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C003504

DTC C003504 indicates a right front wheel speed sensor (RF Wheel Speed Sensor) circuit or signal abnormality, specifically low sensor supply voltage, signal voltage out of range, or compromised circuit integrity — Qin Plus

Braking System

DTC C003504 indicates a right front wheel speed sensor (RF Wheel Speed Sensor) circuit or signal abnormality, specifically low sensor supply voltage, signal voltage out of range, or compromised circuit integrity.

In the BYD ABS/ESP system, this fault prevents the control unit from obtaining an accurate right front wheel speed signal and triggers limp mode.

Effects include: ABS function disabled, ESP deactivated, EBD malfunction, automatic emergency braking (AEB) function limited, regenerative braking efficiency reduced or disabled, and cruise control unavailable.

This DTC is a hard fault.

The control unit triggers this code upon continuously detecting the abnormality with the ignition switch in the ON position or while driving.

The C003504 fault code on the Qin Plus indicates an abnormal right front wheel speed sensor circuit or signal, usually causing ABS/ESP faults and limp mode. Severity is medium because braking support functions such as ABS, EBD, AEB, regenerative braking, and cruise control may be limited or disabled. Common causes include a failed wheel speed sensor or damaged, corroded, or loose wiring/connectors. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Wheel speed sensor failure: Internal coil open or short circuit, abnormal electromagnetic sensor resistance (normal: 1.0-1.5kΩ), abnormal Hall sensor power supply, or damaged internal circuit, resulting in weak or distorted signal output.
  • 2Wiring and connector issues: Sensor plug oxidation, water ingress corrosion, or loose pins; wiring harness insulation wear causing a short to ground or intermittent open circuit; engine compartment high temperatures causing the wiring harness to age and crack, especially where a loose retaining clip on the right front longitudinal rail allows the harness to rub against the vehicle body.
  • 3Mechanical installation and clearance faults: Sensor-to-tone ring (reluctor ring) clearance is too large (standard: 0.3-1.2 mm) or too small, causing rubbing; a loose or damaged right front wheel bearing causes tone ring radial runout to exceed tolerance (>0.1 mm), preventing the sensor from detecting a stable signal.
  • 4Signal tone ring contaminated or damaged: Brake dust, iron shavings, or mud and water adhering to the tone ring surface; broken, missing, or deformed tone ring teeth (common after accident repairs or on vehicles with prolonged water exposure), causing irregular magnetic flux changes.
  • 5ABS pump assembly internal fault: Damage to the right front wheel speed signal processing circuit inside the ABS control unit, a burnt sampling resistor, or a poor ground connection causes the system to falsely detect a sensor circuit fault.
What To Do
  • 1
    Pre-inspection and fault confirmation: Connect the VDS or OEM diagnostic tool to read all fault codes. Confirm whether C003504 is an Active or History fault. Check the freeze frame data and record parameters such as vehicle speed and voltage when the fault occurred. Clear the fault codes and perform a road test to confirm fault reproduction conditions.
  • 2
    Visual and mechanical inspection: Raise the vehicle and check the right front wheel speed sensor installation. Verify bolt torque (usually 8-12 N·m). Inspect the sensor tip for metal filings, oil contamination, or physical damage. Check signal tone ring integrity and clean the tone ring surface. Manually rock the right front wheel to check bearing play and verify no radial or axial looseness.
  • 3
    Electrical parameter measurement: Disconnect the sensor connector and measure sensor resistance (magnetic type: 1.0-1.5kΩ; Hall type requires power supply test). Measure the harness-side supply voltage (12V±0.5V, ignition ON) and ground wire resistance (<1Ω). Use an oscilloscope to check the signal waveform. Confirm the waveform is a sine wave (magnetic type) or square wave (Hall type) with normal amplitude.
  • 4
    Harness continuity and insulation test: Test continuity from the sensor connector to the ABS pump ECU connector (resistance <1Ω). Measure signal wire insulation resistance to ground and to power (should be >10MΩ). Inspect the harness securing condition at wear-prone areas, such as the right front longitudinal beam in the engine compartment and the fender liner. Repair damaged sections and install corrugated conduit.
  • 5
    Component replacement and verification: If measurements confirm a faulty sensor, replace it with an OEM right front wheel speed sensor (distinguish between magnetic inductive and Hall types; E5 mostly uses the Hall type). If the bearing has excessive play, replace the wheel hub bearing assembly. After repair, clear the fault codes. Calibrate the wheel speed sensor (if required by the system). Perform a 5-10 km/h low-speed driving test to confirm synchronization of all four wheel speed signals. Finally, perform an ABS/ESP dynamic road test.
Real-World Cases
BYD DTC AI Analysis

