AU
P060400

DTC P060400 indicates a read/write checksum error in the RAM (Random Access Memory) of the IPB (Integrated Power Brake) control unit — Atto 8

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.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 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 memory cell failure.
  • 2Abnormal IPB ECU power supply system, including battery voltage fluctuation, unstable ignition power (IGN), or poor ground connection, causing RAM bit flips or data loss 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  • 3Defective or outdated IPB control software/firmware with memory management vulnerabilities or an overly sensitive RAM self-check algorithm, causing false faults or an actual memory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 (engine compartment or cabin front bulkhead), causes PCB corrosion or short circuits between pins, compromising RAM signal integrity.
  • 5Strong electromagnetic interference (EMI) or transient overvoltage in the vehicle electrical system (e.g., during startup, fast charger connection/disconnection, or high-power component switching) 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 to confirm if P060400 is present and is a current fault (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 observe if the fault code immediately reappears. If the fault is intermittent, check the IPB supply voltage (constant B+ should be 12.5-14.5V, IGN power supply stable) and ground resistance (<0.5Ω). Monitor for voltage drops using an oscilloscope.
  • 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 parameter reset.
  • 4
    Inspect the physical condition of the IPB. Disconnect and inspect the connector for water ingress, oxidation, or backed-out pins. Inspect the IPB housing for damage or signs of water seepage. Measure the internal insulation resistance using an insulation tester. If moisture is present, dry the component and apply electrical contact protectant.
  • 5
    If the above steps fail, the fault is an internal IPB hardware failure. Replace the IPB electro-hydraulic brake assembly (part number depends on vehicle model, e.g., Song PLUS DM-i: 351XXX-XXXX). 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 Atto 8 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.