped to zero. Disassembled the IPB and found partial short circuit in the brake booster motor windings, triggering internal drive circuit overload protection. Replaced the IPB integrated brake unit assembly, calibrated the yaw rate sensor, bled the brakes, and cleared the fault.
Original source ↗
BYD DTC AI Analysis

Water ingress corroded the Dolphin's IPB connector, causing abnormal power supply.

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Brake system fault after vehicle drove through water; dashboard displayed "Service Brake System". Found IPB connector seal damaged with water inside and green corrosion on pins. Cleaned and dried connector; fault temporarily cleared but returned after two days. Measured power pin contact resistance at 3.2Ω (normal <0.5Ω), causing voltage drop to booster motor under load. Replaced IPB wiring harness connector, cleaned ground point, and replaced IPB assembly (internal circuit corrosion). Fault fully resolved.
Original source ↗
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.