AU
C050576

This DTC indicates the IPB (Integrated Intelligent Braking System) detects a correlation plausibility fault in the left front wheel speed sensor signal — Atto 3

Braking System

This DTC indicates the IPB (Integrated Intelligent Braking System) detects a correlation plausibility fault in the left front wheel speed sensor signal.

Specifically, the frequency or amplitude of the sensor pulse signal logically conflicts with the actual vehicle motion state, the other three wheel speed signals, or the longitudinal acceleration sensor data, failing the system plausibility check algorithm.

This fault typically indicates intermittent sensor signal interruption, electromagnetic interference, magnetic ring (magnetic encoder) demagnetization, or out-of-tolerance mechanical installation clearance.

These conditions prevent the ABS/ESC from accurately identifying the actual left front wheel speed, triggering the ABS warning light and ESC OFF light, and degrading the automatic emergency braking system.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Open or short circuit in the front left wheel speed sensor internal coil (magnetic induction type) or Hall element signal drift, causing unstable output signal amplitude.
  • 2Deformed sensor mounting bracket, loose retaining bolts, or missing shim causes the air gap between the sensor and magnetic ring to exceed the standard range (0.3-1.2mm).
  • 3Wheel hub bearing magnetic encoder (magnetic ring) surface has a heavy accumulation of iron filings or mud, or exhibits physical damage or demagnetization.
  • 4Sensor wiring harness insulation wears through at a suspension movement interference point, or oxidized or loose terminals B05/B06 on the IPB control unit connector interrupt signal transmission.
  • 5Inconsistent tyre sizes (e.g., fitting a non-full-size spare) or severely low left front tyre pressure, causing the wheel speed difference to continuously exceed the system calibration threshold.
What To Do
  • 1
    Connect the VDS2000/VDS3100 diagnostic tool and read the C050576 freeze frame data. Record the vehicle speed, left front wheel speed, steering wheel angle, and longitudinal acceleration at the time of the fault. Check for other accompanying sub-codes in the C050500-C050599 series.
  • 2
    Raise the vehicle until the wheels are off the ground. Visually inspect the left front wheel speed sensor wiring harness at the steering knuckle and lower control arm retaining clips for wear or stretching. Check the connector waterproof sealing ring for aging.
  • 3
    Remove the left front wheel speed sensor. Use a multimeter to measure the sensor resistance: the standard value for the magnetic type is 1.0-1.5 kΩ (20°C); for the Hall type, check the supply voltage (12V/5V) and signal output. Inspect the sensor tip for metal debris.
  • 4
    Clean the magnetic encoder surface. Check the magnetic ring for cracks, missing teeth, or demagnetization (measure the magnetic field strength using a gauss meter). Check if the wheel hub bearing axial/radial play exceeds specifications.
  • 5
    Measure the installation gap between the sensor and magnetic ring using a feeler gauge. If the gap exceeds 1.2 mm, replace the mounting bracket or adjust the shims. Reinstall the sensor and tighten to the specified torque (typically 8-12 N·m).
  • 6
    Perform a dynamic test: Shift to D and slowly rotate the wheels. Read the data stream to verify the left front wheel speed signal synchronizes with the other wheel speeds without dropouts. Perform a road test to verify ABS/ESC function recovery, then clear the fault code.
  • 7
    If the above checks are normal, measure the continuity and insulation of the wiring harness between the IPB control unit terminals and the sensor. If necessary, update the IPB software to the latest version or replace the IPB assembly.
Real-World Cases
BYD DTC AI Analysis

Worn sensor wiring harness causing intermittent fault — Song PLUS DM-i

✓
ABS warning light illuminated intermittently when driving on rough roads. Scan tool read C050576 as an intermittent fault. Inspection revealed the left front wheel speed sensor wiring harness had chafed through the insulation at the lower control arm mounting point, causing the copper conductors to intermittently short to ground. Repaired the damaged harness, rerouted the wiring with corrugated tube protection, and secured it with cable ties clear of moving parts. Fault resolved.
BYD DTC AI Analysis

Metal debris on reluctor ring surface caused erratic signal

✓
The owner reported premature ABS activation during braking. Inspection found the left front wheel hub magnetic encoder had accumulated significant brake dust and metallic road debris, causing wheel speed sensor signal amplitude fluctuations. Cleaned the magnetic ring and test drove, but fault codes still appeared intermittently. Further inspection revealed the sensor tip was worn. Replaced the left front wheel speed sensor and thoroughly cleaned the magnetic ring. Fault resolved.
BYD DTC AI Analysis

Excessive wheel bearing play caused the reluctor ring to scrape

✓
The ESC warning light suddenly illuminated at highway speed. Live data revealed the left front wheel speed signal intermittently dropping to zero. Disassembly revealed the left front wheel hub bearing radial clearance exceeded specifications (>0.1 mm), causing dynamic interference between the magnetic ring and sensor. The sensor tip was scratched. Replaced the left front wheel hub bearing assembly (including magnetic ring) and wheel speed sensor. Fault eliminated.
BYD DTC AI Analysis

Non-full-size spare tyre caused wheel speed variance to exceed limits

✓
Replaced the left front tyre with a space-saver spare and drove. Multiple system warnings lit up on the dash. Scanner logged C050576 rationality fault. Found the spare diameter ~6% smaller than the standard tyre, causing the left front wheel speed to read consistently higher than the others. Fitted a standard-spec tyre, adjusted pressure to 2.5 bar, cleared the fault codes. System returned to normal.
BYD DTC AI Analysis

IPB software calibration error caused false alarm.

✓
During new vehicle PDI, found active fault C050576. Sensor and wiring harness checked normal; signal waveform standard. Technical service bulletin revealed IPB software V1.2 on this batch has an overly sensitive wheel speed rationality algorithm. Upgraded IPB control unit software to V1.5, performed sensor calibration, and eliminated the fault.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.