E5: Sensor contamination and connector oxidation caused abnormal signal

✓
A 2018 BYD E5 with 80,000 km had constant ABS and ESP warning lights on the instrument panel. The scan tool read fault code C003504. Technicians removed the right front wheel speed sensor and found the magnetic head coated in iron filings and brake dust. The sensor plug pins showed white oxidation. They cleaned the sensor head and tone ring with carburetor cleaner, sanded the plug pins with fine sandpaper to remove the oxidation, applied conductive grease, and reinstalled. They cleared the fault codes and road tested; the wheel speed signal returned to normal and the warning lights went out. This fault is relatively common in vehicles driven through water or used long-term in humid conditions.
Original source ↗
BYD DTC AI Analysis

Song Pro: Excessive play in right front wheel bearing causing intermittent fault

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2019 BYD Song Pro DM, 120,000 km. Dashboard intermittently displayed "Check ESP System". Scan tool showed C003504 as an intermittent fault. Data stream showed right front wheel speed signal occasionally dropping to zero or deviating more than 5 km/h from other wheels. Raised the vehicle and found obvious radial play in the right front wheel bearing (approximately 2 mm), causing the reluctor ring to oscillate radially relative to the sensor during rotation. Replaced the right front hub bearing assembly and readjusted the sensor installation clearance to 0.8 mm. Fault eliminated. Replacing the sensor alone won't fix this type of mechanical wear.
BYD DTC AI Analysis

Wiring harness chafing causes intermittent open circuit in E5 EV

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A BYD E5 taxi with 150,000 km on the clock failed to enter READY mode, the instrument cluster displaying a brake system fault. DTC C003504 (current fault) present. Inspection found the RH front wheel speed sensor wiring harness had come loose from its retaining clip at the RH front longitudinal member in the engine bay. The harness had rubbed against the body panel, wearing through the insulation and breaking the copper cores of both internal wires, causing an intermittent open circuit. We stripped back the harness, re-soldered the broken conductors, insulated them with heat-shrink tubing, properly re-routed and secured the harness, and fitted protective corrugated conduit. The vehicle returned to normal after repair, with regenerative braking function restored.
Original source ↗
BYD DTC AI Analysis

Qin EV sensor body aging failure

✓
2018 BYD Qin EV450, 60,000 km. ABS warning light constantly on. Scanned with a diagnostic tool and found DTC C003504—active static fault. Tested the right front wheel speed sensor: power supply normal at 12.4 V, but no pulse signal at the output. Removed the sensor and measured resistance; open circuit (infinite). Internal coil break confirmed. Replaced with an OEM right front wheel speed sensor (part number: 3630420-XXX). Executed the 'sensor calibration' procedure with the scan tool, cleared the codes and road tested. All four wheel speed signals consistent; ABS function restored.
BYD DTC AI Analysis

Tone ring deformed after accident repair, causing signal distortion

✓
A BYD e5 that had undergone right-front collision repairs at a dealership traveled approximately 1,000 km before the ESC warning light illuminated, logging code C003504. Inspection found the replacement right-front steering knuckle assembly (including the signal reluctor ring) installed during the accident repair was slightly deformed, causing reluctor ring radial runout of 0.3 mm (specification <0.1 mm). The sensor detected a signal, but waveform amplitude was unstable, so the ABS pump flagged a circuit fault. Replaced the steering knuckle and hub bearing assembly with a qualified unit, calibrated reluctor ring radial runout to within 0.05 mm using a dial gauge, and cleared the fault.
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.