AU
C003204

DTC C003204 indicates an electrical fault in the left front wheel speed sensor (WSS) circuit within the BYD ABS system — Qin Plus

Braking System

DTC C003204 indicates an electrical fault in the left front wheel speed sensor (WSS) circuit within the BYD ABS system.

This variable reluctance or Hall-effect sensor supplies the wheel speed signal to the ABS/ESC control unit.

The control unit sets this code upon detecting an open circuit, short to ground, short to power, or abnormal signal interruption in the sensor circuit.

In BYD new energy vehicles, this fault impairs normal ABS/ESP operation.

It also limits regenerative braking, disables cruise control, disrupts four-wheel-drive torque distribution (if applicable), and may trigger a "Check braking system" warning.

Because electric vehicles rely on wheel speed signals to calculate coasting energy recovery and estimate driving range, this fault reduces driving smoothness and causes inaccurate range displays.

In severe cases, it triggers false ABS activation or complete ABS failure, compromising driving safety.

The C003204 fault code on the Qin Plus indicates a medium-severity electrical problem in the left front wheel speed sensor circuit. This can affect ABS/ESP operation, regenerative braking, cruise control, and braking warnings. Common causes include damaged wiring near the steering or suspension, or a loose or corroded sensor connector. The recommended fix is to have the system inspected and repaired by an authorised dealer. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Left front wheel inner wiring harness wear: Long-term bending at the steering knuckle or suspension movement points damages the harness insulation, causing an intermittent open circuit or short to ground.
  • 2Sensor connector oxidized or loose: Water exposure or damp environments cause connector pin oxidation and corrosion, or a damaged locking tab causes excessive contact resistance.
  • 3Sensor failure: Internal coil open circuit, magnetic core demagnetization, or Hall element aging causes abnormal or no signal output.
  • 4Tone ring (magnetic encoder) fault: Tone ring on the half shaft or wheel hub bearing is deformed, missing teeth, contaminated with iron filings or dirt, or the installation gap exceeds tolerance (standard 0.3-1.2 mm).
  • 5ABS pump ECU connector fault: control unit terminal pins backed out or corroded, or internal sampling circuit damaged (low probability, but requires inspection)
What To Do
  • 1
    Visual inspection: Check the left front wheel speed sensor connector for looseness, oxidation, or water ingress, and inspect the wiring harness at the steering knuckle and control arm for wear, damaged insulation, or pinch marks.
  • 2
    Diagnostic tool check: Use VDS or a generic diagnostic tool to read the fault code status (current/history). Check the data stream for abnormal left front wheel speed (reads 0, fluctuates, 255 km/h, or differs significantly from the other three wheels).
  • 3
    Resistance measurement: Disconnect the sensor connector and measure the resistance across the sensor terminals. Normal range for magnetic inductive type: 1.0-1.6 kΩ. For Hall effect type, refer to the manual. Replace the sensor if the resistance is out of range.
  • 4
    Power supply check: Turn ignition ON. Measure voltage at the power supply terminal of the wiring harness side connector. Voltage must be 12V±0.5V. If abnormal, check the fuse and power supply circuit.
  • 5
    Signal test: Use an oscilloscope or multimeter set to DC voltage. Rotate the wheel and measure the signal wire voltage. The voltage should show a 0-5V pulse. A fixed voltage or no change indicates a faulty sensor or tone ring.
  • 6
    Circuit continuity test: Disconnect the ABS pump ECU connector and sensor connector. Measure the continuity of the signal, ground, and power wires (should be <1Ω) to check for open circuits.
  • 7
    Insulation test: Measure the insulation resistance of the signal wire to ground and to power. Resistance must be >10MΩ to prevent intermittent short circuits from causing abnormal signals.
  • 8
    Reluctor ring inspection: Inspect the magnetic reluctor ring on the half shaft or wheel hub bearing for deformation, missing teeth, or dirt. Use a feeler gauge to verify the gap between the sensor and the reluctor ring is 0.3-1.2 mm.
  • 9
    Road test verification: After repair, clear the fault code. Monitor the data stream while driving to verify four-wheel synchronization. Perform an emergency braking test to confirm normal ABS/ESP function.
Real-World Cases
BYD DTC AI Analysis

