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C051176

The BYD IPB (Intelligent Integrated Braking System) defines DTC C051176 as "Incorrect Installation Direction of Left Rear Wheel Speed Sensor" — Qin Plus

Braking System

The BYD IPB (Intelligent Integrated Braking System) defines DTC C051176 as "Incorrect Installation Direction of Left Rear Wheel Speed Sensor".

This fault does not indicate a simple open or short circuit.

Instead, the magnetic pole direction of the Hall-effect wheel speed sensor mismatches the relative position of the tone ring, reversing the output square-wave signal phase or generating an abnormal duty cycle.

The IPB control unit triggers this code upon detecting unexpected rising and falling edge timing in the signal waveform, or upon identifying a logical conflict between the left rear wheel speed signal and the other three wheels during vehicle speed calculation.

This fault directly disables or falsely triggers the Anti-lock Braking System (ABS), Electronic Stability Program (ESP), Automatic Emergency Braking (AEB), and tire pressure monitoring system (calculated via wheel speed differentials), severely compromising driving safety.

4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Sensor body rotated 180° during installation: Technician failed to align the locating marks when inserting the sensor into the mounting hole after bearing or brake system replacement, reversing the Hall element magnetic pole direction relative to the tone ring.
  • 2Using a non-genuine aftermarket sensor: Some third-party parts have magnetic pole markings opposite to the genuine part or feature a mirrored internal Hall chip orientation. This results in correct physical installation but incorrect electrical direction.
  • 3Loose sensor mounting: Retaining bolts not tightened to the specified torque (8-10 N·m) or stripped steering knuckle mounting hole threads allow driving vibration to gradually rotate and shift the sensor out of position.
  • 4Abnormal sensor-to-tone ring air gap accompanied by steering deviation: When the air gap exceeds the standard 0.3-0.8 mm range, IPB signal phase tolerance decreases, and a slight steering deviation triggers the fault.
  • 5Wiring harness shield interference: An intermittent short circuit between the sensor signal wire (white) and the shield wire distorts the signal waveform, causing the control unit to falsely detect an incorrect installation direction.
What To Do
  • 1
    Connect the VDS2000/BYD dedicated diagnostic tool, read the IPB system fault codes to confirm C051176 is present, and record the freeze frame data (especially the vehicle speed and wheel speed values when the fault occurred).
  • 2
    Raise the vehicle to a suitable height, remove the left rear wheel, and visually inspect the wheel speed sensor appearance, connector locking tab, and wiring harness routing. Confirm the arrow mark on the sensor head points toward the wheel center/tone ring.
  • 3
    Disconnect the sensor connector and measure the supply voltage (12V±0.5V), ground wire continuity, and signal wire resistance (1.2-2.0kΩ at 20°C) to rule out basic circuit faults.
  • 4
    Remove the sensor. Clean the mounting hole and sensor tip. Inspect the tone ring for missing teeth, deformation, or oil contamination. Use a feeler gauge to measure the clearance between the sensor tip and the top of the tone ring teeth. Verify the clearance is 0.3-0.8 mm.
  • 5
    Reinstall the sensor according to the repair manual: align the sensor locating lug with the alignment slot in the steering knuckle mounting hole, orient the sensor arrow mark toward the inboard side of the wheel (magnetic pole facing the tone ring), and tighten the bolt to the specified torque of 8-10 N·m.
  • 6
    Connect the diagnostic tool and perform "Wheel Speed Sensor Position Learning" or "ABS Static Calibration" (some models require this step), then clear the fault code.
  • 7
    Perform a road test: Read the data stream at multiple speeds, including 10 km/h, 40 km/h, and 80 km/h. Confirm the left rear wheel speed signal synchronizes with the other three wheels and shows no jumps. Verify the ABS self-check and ESP functions operate normally.
Real-World Cases
BYD DTC AI Analysis

Installed ABS sensor backwards after wheel bearing replacement on Qin Pro, causing ABS warning light to come on

✓
At intake, the ABS and ESP warning lights stayed on constantly and the speedometer needle fluctuated at 40-60 km/h. The scan tool read codes C051176 and C003700. On the lift, the left rear wheel speed sensor showed signs of previous removal; the magnetic head direction mark was off by approximately 180 degrees. Further inspection found metal debris in the mounting hole. Cleaned the hole and reinstalled the sensor with the mark facing inward toward the wheel, setting the air gap to 0.5 mm. Cleared the faults and road-tested 10 km. Live data read normal and the warning lights went out.
Original source ↗
BYD DTC AI Analysis

Song Pro DM wiring harness chafing coupled with incorrect sensor orientation

✓
Dashboard displayed "Please check ESP system" and the reversing camera intermittently blacked out. DTCs C051176 and C050E00 set. Found the wiring harness crushed and damaged at the rear wheel arch liner, with the signal wire intermittently contacting the shield wire. Also found the sensor installed at the wrong angle; incorrect connector orientation misaligned the Hall element with the tone ring. Repaired the insulation and adjusted the routing. Reinstalled the sensor, ensuring the locating boss clipped into the mounting hole. Applied conductive paste and performed sensor calibration. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Loose sensor mounting bolts on a new Seal caused dual abnormalities in air gap and orientation.

✓
At 2000 km the new vehicle set tyre pressure and ESP faults; actual pressures were normal. Retrieved DTCs C051176 and C051000 (air gap abnormal). Inspection revealed loose mounting bolts. The sensor had shifted outward and rotated within its bore, causing magnetic pole misalignment. Air gap measured 1.2 mm, exceeding specification. Installed a new sensor (BYD-3630100), aligned it precisely with the anti-rotation feature, and torqued the bolts to 8 N·m. Performed ABS system calibration; fault cleared.
Original source ↗
BYD DTC AI Analysis

Aftermarket sensors fitted to the Han EV caused signal phase reversal.

✓
Frequent false ESP triggering on wet roads caused the dashboard to display a "Service ESP" warning. Data stream showed abnormal left rear wheel speed fluctuation below 10 km/h. Inspection revealed an aftermarket wheel speed sensor had been previously installed. Although the physical mounting direction appeared correct, oscilloscope testing showed the output waveform phase was reversed from OEM specification. Replaced the sensor with an OEM unit, cleaned oil from the tone ring, and performed static and dynamic calibration after proper installation. Waveform tests read normal and the fault has not returned.
Original source ↗
Other Qin Plus 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.