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C051D01

DTC C051D01 indicates an abnormal calibration status of the inertial measurement unit (IMU) inside the IPB (Integrated Power Brake) — Qin Plus

Braking System

DTC C051D01 indicates an abnormal calibration status of the inertial measurement unit (IMU) inside the IPB (Integrated Power Brake).

Specifically, the yaw rate sensor or longitudinal acceleration sensor reference data is lost, offset, or invalid.

Integrated inside the IPB control module, this sensor monitors the vehicle’s rotational yaw rate about the vertical axis and its longitudinal acceleration in real time.

It provides the core input signal the ESP electronic stability control system uses to calculate vehicle dynamic attitude.

The IPB sets this code when it detects the sensor output deviates from the expected calibration reference beyond the threshold, or when it loses the stored calibration parameters.

This limits ESP functionality or triggers limp mode; however, normal hydraulic braking usually remains unaffected.

The C051D01 fault code on the Qin Plus indicates an abnormal calibration status in the IMU sensor inside the Integrated Power Brake module. Severity is medium: ESP stability control may be limited, but normal hydraulic braking usually remains available. Common causes include lost calibration after IPB replacement or battery depletion, or a loose/shifted IPB module mount. Visit an authorised dealer for IMU calibration and mounting checks. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Failure to perform the IMU sensor calibration procedure after replacing the IPB assembly, disconnecting the battery, or prolonged battery depletion, resulting in calibration data loss.
  • 2Loose IPB control module mounting bracket, insufficient fixing bolt torque, or external impact to the module caused the internal inertial sensor's physical reference to shift.
  • 3After a vehicle software update (OTA or diagnostic tool), the IPB control program updated, but the calibration data failed to synchronously reset or match.
  • 4Aging of the Inertial Measurement Unit (IMU) hardware inside the IPB, chip overheating, or cold PCB solder joints causes signal drift beyond the self-test tolerance.
  • 5Extreme electromagnetic interference or power supply voltage fluctuations (such as jump-starting or abnormal generator voltage regulation) corrupt memory calibration parameters.
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS or ED400) to read the complete IPB system fault codes and freeze frame data. Check for related fault codes accompanying C051D01, such as C006A02 (signal error) or C00A800 (not calibrated).
  • 2
    Visually inspect the IPB control module for external damage. Verify the module mounting bracket is free of deformation. Tighten the mounting bolts to the specified torque (usually 8-10N·m). Ensure the module mounting surface is parallel to the vehicle body reference surface.
  • 3
    Measure the IPB supply voltage (B+ to ground) and verify the battery voltage is ≥12V with no loose connections. Check the CAN-H and CAN-L communication line voltages (2.5V ± 0.1V) and terminating resistance (approximately 60Ω).
  • 4
    Perform the sensor calibration procedure: park the vehicle on a level surface, center the steering wheel (within ±5°), close all doors, access the 'Sensor Calibration' or 'IMU Calibration' function in the diagnostic tool's IPB system, and sequentially complete the yaw rate sensor zero-point calibration and longitudinal acceleration sensor calibration (some models require simultaneous pressure sensor calibration).
  • 5
    After successful calibration, clear the fault code and perform a dynamic road test including straight-line acceleration, steady-speed cruising, left and right steering (to generate yaw moment), and emergency braking. Verify the instrument cluster ESP/ABS warning light is off and the system does not intervene abnormally.
  • 6
    If the calibration procedure aborts, fails, or the fault code returns, diagnose an internal IPB hardware fault and replace the IPB assembly. After replacement, perform new module coding and configuration, VIN writing, and complete sensor calibration.
Real-World Cases
BYD DTC AI Analysis

ESP warning light on after suspension repair (yaw rate sensor not calibrated)

✓
After the 4S shop replaced the front shock absorbers and lower control arms on a Song Plus DM-i, the instrument cluster showed a steady ESP warning light and the steering wheel felt abnormal self-centering torque when turning. VDS read IPB system fault code C051D01; freeze frame data showed the fault occurred at 0 km/h. Inspection found technicians disconnected IPB-related wiring harnesses during the chassis repairs and skipped sensor calibration afterward. We performed the "Yaw Rate Sensor Zero Position Calibration" procedure on level ground, cleared the fault codes after calibration, and road-tested 5 km to confirm ESP function returned to normal and the warning light went out.
Original source ↗
BYD DTC AI Analysis

IPB system warning after software upgrade (calibration data lost)

✓
After an OTA software update, the Qin PLUS DM-i started up the next day with the ESP and ABS warning lights and a 'Check Brake System' alert on the instrument cluster, and entered limp mode. The diagnostic scanner showed IPB system DTCs C051D01 (Yaw Rate Sensor Calibration Error) and C006A02 (Yaw Rate Sensor Signal Error). Technicians determined the IPB control logic had updated during the software upgrade, but the internal IMU calibration data had not synchronized. Using an ED400 diagnostic tool, they accessed the IPB system and ran the 'Integrated Sensor Calibration' procedure (longitudinal acceleration, yaw rate, and master cylinder pressure sensor calibration). The system passed self-checks after calibration. They cleared the fault codes and road-tested; brake force distribution and stability control functioned normally.
Original source ↗
BYD DTC AI Analysis

IPB internal IMU hardware failure caused calibration failure.

✓
A Song PLUS DM-i with 30,000 km and no collision or repair history sat stationary overnight. The next morning at startup, the dashboard suddenly showed an ESP warning. Only DTC retrieved: C051D01. Freeze frame showed the vehicle completely stationary when the fault occurred, battery voltage normal at 12.4V. Attempted sensor calibration; the scan tool returned 'Calibration failed - sensor signal out of tolerance'. Checked IPB power supply and ground—both normal. Diagnosed as internal Inertial Measurement Unit (IMU) chip hardware fault or dry solder joint in the IPB, causing permanent signal baseline offset. Replaced the IPB assembly (part number 6A-3630100). After replacement, performed coding, VIN configuration, and sensor calibration on the new module. Fault completely resolved.
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.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.