AU
C050200

This DTC indicates the IPB (Intelligent Integrated Braking System) control unit detects an abnormally low-resistance connection between the left front wheel speed sensor (WSS) power supply circuit (typically a 12V DC supply) and body ground (GND), indicating a short to ground — Atto 8

Braking System

This DTC indicates the IPB (Intelligent Integrated Braking System) control unit detects an abnormally low-resistance connection between the left front wheel speed sensor (WSS) power supply circuit (typically a 12V DC supply) and body ground (GND), indicating a short to ground.

The wheel speed sensor uses a two-wire design (multiplexed power/signal or independent power and ground).

When the power supply circuit shorts to ground, the sensor fails to receive normal operating voltage.

This causes a complete loss of the left front wheel speed signal and prevents the IPB from monitoring the left front wheel speed.

This fault directly degrades or completely disables systems including the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Traction Control System (TCS), Automatic Emergency Braking (AEB), and Electronic Parking Brake (EPB).

The vehicle may enter a safety protection mode (limp mode) and brake pedal feel may change, severely compromising driving safety.

The C050200 fault code on the Atto 8 indicates a short to ground in the left front wheel speed sensor power supply circuit. This high-severity fault can stop the sensor signal and affect ABS, ESC, TCS, AEB, and EPB operation, reducing braking safety. Common causes include damaged wiring insulation rubbing on suspension or body parts, or an internal sensor circuit failure. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Atto 8
  • 1Damaged left front wheel speed sensor wiring harness insulation rubs against metal body components (such as the steering knuckle, lower control arm, or fender liner mounting screws) during suspension travel, causing the power wire to short to ground.
  • 2Internal breakdown of the wheel speed sensor drive circuit (such as a shorted Zener diode or filter capacitor), causing the power supply pin to short to the housing (ground).
  • 3Wheel speed sensor connector seal failure (seal ring aged or improperly installed) allows water or electrolyte ingress, causing a short circuit between the power supply pin and the ground pin.
  • 4The MOSFET or related protection component in the left front wheel speed sensor power supply drive circuit inside the IPB control unit failed, causing the output terminal to short to ground.
  • 5During vehicle modification (such as installing inner fender liners or sound-deadening material) or accident repairs, retaining screws crushing the wiring harness, clips pinching it, or hole edges cutting it damage the insulation.
What To Do
  • 1
    Visual inspection: Raise the vehicle, remove the left front wheel, and check the routing of the wheel speed sensor wiring harness near the fender liner, suspension spring seat, steering knuckle, and lower control arm. Inspect for wear, damaged insulation, crushing, or scorch marks. Check the connector for looseness, water ingress, corrosion, or recessed pins.
  • 2
    Voltage measurement: Disconnect the left front wheel speed sensor connector, turn the ignition switch to ON, and measure the voltage between the harness-side power supply pin and ground. Normal voltage is 12V (battery voltage). If the voltage is 0V or very low (<1V), a short circuit exists in the wiring harness or at the IPB. If the voltage is normal, the sensor may have an internal short to ground.
  • 3
    Resistance measurement: Turn off the ignition, disconnect the IPB control unit connector (or wheel speed sensor connector), and use a multimeter to measure the resistance between the left front wheel speed sensor power supply circuit and body ground. Normal resistance is greater than 10 MΩ (infinite). If the resistance is less than 1 Ω or continuity exists in buzzer mode, this confirms a short to ground.
  • 4
    Section-by-section troubleshooting: If testing confirms a harness short circuit, use the section-by-section measurement method (progressively peeling back the harness sleeve or disconnecting intermediate connectors from the sensor end to the IPB end) to pinpoint the short circuit. Closely inspect the harness where it passes through body openings, retaining clips, moving suspension components, and sections parallel to the front brake hose.
  • 5
    Component isolation verification: If the entire wiring harness tests normal (infinite resistance to ground), replace the left front wheel speed sensor and test. If the fault persists, reconnect the wiring harness and measure the resistance to ground at the corresponding output pin of the IPB control unit. If continuity exists, the IPB has an internal short circuit. Replace the IPB assembly.
  • 6
    Repair Verification: After repairing the wiring harness (re-wrapping with insulating tape, applying heat-shrink tubing, or replacing the wiring harness assembly) or replacing components, restore all connections. Use the diagnostic tool to clear the fault code. Perform a wheel speed sensor signal consistency check (read the data stream to confirm the left front wheel speed signal changes synchronously with the right front and rear wheel speeds while driving). Road test the vehicle to confirm the ABS/ESC warning light is off and the system functions normally.
Real-World Cases
BYD DTC AI Analysis

Song Plus DMi left front wheel speed sensor harness rubbing against suspension causing C050200

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While driving on rough roads, the ABS and ESC warning lights occasionally illuminated on the dash, clearing after an ignition cycle. The scanner retrieved DTC C050200, with freeze frame data showing the fault occurred at approximately 30km/h. Raised the vehicle and found the left front wheel speed sensor wiring harness had come loose from its retaining clip near the lower control arm, allowing the harness to rub against the suspension spring seat. Long-term chafing wore through the insulation, exposing the copper strands of the power wire and causing an intermittent short to ground. Repaired the damaged section by re-soldering the wires and insulating with heat shrink tubing. Re-routed and secured the harness, ensuring minimum 20mm clearance from all moving parts. Replaced the cable ties and protective sleeving. Fault eliminated.
BYD DTC AI Analysis

Internal circuit breakdown in the left front wheel speed sensor caused a short to power.

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After washing the vehicle, C050200 set immediately at startup and would not clear; the brake system warning light stayed on constantly. Disconnected the left front wheel speed sensor connector and measured 12V at the harness side, confirming normal IPB supply voltage. However, measuring between the sensor body pins and housing showed 0.3Ω between the supply pin and metal housing—an internal short to ground. Replaced the genuine left front wheel speed sensor (part number must match the IPB system version), cleared the fault codes, performed wheel speed sensor static calibration (Steering Angle Sensor and WSS Zero Calibration), and road-tested to confirm the repair. The sensor seal failed, allowing moisture into the internal circuit board and causing the power management chip to fail.
BYD DTC AI Analysis

Left front wheel speed sensor connector short circuit due to water ingress during rainy season

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After continuous heavy rain, the dashboard displayed a 'Brake System Fault' warning. Read DTC C050200. Inspection found water and green corrosion inside the left front wheel speed sensor connector, causing the power terminal to short to the ground housing and adjacent signal terminal. The connector seal had deteriorated and was missing, allowing water to splash in while driving through standing water. Cleaned the male and female terminals with electrical contact cleaner, sanded off the oxidation layer, replaced the waterproof seal, and applied insulating silicone grease at the connector mating surface to prevent further water ingress. Repaired the damaged corrugated tubing on the wiring harness to ensure waterproofing. Fault resolved.
BYD DTC AI Analysis

Internal drive circuit fault in IPB integrated brake unit

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PDI inspection on a new vehicle revealed DTC C050200; the code would not clear and the vehicle had not been driven. The left front wheel speed sensor harness showed no visible damage. At the sensor connector, the power supply line measured 0 Ω to earth (short circuit). They disconnected the 40-pin connector between the IPB control unit and harness and measured both sides: harness side pin 39 (left front WSS power supply) showed infinite resistance to earth (normal), while pin 39 on the IPB side showed continuity to earth. This indicated an internal short to earth in the IPB left front wheel speed sensor power supply drive circuit, likely from a production batch component defect. They replaced the IPB assembly (Intelligent Power Brake integrated braking unit), bled the system, calibrated the wheel speed sensor and longitudinal acceleration sensor, and cleared the fault.
Other Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.