AU
C050C00

DTC C050C00 indicates the IPB (Integrated Intelligent Brake Control System) detects an electrical fault in the left rear wheel speed sensor (WSS) wiring harness, including an open circuit, short circuit, or short to ground or power — Atto 8

Braking System

DTC C050C00 indicates the IPB (Integrated Intelligent Brake Control System) detects an electrical fault in the left rear wheel speed sensor (WSS) wiring harness, including an open circuit, short circuit, or short to ground or power.

This sensor, typically a Hall-effect or magnetoelectric type, converts wheel speed into an electrical signal and transmits it to the IPB module.

The IPB module uses this signal for precise control of systems including ABS, ESC, TCS, EPB, and Automatic Emergency Braking (AEB).

A wiring harness fault prevents the IPB from obtaining left rear wheel speed data and triggers a system degraded mode (ABS/ESC functions limited or disabled).

In extreme cases, this fault can affect brake force distribution, cause abnormal parking brake operation, or trigger speed-limiting protection, posing a driving safety risk.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Loose connection, backed-out terminals, water ingress, or corrosion in the left rear wheel speed sensor wiring harness connector, causing increased contact resistance.
  • 2Wiring harness worn, chafed, or completely broken at moving suspension parts (such as near the steering knuckle, control arm, or shock absorber) due to detached retaining clips.
  • 3Sensor internal coil burnt out, Hall element failed, or probe damaged.
  • 4The wheel bearing magnetic encoder ring (magnetic ring) is damaged, detached, or contaminated with excessive iron debris, generating an abnormal signal that the system misdiagnoses as a wiring harness fault.
  • 5Internal circuit fault at the IPB control module left rear wheel speed signal input interface (e.g., burnt sampling resistor or shorted filter capacitor).
What To Do
  • 1
    Use the VDS2000/VDS3000 diagnostic tool to read the fault code and freeze frame data. Confirm the vehicle speed, road conditions, and related fault codes at the time of the fault. Check if the left rear wheel speed data stream reads 0 or shows abnormal jumps.
  • 2
    Raise the vehicle to a suitable height and visually inspect the entire left rear wheel speed sensor wiring harness. Check the protective sleeve for damage, chafing, or water ingress, particularly where it passes through body holes and near the suspension control arm and shock absorber.
  • 3
    Disconnect the left rear wheel speed sensor connector and the IPB module connector. Use a multimeter to measure harness continuity (resistance between pins <1Ω), and check for short to ground (resistance to vehicle body >10MΩ) and short to power (resistance to +B >10MΩ).
  • 4
    Check the connector terminals for green oxidation, terminal spread, deformation, or backed-out pins. Clean with electrical contact cleaner. Replace the connector or repair the terminals if necessary.
  • 5
    Connect the sensor connector, turn the ignition ON, and measure the sensor supply voltage (should be 5V ± 0.25V) and the signal wire reference voltage (approximately 2.5V). Turn the wheel by hand and observe the signal voltage for pulse changes (alternating between 0.5V and 4.5V).
  • 6
    If the wiring harness and power supply are normal, replace the left rear wheel speed sensor. Observe the installation gap (usually 0.3-1.2 mm, depending on vehicle model) and tightening torque (usually 8-12 N·m) to prevent an excessive gap from causing signal loss.
  • 7
    Clear the fault code, perform sensor calibration (if required), and perform a road test to verify: drive at 20-40 km/h or above, observe the diagnostic tool data stream to verify the left rear wheel speed matches the other wheel speeds, and confirm the instrument cluster warning light turns off and system functions return to normal.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i – Left rear wheel speed sensor wiring harness oxidised, causing intermittent fault

✓
The instrument cluster intermittently illuminated ABS and ESC warning lights with DTC C050C00 logged. Inspection of the left rear wheel speed sensor harness revealed water ingress and oxidation in the body-to-chassis harness connector (located near the left rear sill), causing increased signal resistance and abnormal voltage drop. The technician cleaned the connector terminals, sprayed electronics cleaner, applied conductive grease, and reconnected the harness with waterproofing. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Qin Pro EV left rear wheel speed sensor harness worn through, open circuit

✓
Driving on rough roads, the dashboard suddenly displayed "Please Check Brake System" with DTC C050C00. Lifted the vehicle and found the wiring harness retaining clip at the left rear suspension had detached. The harness had been rubbing against the lower control arm, wearing through the insulation and breaking the internal copper wires. Repaired and re-wrapped the harness, secured it along standard routing with >50mm clearance from moving parts. Cleared the DTC; road test normal.
Original source ↗
BYD DTC AI Analysis

Han EV left rear wheel speed sensor damage misdiagnosed as wiring harness fault

✓
C050C00 set immediately on startup after overnight parking and would not clear. Initial checks confirmed normal wiring harness continuity and 5V supply, but sensor resistance measured infinite (normal: 1.2–1.8kΩ). Replaced the left rear wheel speed sensor, cleared the fault code with a diagnostic tool, and performed wheel speed sensor signal calibration (requires driving more than one complete revolution for the IPB to learn the tone ring error). Fault resolved. The original sensor had an internal coil open circuit, causing the IPB to misdiagnose this as a wiring open circuit fault.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS DM-i IPB module internal interface fault

✓
Replaced the left rear wheel speed sensor and complete wiring harness, but DTC C050C00 persisted. Data stream showed left rear wheel speed constantly at zero. Pin measurements at the IPB module revealed an internal open circuit between the left rear wheel speed signal input pin and the sampling circuit (internal module fault). Replaced the IPB integrated brake control module assembly and strictly performed brake system bleeding, ESC calibration, and longitudinal acceleration sensor calibration. Fault completely resolved.
BYD DTC AI Analysis

Tang DM wheel hub bearing magnetic encoder ring damage causing associated faults

✓
DTC C050C00 accompanied by left rear wheel noise while driving. Disassembly revealed the wheel hub bearing magnetic encoder ring (magnetic ring) had rusted and flaked from prolonged water exposure, preventing the sensor from reading the correct speed signal. After multiple failed communication attempts, the IPB misdiagnosed this as a wiring harness open circuit. Replaced the left rear wheel hub bearing unit, thoroughly cleaned residual iron filings from the sensor probe, and set the correct clearance between the sensor and tone ring during installation. Fault resolved.
Other Atto 8 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.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.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.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
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.