AU
C050300

DTC C050300 indicates a short to battery positive (B+) in the left front wheel speed sensor (WSS) power supply circuit — Atto 3

Braking System

DTC C050300 indicates a short to battery positive (B+) in the left front wheel speed sensor (WSS) power supply circuit.

Normally, the IPB (Integrated Power Brake) supplies 5V or 12V to the wheel speed sensor (depending on sensor type).

A "short to battery" condition means the power supply line shorts to a vehicle constant power circuit, or the internal sensor power terminal breaks down to the signal or ground terminal.

This causes the control unit to detect an abnormally high voltage (approximately 12V battery voltage).

This prevents the IPB from correctly reading the left front wheel speed signal, triggers the safety protection mechanisms of systems such as ABS, ESP, and Automatic Emergency Braking, and disables the related functions.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Damaged left front wheel speed sensor wiring harness insulation contacting body power wires (e.g., headlight power supply, horn wires), causing a short circuit.
  • 2Sensor internal power supply circuit breakdown causes a short circuit between the power terminal and the housing or signal wire.
  • 3Water ingress, corrosion, or bent pins in the wheel speed sensor connector causing the power supply terminal to short to an adjacent power terminal.
  • 4After front-end accident repairs, improper wiring harness routing or detached retaining clips cause the wiring harness to rub against sharp edges, resulting in damage.
  • 5Internal power supply drive circuit fault in the IPB control unit causing abnormally high output voltage.
What To Do
  • 1
    Connect the VDS diagnostic tool, read and record the freeze frame data for DTC C050300, and confirm the vehicle speed and voltage status when the fault occurred.
  • 2
    Switch off the ignition, disconnect the left front wheel speed sensor connector, and check the connector terminals for corrosion, deformation, or signs of water ingress.
  • 3
    Turn the ignition switch to ON (do not start). Use a multimeter to measure the voltage between the sensor harness connector power supply terminal and ground: if the reading is 12V (battery voltage), this confirms a short to power. Normal voltage is 5V or 12V (depending on vehicle configuration), stable, and within sensor specifications.
  • 4
    Disconnect the IPB control unit connector. Measure the continuity of the left front wheel speed sensor power supply circuit between the sensor and the IPB. Measure the insulation resistance between this circuit and power (B+). The resistance must be greater than 10MΩ.
  • 5
    Check the sensor body resistance. The normal range is typically 1.0-1.5 kΩ (magnetic induction type) or meets Hall sensor specifications. If the resistance is abnormal, replace the sensor.
  • 6
    If the wiring harness has a short circuit, repair the damaged wiring (re-wrap or replace the harness section). If the sensor is faulty, replace it with a genuine wheel speed sensor. Clear the fault code and perform a road test to confirm normal ABS function.
Real-World Cases
BYD DTC AI Analysis

Left front wheel speed sensor harness worn through, short to power

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Vehicle: Song PLUS DMi 2022 model, 12,000 km. Symptoms: ABS and ESP warning lights constantly on; DTC C050300. Diagnosis: Lifted the vehicle and found the left front wheel speed sensor harness chafed through at the steering knuckle mounting point. The damage exposed internal copper wires that were touching the headlight power supply wire, causing a 12V short. Measured 12.5V at the sensor supply (abnormal). Fix: Soldered the damaged harness and insulated it with double-layer heat shrink tubing. Re-routed and secured the harness to prevent interference with steering components. Replaced the left front wheel speed sensor (possibly damaged by the short). Fault cleared.
BYD DTC AI Analysis

Water in the sensor connector caused a power supply short circuit.

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Vehicle: BYD Han EV. C050300 DTC set after driving through water. Found clear water staining and corrosion inside the left front wheel speed sensor connector. The power supply terminal had shorted to an adjacent constant-power terminal (possibly for the steering assist light). Cleaned and dried the connector, applied conductive grease, measured normal insulation, and cleared the fault. Recommend checking front wheel arch sealing.
BYD DTC AI Analysis

Aftermarket headlight modification damaged the wheel speed sensor wiring

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Vehicle: BYD Qin PLUS DMi. During a DIY LED headlight install, the owner secured the wiring with a clip that pierced the left front wheel speed sensor harness, shorting the sensor power feed to the headlight supply. The ABS warning light lit intermittently while driving. The scanner read C050300. Supply voltage changed with the headlight switch position. Repaired the harness and rerouted the wiring to resolve 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.