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C051D01

DTC C051D01 indicates an abnormal calibration status of the inertial measurement unit (IMU) inside the IPB (Integrated Power Brake) — Seal 6 EV

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 Seal 6 EV indicates a medium-severity calibration problem with the IMU sensor inside the Integrated Power Brake module. The yaw rate or longitudinal acceleration reference data may be lost, offset, or invalid, which can reduce ESP stability control function while normal braking usually remains. Common causes include missed calibration after IPB or battery work, or a loose/shifted module mounting. Visit an authorised dealer for calibration and inspection. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Failure to perform the IMU sensor calibration procedure after replacing the IPB assembly, disconnecting the battery, or experiencing prolonged vehicle power loss results in calibration data loss.
  • 2A loose IPB control module mounting bracket, insufficient mounting bolt torque, or external impact to the module caused the physical reference of the internal inertia sensor to shift.
  • 3After a vehicle software upgrade (OTA or diagnostic tool), the IPB control program updates, but the calibration data fails to reset or match synchronously.
  • 4Hardware aging of the Inertial Measurement Unit (IMU) inside the IPB, chip overheating, or poor PCB solder joints causes signal drift exceeding 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. Confirm if C051D01 occurs with related fault codes 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 not deformed. Tighten the fixing bolts to the specified torque (usually 8-10 N·m). Ensure the module mounting surface is parallel to the vehicle body reference plane.
  • 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 (approx. 60Ω).
  • 4
    Perform the sensor calibration procedure: Park the vehicle on level ground, center the steering wheel (within ±5°), and close all doors. Access the IPB system on the diagnostic tool, select the 'Sensor Calibration' or 'IMU Calibration' function, 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, constant-speed cruising, left and right turns (to generate yaw moment), and emergency braking. Verify the ESP/ABS warning lights on the instrument cluster turn off and the system does not intervene abnormally.
  • 6
    If the calibration procedure aborts, fails, or the fault code returns, this indicates an internal IPB hardware fault. Replace the IPB assembly. After replacement, perform new module coding, VIN writing, and a 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 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.