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C055800

DTC C055800 indicates the IPB (Integrated Intelligent Braking System) control unit detects a mismatch between the digital signal protocol from the right rear wheel speed sensor (WSS) and the system preset standard — Seal U

Braking System

DTC C055800 indicates the IPB (Integrated Intelligent Braking System) control unit detects a mismatch between the digital signal protocol from the right rear wheel speed sensor (WSS) and the system preset standard.

Specifically, the sensor PWM (pulse-width modulation) or square-wave signal exceeds calibrated thresholds for waveform characteristics, duty cycle, frequency range, or voltage amplitude, preventing the control unit from correctly interpreting wheel speed data.

Unlike a simple signal loss (open circuit), this protocol-level communication mismatch indicates an incompatible sensor hardware version, signal distortion, or EMC interference.

When this fault triggers, wheel speed-dependent systems (ABS, ESC, TCS) enter a degraded mode.

On some models, the fault disables the automatic emergency braking system or limits vehicle speed.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Oxidized right rear wheel speed sensor connector on Tang DM caused signal protocol error

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ESP warning light comes on intermittently while driving; the cluster displays "Check ESP System". Speedometer needle occasionally jumps, with symptoms worse on rough roads. VDS2000 scan retrieved DTCs C055800 and C003A00. Found internal pin oxidation in the RH rear wheel speed sensor connector; measured sensor resistance at 1.8 kΩ (normal 1.5–2.5 kΩ); reluctor ring slightly deformed. Replaced RH rear wheel speed sensor (part number: 3635100-XXX), cleaned connector and applied conductive grease, straightened deformed reluctor ring section, and torqued sensor to 8 N·m. Cleared faults and road-tested 30 km; no recurrence.
BYD DTC AI Analysis

Damaged wheel speed sensor wiring harness on Song Pro causing protocol error faults

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ABS warning light stays on after startup. ABS triggers falsely during normal driving with pedal kickback, and the speed display is erratic. Scan tool showed DTCs C055800 and C055500 (multi-wheel protocol errors). Lifted the vehicle and found the wheel speed sensor wiring harness protective sleeve damaged underneath, with the signal wire shielding exposed and damaged, causing electromagnetic interference while driving. Repaired the harness, resoldered the shielding and wrapped it with waterproof tape, replaced the damaged sleeve, and replaced the right rear sensor for reliability. After repair, checked all four wheel speed signal waveforms with an oscilloscope, confirming no interference. Fault resolved.
BYD DTC AI Analysis

Qin Pro right rear wheel speed sensor thermal stability fault

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At speeds over 80km/h, ESP and ABS warning lights lit up simultaneously and the speedometer instantly dropped to zero. Lights went out after lifting off the throttle. Scan tool showed intermittent historical fault C055800. Checked connector pins—no retraction. Supply voltage 12V, normal. Oscilloscope monitoring caught the right rear wheel speed sensor signal amplitude fluctuating abnormally above 80km/h, dropping from the normal 5V peak-to-peak to below 2V. Faulty internal Hall element thermal stability. Fix: Replaced right rear wheel speed sensor assembly, air gap set to 0.8mm (within spec). Post-repair high-speed road test: 100km continuous driving, no fault codes.
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.