AU
P060400

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

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 Qin Plus indicates a RAM read/write checksum error inside the IPB brake control unit. This is a medium-severity internal memory fault that can reduce or disable ABS, ESP, AEB, or EPB functions. Common causes include IPB hardware memory damage or unstable power/ground supply. The recommended fix is to visit an authorised dealer for diagnosis and likely IPB ECU repair or replacement. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Hardware damage or aging of the IPB electro-hydraulic control unit internal RAM chip. 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 fluctuations, 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  • 3Defective or outdated IPB control software/firmware. A memory management flaw or overly sensitive RAM self-check algorithm causes false reports, or an actual memory leak triggers hardware protection.
  • 4Internal moisture or water ingress in the control unit, particularly due to poor sealing at the IPB installation location (engine compartment or cabin front bulkhead), causing PCB corrosion or pin-to-pin short circuits that affect RAM signal integrity.
  • 5Strong electromagnetic interference (EMI) or transient overvoltage in the vehicle electrical system (e.g., during startup, plugging or unplugging the DC fast charger, or starting or 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 and 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, cycle the ignition (OFF-ON-OFF), and observe if the fault code reappears immediately. If the fault is intermittent, check the IPB supply voltage (constant B+ should be 12.5-14.5V, IGN power stable) and ground resistance (<0.5Ω). Use an oscilloscope to monitor for voltage drops.
  • 3
    Check the IPB software version and compare it against the BYD TPI (Technical Product Information) bulletin to confirm if a software upgrade is available for P060400. If available, perform an IPB control unit software reflash or configuration reset.
  • 4
    Inspect the physical condition of the IPB. Disconnect and inspect the connector for water ingress, oxidation, and backed-out pins. Inspect the IPB housing for damage and signs of water seepage. 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 number varies 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

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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

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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

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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

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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

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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 Qin Plus 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.