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 6 EV

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 6 EV indicates an internal RAM read/write checksum error in the IPB brake control unit. This is a medium-severity fault that can put braking assist systems into degraded mode, affecting ABS, ESP, AEB, or EPB operation. Common causes include IPB internal memory hardware failure or unstable power/ground supply. Visit an authorised dealer for diagnosis and likely IPB repair or replacement. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Hardware damage or aging of the internal RAM chip in the IPB electro-hydraulic control unit. Physical semiconductor defects, electrostatic breakdown, or long-term thermal cycling stress typically cause this 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  • 3Defective or outdated IPB control software/firmware with memory management flaws or an overly sensitive RAM self-check algorithm, causing false DTCs or an actual memory leak that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 location (motor compartment or cabin front bulkhead), causes PCB corrosion or pin-to-pin short circuits, affecting RAM signal integrity.
  • 5Strong electromagnetic interference (EMI) or transient overvoltage in the vehicle electrical system (such as during startup, 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 is a current fault (Active), and record environmental parameters such as voltage and temperature from the Freeze Frame data.
  • 2
    Execute 'Clear DTCs', perform an ignition cycle (OFF-ON-OFF), and observe if the fault code reappears immediately. For intermittent faults, check the IPB supply voltage (constant B+ 12.5-14.5V, stable IGN power) and ground resistance (<0.5Ω). Use an oscilloscope to monitor for voltage drops.
  • 3
    Check the IPB software version and compare it against BYD TPI (Technical Product Information) bulletins to verify if a software update exists 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, 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 area and apply electrical contact protectant.
  • 5
    If the above steps fail, determine an IPB internal hardware fault. Replace the IPB electro-hydraulic brake assembly (part number depends on 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

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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

✓
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 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.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 Seal 6 EV →Seal 6 EV 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.