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C003408

DTC C003408 indicates the ABS control unit detects an abnormal right front wheel speed sensor (WSS) signal, specifically signal amplitude out of range, signal interruption, or excessive signal noise — Atto 3

Braking System

DTC C003408 indicates the ABS control unit detects an abnormal right front wheel speed sensor (WSS) signal, specifically signal amplitude out of range, signal interruption, or excessive signal noise.

On models such as the BYD E5, this sensor typically features a magnetic induction (passive inductive) design, generating a sine wave signal via the alternating magnetic field produced by the rotating tone ring (target wheel).

If the signal voltage drops below the threshold (typically <0.1V), experiences interruption, or exhibits waveform distortion, the ABS/ESC system cannot accurately calculate the right front wheel angular speed.

This disables anti-lock control, Electronic Brakeforce Distribution (EBD), the Traction Control System (TCS), and the energy recuperation braking coordination strategy.

This classifies as a hard fault or an intermittent signal fault.

The instrument cluster illuminates the ABS/ESC warning light, and some models limit energy recuperation strength and switch to a conventional hydraulic braking priority mode.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Worn wiring harness on BYD E5 right front wheel speed sensor causing intermittent signal loss

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Symptoms: ABS/ESC warning lights intermittently illuminated on rough roads. Fault code C003408 (current/historical). Diagnosis: Lifted the vehicle. Found the right front wheel speed sensor wiring harness chafing against the suspension arm near the steering knuckle. Damaged insulation caused intermittent short between signal wire and shield. Static resistance read normal, but fluctuated when moving the harness. Resolution: Repaired the wiring harness (re-wrapped and re-routed to clear moving parts) and replaced the damaged sensor connector. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Song Multi-System Fault Troubleshooting (Poor Wiring Connection Reference Case)

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Symptoms: While driving, the instrument cluster suddenly displayed multiple warnings: "Check Engine System", "ABS System", "Network", and "Braking System". Diagnosis: VDS scan showed the ESP module reporting CAN data errors. Continuity testing found an open circuit between the GJB06/BJG06 connectors, isolated to a break between pin 16 of AJB01 and pin 27 of WA01(A). Although this case primarily involved the accelerator pedal wiring, the troubleshooting approach for poor contact—measuring connector continuity and checking for backed-out pins—parallels that for wheel speed sensor faults. Solution: Replaced the engine wiring harness (including related connectors). This restored communication and cleared all system faults.
Original source ↗
BYD DTC AI Analysis

Backed-out sensor connector pin caused signal fault in BYD Han EV

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Symptoms: Instrument cluster displayed brake system warning light. Scan tool retrieved wheel speed DTCs (C0034 series). Diagnosis: Right front wheel speed sensor connector had backed-out terminals, causing high contact resistance and signal interruption. Harness continuity measured unstable resistance. Resolution: Reseated terminals to proper position and confirmed locking tabs engaged. Remeasured harness continuity: <0.5Ω. Cleared DTCs and road tested. Wheel speed signal returned to normal.
Original source ↗
BYD DTC AI Analysis

Deformed tone ring on right front wheel of E5 caused abnormal signal waveform

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Symptoms: ABS activates prematurely during braking (pedal kickback). No warning light on the dash, but history code C003408 stored. Diagnosis: Checked the right front wheel speed sensor signal with a scope. Found significant dropouts and amplitude spikes in the waveform. Disassembly revealed the tone ring was locally deformed from a previous bottom-out impact, with bent teeth. Solution: Replaced the right front hub bearing assembly (includes tone ring), cleaned the sensor magnetic tip, and measured the air gap at 0.8mm after installation (within spec). Road test confirmed normal ABS operation.
BYD DTC AI Analysis

Right front wheel speed sensor connector oxidised and shorted after water ingress

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Symptoms: After driving through water, the ABS warning light remained on with DTC C003408 stored. Diagnosis: Inspection found internal water in the right front wheel speed sensor connector. The pins showed green oxidation, dropping resistance between the signal wire and ground to approximately 200Ω. Resolution: Cleaned the connector thoroughly with electronic contact cleaner, dried it, then applied conductive grease and waterproof sealant. If oxidation is severe, replace the connector or sensor assembly. Check the wiring harness seal integrity.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.