AU
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.

The C055800 fault code on the Seal U indicates a mismatch in the right rear wheel speed sensor signal protocol, meaning the IPB braking control unit cannot correctly read wheel speed data. Severity is medium, as ABS, ESC, TCS, or emergency braking functions may be reduced. Common causes include a faulty wheel speed sensor or damaged, corroded, or poorly shielded wiring. The first recommended fix is to visit an authorised dealer. Typical repair cost data is available from 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Wheel speed sensor hardware fault: Poor thermal stability of the internal Hall element or processing chip distorts the output signal waveform at high temperatures or high speeds, causing protocol verification failure.
  • 2Wiring harness and connector fault: Oxidized or recessed sensor connector pins, or damaged wiring harness shielding causing electromagnetic interference that distorts the signal during transmission.
  • 3Mechanical installation issue: Air gap between the sensor and magnetic encoder ring (tone ring) exceeds the standard range (0.3-1.2mm), or a deformed, contaminated, or demagnetized encoder ring causes abnormal signal amplitude.
  • 4Software/hardware version mismatch: The replacement wheel speed sensor part number does not match the hardware version required by the vehicle VIN (e.g., different output pulse count), causing the IPB to detect a protocol error.
  • 5IPB control unit internal fault: Abnormal sampling resistor or filter capacitor in the control unit input circuit causes misinterpretation of normal signals (less common)
What To Do
  • 1
    Initial diagnostic scan: Use VDS or a dedicated diagnostic tool to read the complete fault codes and freeze frame data. Confirm if C055800 is a current fault and record environmental parameters such as vehicle speed and temperature when the fault occurred.
  • 2
    Visual and connection inspection: Check the right rear wheel speed sensor connector (usually located near the rear suspension) for looseness, water ingress, or oxidation; check the wiring harness sheath for damage, focusing on wear-prone areas under the chassis; check the magnetic encoder ring for cracks, deformation, or attached foreign matter.
  • 3
    Electrical parameter measurement: Disconnect the sensor connector. Measure the sensor supply voltage (should be 12V±0.5V) and ground resistance (should be less than 1Ω). Measure the resistance and voltage of the sensor signal wire to ground. Use an oscilloscope to monitor the sensor output waveform and check for noise, abnormal amplitude, or duty cycle drift.
  • 4
    Mechanical clearance check: Use a feeler gauge to measure the air gap between the sensor end face and the encoder ring. The standard value is typically 0.3-1.2mm (refer to the repair manual for exact specifications). Check if the encoder ring radial runout exceeds the limit.
  • 5
    Component replacement and matching: If diagnostics confirm a sensor fault, replace the sensor with a genuine part (match the part number to the VIN). Install the new sensor and tighten to the specified torque (usually 8±1N·m). On some models, use the diagnostic tool to execute the 'Wheel Speed Sensor Zero-Point Calibration' or 'ABS System Configuration' procedure.
  • 6
    Verification test: Clear the fault code and perform a road test (including low-speed, medium-speed, high-speed, and steering conditions). Monitor the data stream to verify the right rear wheel speed signal synchronizes with the other three wheels without sudden jumps. Confirm the fault indicator remains off.
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
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.