AU
C050B76

DTC C050B76 indicates the IPB (Intelligent Integrated Braking System) detects a correlation fault in the right front wheel speed sensor signal — Atto 3

Braking System

DTC C050B76 indicates the IPB (Intelligent Integrated Braking System) detects a correlation fault in the right front wheel speed sensor signal.

This fault does not indicate a simple signal loss (open circuit).

Instead, the sensor pulse signal output logically mismatches actual vehicle dynamics (e.g., other wheel speeds, vehicle speed, acceleration, yaw rate), or the signal characteristics (frequency, amplitude, duty cycle) exceed calibrated thresholds.

The IPB algorithm compares the correlation of all four wheel speed sensors.

The system sets this code when the right front signal differs excessively from the other wheel speeds, exhibits erratic signal jumps, or experiences an intermittent fault in the sensor power supply or ground circuit.

This fault directly affects the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Automatic Emergency Braking (AEB), and energy recovery functions.

It may increase braking distance or cause abnormal brake pedal feel.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1A degraded right front wheel speed sensor or internal coil inter-turn short circuit causes insufficient output signal amplitude or waveform distortion, reducing signal quality especially at high temperatures or high speeds.
  • 2Abnormal air gap between the sensor and magnetic encoder ring (tone ring) (greater than 1.2 mm or less than 0.3 mm). Common causes include a loose sensor retaining bolt, a deformed bracket, or bearing wear causing axial play in the wheel hub.
  • 3Damage to the right front wheel hub unit magnetic encoder ring (demagnetization, cracks, or attached iron debris) causes uneven magnetic flux variation, resulting in signal noise or missing tooth signals.
  • 4Intermittent sensor wiring harness fault, including poor contact at IPB control unit connector pin 26 (signal), pin 25 (power supply), or the body ground circuit, and wiring harness wear causing a short circuit during suspension movement.
  • 5Inconsistent tyre sizes or severely unbalanced tyre pressures cause a systematic deviation between the actual rotational speed of the right front tyre and the other tyres, triggering an IPB correlation check failure.
What To Do
  • 1
    Use a diagnostic tool to read the freeze frame data. Confirm the vehicle speed, wheel speed values, and IPB supply voltage when the fault occurred. Check for accompanying fault codes (e.g., C050A00, U0121). Clear the fault codes and perform a road test. Monitor the right front wheel speed data stream for jumps or loss of synchronization with the other wheel speeds.
  • 2
    Raise the vehicle and visually inspect the right front sensor. Verify the mounting bolt torque (standard: 8-12 N·m). Check the wiring harness for tension at full steering lock. Measure the sensor resistance (standard: 1.5-2.5 kΩ at 20°C). Measure the sensor supply voltage (ignition ON: 12V ± 0.5V).
  • 3
    Remove and inspect the right front wheel speed sensor. Use a feeler gauge to measure the radial gap between the sensor tip and the magnetic encoder ring (standard: 0.3-1.2 mm). Inspect the encoder ring surface for scratches, corrosion, or foreign matter. After cleaning, check magnetic pole integrity (test magnetic distribution using iron filings).
  • 4
    Use an oscilloscope to monitor the sensor signal waveform. Slowly rotate the wheel and verify a regular square or sine wave. Check for spikes, flat tops, or missing pulses. Compare the waveform with the left front wheel to confirm consistent amplitude and frequency.
  • 5
    If the above checks are normal, perform the IPB system calibration procedure (via the diagnostic tool: IPB Special Functions → Wheel Speed Sensor Calibration) and verify the IPB software is the latest version (compare against the TPI technical bulletin). If the fault is intermittent, inspect pin 26 of IPB harness connector X1 (right front wheel speed signal) for looseness or oxidation.
Real-World Cases
BYD DTC AI Analysis

Worn right front bearing on Song PLUS DM-i causing excessive clearance

✓
A 2021 Song PLUS DM-i with 60,000 km intermittently illuminated the ABS and ESC warning lights on the instrument panel. The scan tool retrieved DTC C050B76. Freeze frame data showed the fault occurred at 60 km/h when the right front wheel speed signal suddenly dropped to zero. Inspection found 0.8 mm of axial play in the right front hub bearing, causing the air gap between the magnetic encoder ring and sensor to vary dynamically while driving. Replaced the right front hub assembly (including the encoder ring) and adjusted the sensor air gap to 0.6 mm. Fault resolved.
BYD DTC AI Analysis

Sensor harness chafed at steering knuckle and shorted

✓
DTC C050B76 appeared after the vehicle drove through water, accompanied by restricted Automatic Emergency Braking function. Inspection found the right front wheel speed sensor wiring harness chafed where it passes through the steering knuckle bracket, with the copper core intermittently shorting to the body. The fault showed normal operation at low speeds but signal abnormalities during high-speed cornering when the harness stretched. Repaired the damaged wiring, reinforced the insulation with heat shrink tubing, and re-secured the harness routing to prevent contact with suspension components.
BYD DTC AI Analysis

Mismatched tyre specifications caused related faults

✓
The owner replaced the right front tyre; the warning light illuminated the next day showing DTC C050B76. Inspection revealed the new tyre was size 225/55R18, while the original and other three tyres were 225/60R18, causing the right front rolling circumference to differ from the other wheels by approximately 3%. The IPB system flagged the right front sensor signal as faulty based on four-wheel speed differential logic. Fitting the correct size tyre and performing tyre pressure calibration cleared the fault.
BYD DTC AI Analysis

Oxidized IPB control unit connector caused signal drift

✓
Southern humid region vehicle. After one week parked, C050B76 triggered immediately at startup. Sensor power supply normal, but signal line voltage fluctuated between 0.5–3V (normal: 0–12V pulse). Disconnected IPB control unit connector; pin 26 (right front wheel speed signal) showed green corrosion. Cleaned connector with electronic contact cleaner, applied conductive grease, and replaced terminals as needed. Fault resolved.
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.