AU
C003108

This DTC indicates the ABS control unit detects an abnormal or completely lost signal input while monitoring the left front wheel speed sensor — Qin Plus

Braking System

This DTC indicates the ABS control unit detects an abnormal or completely lost signal input while monitoring the left front wheel speed sensor.

The wheel speed sensor (typically magnetic or Hall-effect) generates a pulse signal by monitoring the rotation of the tone ring on the half shaft or wheel hub.

Systems such as ABS, ESC, and EPB rely on this signal to calculate wheel speed.

The control unit sets C003108 when the signal voltage falls outside the threshold (<0.5V or >4.5V), the signal frequency is abnormal, or intermittent interruptions occur.

This fault prevents accurate detection of the left front wheel speed.

It triggers ABS failure, deactivates the ESC system, disables the automatic emergency braking system, and potentially affects the coordinated control of the energy recovery system.

On pure electric models such as the E5, it also affects motor torque distribution and coasting energy recovery smoothness.

The C003108 fault code on the Qin Plus indicates an abnormal or lost signal from the left front wheel speed sensor. This is a medium-severity fault that can disable ABS, ESC, and related braking or stability functions. Common causes include a failed wheel speed sensor or an incorrect sensor-to-tone-ring gap from wear, looseness, or deformation. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Left front wheel speed sensor failure: internal coil open circuit (magnetic type resistance: 1.2-1.6kΩ) or damaged Hall element, causing no signal output or insufficient output amplitude.
  • 2Abnormal sensor installation gap: Bearing wear, loose sensor retaining bolts, or mounting base deformation causes the gap between the sensor and the tone ring to exceed the standard value (0.3-1.2mm), reducing signal amplitude.
  • 3Wiring harness and connector fault: Tension during steering or driving over bumps breaks internal wires in the chassis wiring harness (commonly near the fender liner), water enters and oxidizes the connector, or a damaged shielding layer allows electromagnetic interference.
  • 4Reluctor ring fault: Metal shavings or mud/sand adhering to the reluctor ring surface (common after wading), deformed reluctor ring (tire lever damage during tire repair), missing teeth, or rusted tooth surfaces, causing signal waveform distortion.
  • 5ABS control unit internal fault: Damaged input-stage amplifier circuit or faulty A/D conversion module causes the system to misjudge normal signals as abnormal (confirm via process of elimination).
What To Do
  • 1
    Initial inspection: Raise the vehicle and visually inspect the left front wheel speed sensor for exterior damage. Inspect the wiring harness routing for abrasion or crush marks, and inspect the connector for looseness, water ingress, or oxidation.
  • 2
    Reluctor ring inspection: Rotate the left front wheel and inspect the reluctor ring for missing teeth, deformation, cracks, or attached foreign matter. Clean metal shavings and oil from the reluctor ring surface. Check the half-shaft bearing for excessive clearance (replace if radial play >0.5mm).
  • 3
    Circuit continuity test: Disconnect the ABS pump connector and sensor connector. Measure circuit continuity for the power wire (+12V), signal wire, and ground wire; resistance must be <1Ω. Measure wiring harness insulation to ground; resistance must be >10MΩ.
  • 4
    Sensor resistance/voltage test: The magnetic inductive sensor resistance must measure 1.2-1.6 kΩ (20°C). For the Hall sensor, with the key in the ON position, the supply voltage must measure 12V ± 0.5V, and the signal wire static voltage must measure 2.0-2.5V.
  • 5
    Dynamic signal test: Connect an oscilloscope or set a multimeter to the AC voltage range. Rotate the wheel. A magnetic inductive sensor should output >100mV AC voltage that increases with wheel speed; a Hall-effect sensor should output a 0-5V square wave signal.
  • 6
    Gap measurement and adjustment: Use a feeler gauge to measure the gap between the sensor and the tone ring tooth tip. Standard gap: 0.3-1.2 mm. If out of specification, check the sensor mounting bolt torque (typically 8-10 N·m), adjust the shim, or replace the sensor.
  • 7
    Component replacement verification: If the above checks are normal, substitute the left front wheel speed sensor with a known good part and road test the vehicle. If the fault clears, the sensor is faulty. If the fault persists, check the ABS pump.
Real-World Cases
BYD DTC AI Analysis

E5 sensor body aging caused intermittent signal loss

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Vehicle: 2019 BYD E5, 80,000 km. Symptoms: ABS light intermittent, especially on rough roads. Diagnostic tool read C003108 (current fault). Diagnosis: Sensor resistance measured 1.3 kΩ at rest but jumped to open circuit when tapping the body. Found dry solder joint on internal coil. Fix: Replaced left front wheel speed sensor (SK-3630100). Cleared codes and road-tested 20 km. ABS function normal.
BYD DTC AI Analysis

Qin Pro wiring harness connectors oxidized and corroded after water ingress

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Vehicle: BYD Qin Pro DM. Fault: Warning light constantly on. Symptoms: ABS and ESC lights illuminated simultaneously after wading through heavy rain. C003108. Diagnosis: Sensor power supply normal. Signal line voltage only 0.3V (abnormal). Removed left front fender inner harness connector; found mud and water residue inside with pins oxidized green. Repair: Cleaned connector with electronic cleaner, applied conductive paste, dried and reinstalled. Wrapped harness connector with waterproof tape and adjusted mounting position to prevent water ingress. Fault cleared.
BYD DTC AI Analysis

Excessive bearing clearance on Song Plus caused abnormal signal

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Vehicle: BYD Song Plus EV, 60,000 km. Symptoms: ESC warning light flashing above 80 km/h. Scanned DTC C003108 (historic). Diagnosis: Raised the vehicle. Rocked the left front wheel and found noticeable radial play in the wheel bearing (approx. 2 mm). Rotated the wheel and observed excessive variation in the gap between the sensor and tone ring. Signal was normal at low speed, but tone ring wobble caused signal loss at high speed. Resolution: Replaced the left front wheel hub bearing assembly (including tone ring). Reinstalled the sensor and adjusted the gap to 0.8 mm. No recurrence.
BYD DTC AI Analysis

Iron filings on E5 tone ring caused signal waveform distortion

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Vehicle: 2018 BYD E5, commercial vehicle. Symptoms: ABS warning light on, DTC C003108. ABS triggers early during braking (false activation). Diagnosis: Sensor and wiring tested normal. Disassembly revealed the reluctor ring coated with heavy brake dust and metallic debris, causing abnormal magnetic flux changes and noisy signal output. Fix: Thoroughly cleaned the reluctor ring surface and blew out the sensor head with compressed air. Inspected brake pads—severely worn, generating excessive dust. Replaced the brake pads. Fault resolved.
BYD DTC AI Analysis

Song Pro wiring harness wear causes intermittent open circuit

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Vehicle: BYD Song Pro, 40,000 km. Symptom: ABS warning light illuminates at full steering lock and extinguishes when straightened. Diagnosis: Repeatedly simulated full left lock. When the fault occurred, the sensor signal line showed infinite resistance to ground. Inspected the harness along the left front shock tower; the harness had stretched at full lock, with internal conductors partially fractured and only a few strands remaining. Resolution: Cut out the damaged section, repaired with soldered same-specification wire, rerouted clear of the steering sweep, and secured to the body bracket. Fault resolved.
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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.