AU
C000A08

DTC C000A08 indicates the IPB (Integrated Power Brake) received a data packet from the ACC (Adaptive Cruise Control) controller containing a checksum error, missing data frame, or out-of-range signal — Qin Plus

Braking System

DTC C000A08 indicates the IPB (Integrated Power Brake) received a data packet from the ACC (Adaptive Cruise Control) controller containing a checksum error, missing data frame, or out-of-range signal.

The ACC controller (typically integrated into the MRR [Mid-Range Radar]) calculates the distance, relative speed, and angle of the target vehicle ahead.

It transmits this information in real time via the CAN bus to the IPB to execute Automatic Emergency Braking (AEB) and Adaptive Cruise Control.

The IPB logs "ACC data corruption" when it detects a CRC failure, abnormal data length, physically unreasonable values (e.g., sudden distance jumps), or a communication timeout.

This fault deactivates the AEB and ACC functions and triggers the "Automatic Emergency Braking Limited" message on the instrument cluster.

Basic hydraulic braking typically remains unaffected.

4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Internal software error or hardware fault in the MRR (mid-range radar) controller causing incorrect data frame transmission.
  • 2Interference, poor contact, or abnormal terminal resistance (standard: 60Ω) on the CAN communication line between the IPB and MRR.
  • 3MRR radar mounting position shifted due to collision or vibration, causing a mismatch between calibration data and the actual detection environment.
  • 4Faulty IPB internal receiver module or CAN transceiver, unable to correctly parse ACC data.
  • 5Vehicle 12V low-voltage power supply system fault (such as current leakage or voltage fluctuation) causing bit errors during data transmission.
What To Do
  • 1
    Use the VDS2000/VDS3100 diagnostic tool to read the complete fault codes, record freeze frame data, and check for accompanying U-class communication faults or MRR-related fault codes.
  • 2
    Visually inspect the MRR radar inside the front bumper. Verify the mounting bracket is not deformed or loose, and the radar surface is free of obstructions, damage, or heavy dirt.
  • 3
    Measure the voltage of the CAN-H and CAN-L lines between the MRR and IPB (static CAN-H approx. 2.6 V, CAN-L approx. 2.4 V) and the terminal resistance (measure with power off, standard value approx. 60 Ω).
  • 4
    Check the MRR and IPB power supplies (constant power and ignition ON power) and ground circuits. Verify the voltage is within 10-16V and the ground points are secure and free of oxidation.
  • 5
    Attempt to clear the fault code. Use the ADAS calibration tool to calibrate the horizontal and vertical angles of the MRR radar (requires a radar calibration board).
  • 6
    Update the IPB and MRR controller software to the latest version to eliminate data parsing errors caused by software bugs.
  • 7
    If the fault persists, first replace and recalibrate the MRR controller. If ineffective, replace the IPB integrated brake assembly.
Real-World Cases
BYD DTC AI Analysis

General Diagnostic Procedure for ACC Data Corruption (C000A08)

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Symptom: ACC failure, instrument cluster displayed brake system warning light, diagnostic tool read C000A08. Diagnosis: Checked CAN communication lines between MRR and IPB (measured CAN high + CAN low voltage sum), verified MRR supply voltage normal, inspected radar mounting position for accident-related misalignment. Resolution: Recalibrated MRR sensor (requires dedicated ADAS equipment), inspected and repaired wiring (cleaned ground point, replaced crooked connector), upgraded IPB system software or replaced MRR controller.
Original source ↗
BYD DTC AI Analysis

EPS System Fault Diagnosis Methods Reference (Wiring Harness Inspection)

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This case involves DTCs C1B1500 and C1B1600. Though addressing loss of EPS power steering assistance, the diagnostic procedure applies to C000A08: measure module supply voltage (check whether the ignition ON fuse is loose), verify connector voltage is within 10-16V, and inspect the wiring harness for open or short circuits. For C000A08, use the same approach to check the MRR controller power supply and communication lines for poor connections.
Original source ↗
BYD DTC AI Analysis

Reference case: Song DM leakage fault causing system communication failure

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DTCs: P1A0000 and others. Severe leakage (0.08 MΩ) with DC output at only 12.8 V caused low-voltage power supply faults. Vehicle presented with power steering failure, but voltage instability or leakage corrupts IPB-MRR controller communication packets, triggering C000A08 data corruption faults. Measure iron phosphate battery voltage stability, check the leakage sensor, and confirm the power system is normal before conducting ACC system diagnosis.
Original source ↗
BYD DTC AI Analysis

Steering System Sensor Calibration and Mechanical Inspection Reference

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DTCs: C1B0E00, C106600, and others. Symptoms include signal stuttering and angle inaccuracy. For C000A08, the MRR radar resembles the steering angle sensor—both require precise calibration. Key diagnostic steps: measure EPS module supply voltage, test sensor signals, check CAN network communication, and inspect external factors (e.g., vehicle level). The sensor recalibration procedure (requires specialist equipment) and the wiring harness ground point grinding method used here also work for ACC data corruption faults.
Original source ↗
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.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.