AU
C003500

DTC C003500 indicates the IPB (Intelligent Integrated Braking System) detected an abnormal supply voltage to the right front wheel speed sensor — Seal U

Braking System

DTC C003500 indicates the IPB (Intelligent Integrated Braking System) detected an abnormal supply voltage to the right front wheel speed sensor.

On BYD e-Platform 3.0 and DM-i models, the wheel speed sensor typically uses a 12V DC supply (some earlier models use a 5V reference voltage).

The IPB module identifies faults by monitoring the supply circuit voltage.

The IPB sets this code when it detects a supply voltage below 9V (undervoltage), above 16V (overvoltage), or a complete open circuit (0V) lasting longer than the set threshold (typically 200ms).

This fault causes a loss of the right front wheel speed signal.

The IPB forcibly disables the ABS, ESC, EHB (Electro-Hydraulic Braking), and automatic emergency braking functions.

The vehicle enters limp mode and multiple system warning lights illuminate on the instrument cluster, severely compromising driving safety.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right front wheel speed sensor power supply circuit short to ground or open circuit: Frequent front wheel steering chafes the wiring harness against the fender liner or suspension control arm, exposing the copper core and shorting to body ground, or prolonged bending causes an internal break.
  • 2IPB control module internal power supply circuit fault: A damaged internal DC-DC converter or MOSFET driver chip in the IPB causes abnormal power supply output to the right front channel, often triggering other wheel speed sensor power supply fault codes.
  • 3Internal short circuit in the wheel speed sensor: Aging and breakdown of the internal sensor coil insulation or a damaged Hall element causes excessive current in the power supply circuit, triggering IPB overcurrent protection to cut off the power supply.
  • 4Poor contact or water ingress at the wiring harness connector: An aged seal ring on the right front wheel speed sensor connector (located near the shock absorber) allows internal oxidation after car washing or wading, increasing contact resistance (>5Ω) and causing a voltage drop.
  • 5Battery or main power supply fault: discharged 12V battery, alternator regulator fault causing system voltage fluctuations, or loose main body ground cable causing reference potential drift.
What To Do
  • 1
    Fault confirmation and freeze frame retrieval: Use the VDS2000/3000 diagnostic tool to read the complete fault codes. Confirm whether C003500 is a current fault (Class A) or a history fault (Class B). Record freeze frame data from the time the fault occurred, including vehicle speed, voltage, and temperature. Clear the fault codes and perform a road test to verify if the fault recurs.
  • 2
    Sensor supply voltage static measurement: Disconnect the right front wheel speed sensor connector (2-pin or 3-pin), turn the ignition switch to ON, and use a multimeter in DC voltage mode to measure the voltage between the connector-side supply pin (usually pin 1, yellow/red wire) and ground. The normal value is 12V±0.5V (battery voltage). If the voltage is abnormal (0V, below 9V, or above 16V), the fault lies in the wiring harness or the IPB side.
  • 3
    Harness continuity and insulation test: Turn off the ignition and disconnect the IPB module connector (located near the engine compartment firewall, 40-pin or 52-pin connector). Use a multimeter to measure the resistance of the power supply circuit between the IPB connector and the sensor connector (should be <1Ω), and measure the insulation resistance of this circuit to ground (should be >10MΩ). Inspect the harness sheath near the front wheel arch liner and steering knuckle for damage.
  • 4
    Load and short circuit test: Reconnect the sensor and connect a current clamp in series at the IPB module end to monitor the supply circuit current. Normal static current should be <15 mA. If the current is >50 mA or the voltage returns to normal after disconnecting the sensor, the sensor has an internal short circuit. Replace the right front wheel speed sensor (part number usually 3620100-XX or 3630100-XX series).
  • 5
    IPB module power supply output verification: If wiring harness measurements are normal (good continuity, normal insulation, sensor replaced) but the fault persists, measure the power supply output voltage at the corresponding IPB module pin. If the IPB output is abnormal while other wheel channels are normal, diagnose an internal IPB drive circuit fault and replace the IPB assembly (requires brake system bleeding and calibration).
  • 6
    Repair verification and system calibration: After repairing or replacing the faulty component, clear the fault code and test the wheel speed sensor signal waveform (use an oscilloscope to observe the amplitude of the sine or square wave signal). Verify the right front wheel speed synchronizes with the other three wheels. Finally, perform an online calibration of the IPB system (in VDS, select 'Intelligent Integrated Braking System' → 'Special Functions' → 'Sensor Calibration'). Confirm the fault code does not return and the ABS/ESC warning lights turn off.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i right front wheel speed wiring harness worn and shorted

✓
At 23,000 km, the dashboard simultaneously illuminated the ABS, ESP and automatic emergency braking warning lights. Scanned and found active DTC C003500. Raised the vehicle and found the right front wheel speed sensor wiring harness insulation worn at the connector; the copper core was touching the steering knuckle and shorting to ground. The short circuit current triggered IPB protection and cut the supply voltage. Wrapped the damaged harness, re-secured the routing to avoid suspension interference, and replaced the damaged sensor connector. After the repair, calibrated the IPB and the system returned to normal.
BYD DTC AI Analysis

Han EV IPB internal driver chip failure caused abnormal power supply to multiple wheel speed sensors

✓
After water ingress, the vehicle stored DTCs C003500 and C003100 (left front) for multiple wheel speed sensor power supply faults. Voltage measured 0V at all four wheel speed sensors. IPB power supply fuse and main power tested normal. Diagnosed as internal IPB power supply module (BTS724G driver chip) burned out from water ingress. The IPB is a highly integrated module (integrating EHB electronic hydraulic brake control) and the circuit board could not be repaired separately. Replaced the IPB assembly, bled the system using a brake fluid filling machine, and performed ESC sensor calibration and brake line pressure calibration via VDS. Fault resolved.
BYD DTC AI Analysis

Seal right front wheel speed sensor internal short circuit

✓
At 800 km, the ESC warning light came on intermittently with DTC C003500. The fault occurred more frequently when cold and cleared when warm. Supply voltage measured 3.2 V during the fault (normal: 12 V), returning to 12 V after unplugging the sensor. Internal Hall element or inter-turn short in the sensor coil; low insulation resistance when cold pulled the voltage down. Replaced the right front wheel speed sensor (magnetic or Hall type per configuration). No recurrence after one week of monitoring.
BYD DTC AI Analysis

Qin PLUS DM-i wheel speed sensor connector corroded from water ingress

✓
The warning light came on after washing the vehicle, logging DTC C003500. Inspection found green copper corrosion inside the right front wheel speed sensor connector. A degraded seal allowed water into the terminals. Terminal oxidation increased contact resistance to 8Ω. The IPB detected excessive supply voltage drop (only 7V at the sensor, below the 9V operating threshold), triggering the fault. Cleaned the connector terminals, applied conductive grease, replaced the waterproof seal, and restored contact resistance to 0.3Ω. Fault resolved.
BYD DTC AI Analysis

False alarm triggered by discharged 12V battery in Dolphin

✓
Owner started the vehicle after it sat parked for one week. Dashboard showed brake system fault. Scan revealed DTC C003500 and related communication faults. Battery voltage measured 10.8V, SOH at 65%. The IPB misinterprets sensor power supply faults when voltage drops below 11V. Replaced the 12V battery (L2-400 or EFB start-stop type), charged fully, and cleared codes. All systems returned to normal. Rule out power supply issues before investigating sensors.
Other Seal U 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.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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.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.
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.