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C055700

DTC C055700 indicates the IPB (Intelligent Integrated Braking System) detects the left rear wheel speed sensor electrical characteristics, signal pulse count, or communication protocol do not match system calibration parameters during self-check or signal monitoring — Qin Plus

Braking System

DTC C055700 indicates the IPB (Intelligent Integrated Braking System) detects the left rear wheel speed sensor electrical characteristics, signal pulse count, or communication protocol do not match system calibration parameters during self-check or signal monitoring.

This fault is not a simple signal loss or short circuit; rather, the system identifies an abnormal sensor "identity".

Possible causes include installing a non-genuine wheel speed sensor with incorrect specifications (mismatched resistance, pole count, or Hall element type), an abnormal match between the sensor and the tone ring (magnetic ring), or incorrect IPB control module software configuration (such as flashing configuration data from another vehicle model).

This fault directly limits or completely disables functions relying on accurate wheel speed signals, including ABS, ESC, and EPB.

In extreme cases, it causes wheel lock-up or skidding during emergency braking, making it a critical fault affecting driving safety.

The C055700 fault code on the Qin Plus indicates the IPB braking system has detected an incorrect or mismatched left rear wheel speed sensor signal, not just a simple signal loss. Severity is medium because ABS, ESC, and EPB functions may be limited. Common causes include a non-genuine sensor or a mismatched wheel bearing magnetic ring. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Installed a non-genuine or incorrect wheel speed sensor (such as using a passive magnetic sensor from a conventional ICE vehicle instead of the BYD-specific Hall-effect sensor, or a sensor with a mismatched pole count).
  • 2The left rear wheel bearing unit (including the magnetic ring/tone ring) does not match the sensor. For example, installing an incorrectly specified bearing causes an abnormal number of magnetic poles or abnormal air-gap magnetic field strength.
  • 3IPB control module software programming error: programming an incorrect vehicle model configuration code (e.g., writing Tang model wheel speed parameters to a Song model) causes the system to misidentify the sensor model.
  • 4Water ingress, oxidized terminals, or abnormal contact resistance in the wheel speed sensor wiring harness connector alters the signal waveform characteristics, causing the system to misidentify the sensor type.
  • 5A deformed sensor mounting bracket or out-of-tolerance installation gap (standard: 0.3-1.2 mm) causes abnormal output signal amplitude, triggering a model identification fault.
What To Do
  • 1
    Use the BYD VDS2000/3000 diagnostic tool to read the complete fault codes and freeze frame data. Verify C055700 is a current fault and check for related fault codes such as C055600 (front right) and C055800 (rear right).
  • 2
    Check the EPC electronic parts catalog to verify the left rear wheel speed sensor part number (the Song PLUS DM-i typically uses a 3C-3630100 series Hall-effect sensor). Check the actual vehicle sensor part number, resistance (normally 1.0–1.5 kΩ), and pole count (typically 46 or 48 poles, depending on configuration).
  • 3
    Check sensor installation: Remove the left rear wheel speed sensor, check the tip for iron filings, measure the air gap between the sensor and the tone ring using a feeler gauge (must be 0.3-1.2 mm), and check the tone ring for missing teeth or deformation.
  • 4
    Use an oscilloscope to measure the sensor output signal: rotate the wheel and verify that the waveform is a standard square wave signal, the frequency is proportional to vehicle speed, and the amplitude is within the normal range (high level ≥4.5V, low level ≤0.5V).
  • 5
    Check the IPB control module software version and configuration code: Access IPB system special functions, read the vehicle model configuration information, and verify the configuration matches "Song PLUS DM-i". If incorrect, reflash the correct configuration or update to the latest software version.
  • 6
    Replace the wheel speed sensor with a genuine standard part (verify the part number matches the factory original). Clean the sensor mounting hole, tighten to the specified torque (usually 8-10Nm), and apply an appropriate amount of anti-seize grease.
  • 7
    Perform the sensor calibration procedure (if applicable): For some models, select the "Wheel Speed Sensor Learning" or "ABS System Bleeding and Calibration" function on the diagnostic tool. Clear the fault code, perform a road test, and confirm all four wheel speed data streams are synchronized and show no abnormal jumps.
Real-World Cases
BYD DTC AI Analysis

Aftermarket wheel speed sensor pole count mismatch caused C055700

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A 2021 BYD Song PLUS DM-i had its left rear wheel speed sensor replaced at a non-authorized repair shop following a left rear wheel accident. After driving approximately 500 km, the ABS and ESC warning lights illuminated on the instrument panel. Fault code C055700 was retrieved. Comparison showed the replacement sensor was a 48-pole unit, while the Song PLUS DM-i requires a 46-pole Hall sensor for the left rear wheel. Installing genuine part number 3C-3630100, performing IPB system calibration, and clearing the fault code restored normal wheel speed data for all four wheels.
BYD DTC AI Analysis

Software configuration error after IPB assembly replacement caused the fault.

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After the IPB pump body failed and was replaced with a new assembly, the technician failed to write the vehicle configuration before installation. This mismatch between the system default settings and the actual vehicle threw fault codes C055700 and C055600. Using a diagnostic tool, enter the IPB system "Vehicle Configuration" function, select the corresponding configuration code for "Song PLUS DM-i" (e.g., SA-XXX), and write the data. After the write succeeds, power down and let the system sleep for 5 minutes. The fault codes clear automatically. Dynamic testing confirms normal synchronization of all wheel speed signals.
BYD DTC AI Analysis

Rear wheel bearing replacement with incorrect magnetic ring specification

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LH rear wheel bearing noise. Replaced with an aftermarket bearing unit (with magnetic ring); DTC C055700 set. The replacement unit's built-in magnetic ring has 32 poles versus OEM 46, causing the IPB to flag the sensor output frequency as a model error. Replaced with OEM rear wheel bearing unit (with magnetic ring). Fault resolved. When replacing wheel hub bearings, confirm the magnetic ring pole count matches OEM.
BYD DTC AI Analysis

Water ingress into the sensor connector caused oxidation, resulting in abnormal signal characteristics.

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Water entered the left rear wheel speed sensor connector after driving through water, causing internal oxidation and increased signal line contact resistance. The distorted output signal waveform (slowed rising edge) caused the IPB to misdiagnose a sensor model error (C055700). Disassembling the connector revealed green corrosion on the pins. Cleaned the terminals, applied conductive grease, and confirmed normal resistance. Reinstalled the connector and cleared the fault code. Inspect chassis wiring harness waterproofing.
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.