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C051776

The IPB (Intelligent Integrated Braking System) or ESC (Electronic Stability Control System) triggers this DTC — Seal U

Braking System

The IPB (Intelligent Integrated Braking System) or ESC (Electronic Stability Control System) triggers this DTC.

It indicates a wrong installation direction for the right rear wheel speed sensor.

The sensor uses the Hall effect principle; its internal magnetic poles have a specific bias direction to identify the tone ring rotational direction.

Installing the sensor opposite to the calibrated direction, or swapping the left and right sensors, produces an output signal polarity opposite to ECU expectations.

This prevents the system from correctly interpreting the wheel speed signal.

This condition degrades or disables functions such as ABS, ESP, Auto Hold, and Automatic Emergency Braking, representing a brake safety-related functional fault.

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Cases Logged
Real-World Cases
BYD DTC AI Analysis

BYD Yuan Plus sets C051776 after wheel speed sensor replacement

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The owner reported that while driving normally, the ABS and ESP warning lights suddenly illuminated on the dashboard with a 'Check ESP System' message. The vehicle jerked when pulling away, and the auto hold function failed. The technician used a diagnostic scanner and retrieved fault code C051776 (Right Rear Wheel Speed Sensor Incorrect Installation Direction). The technician first checked the right rear wheel speed sensor connector and found no looseness or water ingress. The owner stated that a non-dealership workshop had replaced the right rear wheel speed sensor one week prior. The technician removed the right rear wheel for inspection and found that although the replacement wheel speed sensor matched the original part number, the arrow marking on the sensor housing pointed opposite to the left rear wheel. According to the workshop manual, this sensor is directional and requires correct installation orientation to identify the tone ring rotation direction. Solution: Reinstalled the right rear wheel speed sensor with the direction arrow on the sensor housing pointing toward the front of the vehicle (mirror image of the left rear sensor). After clearing the fault codes and road testing, the ABS and ESP warning lights turned off, live data showed normal right rear wheel speed signals, and the auto hold function returned to normal.
Original source ↗
BYD DTC AI Analysis

New Seal 06 DM-i inspection found C051776

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A new vehicle with only 2000 km. At the first service, the owner reported the ESP warning light occasionally flickered but extinguished automatically. The dealership technician connected a VDS scan tool and found stored fault codes C051776 (Right rear wheel speed sensor installation direction error) and C051600 (Right rear wheel speed sensor abnormal air gap). The technician raised the vehicle and inspected the right rear wheel. The wheel speed sensor retaining bolt torque was normal, but the sensor and bearing unit were not original matching parts. Further inspection revealed the sensor was a used part removed from a different batch of vehicles. Although the part number matched, different manufacturing batches resulted in opposite internal magnetic polarity. Because the Seal 06 uses an integrated bearing unit, the wheel speed sensor and bearing are matched components; an incorrect batch or sensor direction causes signal phase errors. Solution: Replaced the right rear wheel bearing unit (including wheel speed sensor) with a brand new part matched to the VIN. During installation, ensure the sensor connector faces the correct direction and tighten the bolt to standard torque (typically 8–12 N·m) using a torque wrench. Perform sensor calibration and road testing. The fault codes did not reappear.
Original source ↗
BYD DTC AI Analysis

BYD Song Plus DM-i sets C051776 after accident repair

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Vehicle sustained a collision on the right rear side. A general repair shop carried out repairs to the rear axle and right rear wheel area. After delivery, the owner noticed abnormal ESP intervention during straight-line driving and unstable speedometer readings at high speeds. Fault code C051776 stored and would not clear. The technician compared right and left rear wheel speed sensor live data, finding significant discrepancies at low speeds, with abnormal spikes in the waveform. Disassembly revealed that although the repair shop had installed a genuine right rear wheel bearing, they failed to observe the wheel speed sensor orientation. Further inspection showed this model uses Hall effect wheel speed sensors that are direction-sensitive; reverse installation reverses signal polarity. Solution: Remove the right rear brake disc and bearing unit and reposition the wheel speed sensor in the correct orientation. Due to the high integration of the bearing unit and sensor on this model, some workshops replace the complete right rear hub bearing assembly. After replacement, run the "Wheel Speed Sensor Direction Learning" procedure with a diagnostic scanner, clear fault codes, and conduct straight-line and cornering road tests to confirm synchronous signals from all four wheels.
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BYD DTC AI Analysis

Destroyer 05: fault codes after wheel speed sensor swap

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While diagnosing another fault, the technician mistakenly swapped the left and right rear wheel speed sensors. Immediately after installation, the instrument cluster displayed an ESP fault. The scanner showed codes C051776 (right rear) and C051176 (left rear, indicating incorrect left rear sensor orientation). The technician realized he had installed them on the wrong sides. Comparing the two sensors revealed that although they looked identical, the magnetic pole bias direction at the sensor heads was opposite—designed to match the rotation direction of the left and right wheel bearing tone rings. With the sensors swapped, the detected signal phase was opposite to what the ECU expected, triggering the orientation error. Solution: Swap the left and right rear wheel speed sensors back to their correct sides. Clear the fault codes and check the four-wheel speed data to confirm all signals change synchronously with vehicle speed without abnormal jumps or delays. This case shows that wheel speed sensors on some newer BYD models have strict left/right distinctions and cannot be interchanged.
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Other Seal U 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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.