AU
C050576

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

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.

The C050576 fault code on the Seal U indicates a plausibility fault in the left front wheel speed sensor signal. It is a medium severity issue that can affect ABS, ESC, and automatic emergency braking performance. Common causes include an unstable sensor signal from an internal electrical fault, or incorrect sensor-to-magnetic-ring clearance due to loose or damaged mounting parts. The recommended fix is to visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Open or short circuit in the front left wheel speed sensor internal coil (electromagnetic type) or Hall element signal drift, resulting in unstable output signal amplitude.
  • 2Deformed sensor mounting bracket, loose retaining bolts, or missing spacer causing the air gap between the sensor and the magnetic ring to exceed the standard range (0.3-1.2 mm).
  • 3Large amounts of iron filings or mud adhere to the surface of the wheel hub bearing magnetic encoder (magnetic ring), or the encoder exhibits physical damage or demagnetisation.
  • 4Sensor wiring harness insulation worn through at a suspension movement interference point, or oxidized or loose IPB control unit connector terminals B05/B06 interrupt signal transmission.
  • 5Inconsistent tyre sizes (such as fitting a space-saver spare wheel) or severely low left front tyre pressure causes the wheel speed difference to continuously exceed the system calibration threshold.
What To Do
  • 1
    Connect the VDS2000/VDS3100 diagnostic tool, read the C050576 freeze frame data, and 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 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. Inspect the connector waterproof sealing ring for aging.
  • 3
    Remove the left front wheel speed sensor and measure the sensor resistance using a multimeter. For the magnetic type, the standard value is 1.0-1.5kΩ (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. Inspect the magnetic ring for cracks, missing teeth, or demagnetization (measure magnetic field strength using a gauss meter). Check if the wheel hub bearing axial/radial play exceeds specifications.
  • 5
    Use a feeler gauge to measure the clearance between the sensor and the magnetic ring. If the clearance exceeds 1.2 mm, replace the mounting bracket or adjust the shims. Reinstall the sensor and tighten to the specified torque (usually 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 wiring harness continuity and insulation 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 Seal U Fault Codes
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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.