AU
P060400

DTC P060400 indicates a read/write checksum error in the RAM (Random Access Memory) of the IPB (Integrated Power Brake) control unit — Seal U

Braking System

DTC P060400 indicates a read/write checksum error in the RAM (Random Access Memory) of the IPB (Integrated Power Brake) control unit.

This fault represents an ECU internal memory integrity self-test failure, indicating the IPB module detected abnormal data storage or retrieval in its internal working memory during the power-on self-test.

The IPB uses RAM as the critical storage medium during operation to store temporary variables, fault counters, system status flags, and real-time control parameters.

This fault forces the IPB into a degraded mode and may restrict or completely disable the ABS, ESP, Automatic Emergency Braking (AEB), and Electronic Parking Brake (EPB) functions, severely compromising vehicle active safety.

Simply clearing the code usually does not resolve this fault; it typically indicates substantial hardware damage or a severe firmware error.

The P060400 fault code on the Seal U indicates an internal RAM read/write checksum error in the Integrated Power Brake control unit. This is a medium-severity fault that can put braking support systems into degraded mode, affecting ABS, ESP, AEB, or EPB functions. Common causes include internal RAM hardware damage or unstable IPB power or ground supply. 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
  • 1Hardware damage or aging of the internal RAM chip in the IPB electro-hydraulic control unit. Semiconductor physical defects, electrostatic breakdown, or long-term thermal cycling stress typically cause the memory cells to fail.
  • 2Abnormal IPB ECU power supply system, including battery voltage fluctuation, unstable ignition power supply (IGN), or poor ground connection, causing bit flips or data loss in the RAM during read/write operations.
  • 3Defective or outdated IPB control software/firmware with memory management vulnerabilities or an overly sensitive RAM self-check algorithm, causing false faults or an actual memory leak that triggers hardware protection.
  • 4Moisture or water ingress inside the control unit, particularly due to poor sealing at the IPB installation position (motor compartment or cabin front bulkhead), causes PCB corrosion or pin-to-pin short circuits, compromising RAM signal integrity.
  • 5Strong electromagnetic interference (EMI) or transient overvoltage in the vehicle electrical system (such as during start-up, DC fast charger connection/disconnection, or starting/stopping high-power electrical components) causes RAM data corruption or abnormal latch status.
What To Do
  • 1
    Connect the BYD VDS2000/3000 diagnostic tool to the vehicle. Read the complete fault code stream. Confirm if P060400 is present and Active. Record environmental parameters such as voltage and temperature from the Freeze Frame data.
  • 2
    Execute the 'Clear DTCs' operation, perform an ignition cycle (OFF-ON-OFF), and check if the fault code reappears immediately. If the fault is intermittent, check the IPB supply voltage (constant B+ should be 12.5-14.5V, stable IGN power supply) and ground resistance (<0.5Ω). Use an oscilloscope to monitor for voltage drops.
  • 3
    Check the IPB software version and compare it with the BYD TPI (Technical Product Information) bulletin to confirm if a software upgrade procedure exists for P060400. If available, perform an IPB control unit software reflash or configuration reset.
  • 4
    Inspect the physical condition of the IPB. Disconnect the connector and inspect for water ingress, oxidation, and backed-out pins. Inspect the IPB housing for damage or signs of water ingress. Measure the internal insulation resistance using an insulation tester. If moisture is present, dry the affected area and apply electrical contact protectant.
  • 5
    If the above steps fail, diagnose an internal IPB hardware fault. Replace the IPB electro-hydraulic brake assembly (part numbers vary by vehicle model; e.g., 351XXX-XXXX for Song PLUS DM-i). After replacement, perform: ① brake line bleeding ② longitudinal acceleration sensor calibration ③ steering wheel angle sensor calibration ④ EPB function initialization ⑤ AEB/ACC sensor calibration (if equipped).
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i IPB Assembly Replacement Case

✓
A 2021 Song PLUS DM-i with 32,000 km arrived with ABS, ESP and EPB warning lights simultaneously illuminated on the instrument cluster. The owner reported normal brake pedal feel but automatic emergency braking inoperative. VDS scan retrieved intermittent codes P060400 (RAM Error) and U012100 (Lost Communication with IPB). IPB supply voltage checked normal. Cleared codes but they returned after 50 km driving. Disassembled IPB and found slight oxidation on internal PCB, diagnosing RAM chip hardware failure. Replaced IPB assembly with new unit, performed brake bleeding and all sensor calibration. Fault eliminated.
BYD DTC AI Analysis

Software update fixed RAM error on Han EV

✓
2022 Han EV Flagship. Intermittent brake system warning on instrument cluster at startup, DTC P060400. Checked power supply system—normal. No water ingress in IPB connector. Queried BYD TPI: this VIN belongs to a specific batch with a RAM self-test algorithm defect in IPB software. Upgraded IPB control unit software from V1.02 to V1.05, cleared fault codes. Monitored one month, no recurrence. Confirmed software false alarm, not hardware damage.
BYD DTC AI Analysis

Tang DM-i IPB Internal Short Circuit Repair After Driving Through Water

✓
A 2021 Tang DM-i displayed "Braking System Fault" after driving through water. Current fault code P060400 would not clear. Inspection showed the IPB mounted near the left front wheel arch. Water had entered the control unit through deteriorated seals during the crossing. Disassembly revealed electrolytic corrosion around the RAM chip and abnormal PCB impedance. The IPB is a sealed, non-serviceable assembly. The module was replaced with a new unit and the wiring harness waterproofing improved, clearing the fault.
BYD DTC AI Analysis

Seal overheated during extended high-speed driving, causing RAM error

✓
2023 BYD Seal AWD. Owner reported the instrument cluster showed a brake system fault after 2 hours of continuous high-speed driving (>140km/h). The warning light cleared after parking for 30 minutes. Diagnostic scanner retrieved historical DTC P060400. Analysis determined the IPB control unit had insufficient cooling, causing the RAM chip to operate unstably at high temperatures (>85°C). Inspection found the IPB mounting bracket secure, but the heatsink severely clogged with dust. Cleaned the heatsink, applied thermal paste, and reflashed the IPB thermal management strategy software. The fault has not returned.
BYD DTC AI Analysis

Qin PLUS DM-i discharged auxiliary battery caused RAM data error

✓
Qin Plus DM-i sat parked for one week with severely discharged battery (voltage <9V). After jump-starting, the instrument panel displayed multiple brake system warning lights. Diagnostics revealed active faults P060400 and P060A00 (Internal Control Module Monitoring Processor Performance). Analysis determined unstable IPB ECU reset voltage during low-voltage startup caused RAM initialization failure. Charged battery to full, cleared fault codes, and performed IPB power reset (disconnected battery negative terminal for 10 minutes). Fault codes did not recur; confirmed temporary RAM error caused by low voltage.
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.