BYD Song Pro left front wheel speed sensor signal fault

✓
Symptoms: ABS and ESP warning lights lit together. "Clunking" noise during low-speed cornering; speedometer showed intermittent fluctuation. Diagnosis: Launch X431 scan pulled DTC C003204. Sensor resistance measured 1.2 kΩ (normal). Signal voltage jumped around when rotating the wheel, indicating intermittent open circuit. Found oxidation inside the connector. Fix: Cleaned sensor connector contacts and applied conductive grease. Fault persisted, so replaced left front wheel speed sensor assembly. Cleared codes and road-tested 10 km; live data showed normal wheel speed signals.
Original source ↗
BYD DTC AI Analysis

BYD Qin DM left front wheel speed sensor circuit fault

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Symptoms: ABS warning light stayed on after startup. ABS engaged prematurely during braking with pedal kickback. Hybrid system displayed "Check ESP System". Regenerative braking limited. Diagnosis: VDS scan tool read DTC C003204. Live data showed left front wheel speed at 0 km/h while the vehicle was moving. Inspection found the left front inner wiring harness chafed against the steering knuckle; damaged insulation caused an intermittent short to ground. Continuity testing confirmed an intermittent open in the white signal wire. Resolution: Repaired the damaged harness with heat-shrink tubing. Re-routed and secured the harness to prevent contact with the steering knuckle. Cleared fault codes and performed the ABS pump bleed. Road test confirmed the fix.
Original source ↗
BYD DTC AI Analysis

BYD Tang Petrol: Left front wheel speed sensor performance fault

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Symptoms: ESP warning light flickers intermittently above 80km/h; 4WD mode automatically disengages with "4WD system fault" warning; braking distance noticeably increased. Diagnosis: Dedicated diagnostic tool retrieved DTC C003204 (Performance/Range fault). Live data showed a consistent 5-8km/h deviation between left front wheel speed and the other three wheels. Sensor installation gap measured 1.8mm (exceeds 0.3-1.2mm specification). Cleaned iron debris from sensor head; deviation persisted. Fix: Replaced OEM left front wheel speed sensor. Adjusted sensor-to-tone ring gap to 0.8mm using feeler gauges. Road test confirmed all four wheel speed signals synchronised in live data; ESP and 4WD functions returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD F3: Intermittent signal loss from left front wheel speed sensor

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Symptoms: ABS warning light intermittent with no pattern, triggers easily on rough roads and may clear on smooth surfaces. No drivability issues. Diagnosis: Generic scan tool retrieved DTC C003204 (history). During dynamic testing, manually rotating the left front wheel caused the data stream to intermittently spike to 255 km/h then drop to zero. Found the sensor connector lock tab damaged and connection loose. Sensor supply voltage measured 8-12V fluctuation (spec: stable 12V). Solution: Replaced the sensor plug (with wiring harness connector). Checked ABS pump ECU supply circuit and found oxidation at the battery negative ground point. Cleaned and tightened the ground cable. Fault cleared. Monitored one week with no recurrence.
Original source ↗
BYD DTC AI Analysis

BYD e5 Pure Electric — Left front wheel speed sensor signal unreliable

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Symptoms: Dashboard displayed "Check Brake System." Regenerative braking weakened significantly, cruise control failed to activate, and coasting distance increased with a sensation of neutral coasting. Diagnosis: BYD dedicated diagnostic tool retrieved DTC C003204 (implausible signal). Live data showed spike interference and irregular waveform on the left front wheel speed signal. Inspection found no physical damage to the sensor or harness, but the left front wheel bearing tone ring showed minor distortion with partially missing teeth. Resolution: Replaced the left front wheel bearing assembly (including magnetic tone ring) and preventively replaced the left front wheel speed sensor. Calibrated the ESP system and performed sensor matching. Road test confirmed regenerative braking and cruise control returned to normal.
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.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.