BYD ATTO 3 (e-Platform 3.0) C004900 Brake Fluid Level Below Normal Threshold

C004900 indicates that the brake fluid level has fallen below the expected threshold detected by the brake fluid level monitoring system. The fault affects the brake hydraulic system and may be triggered when the level sensor or associated control system detects insufficient fluid in the reservoir. The BYD ATTO 3 uses BYD’s e-Platform 3.0 architecture, with this generation introduced from 2022 and continuing onward.

Symptoms

• Brake warning message or warning light on the instrument cluster
• C004900 stored in the vehicle control system
• Low brake fluid level in the reservoir
• Brake pedal may feel different from normal
• Reduced confidence in braking performance
• Warning may appear intermittently on uneven roads if the fluid level is marginal
• ABS or brake-related warning messages may accompany the fault

Possible Causes

• Low brake fluid level
• Brake fluid leakage from the hydraulic system
• Worn brake pads causing the reservoir level to fall
• Faulty brake fluid level sensor
• Damaged or contaminated sensor connector
• Open or short circuit in the sensor wiring
• Reservoir or sensor installation fault
• Incorrect brake fluid level following previous brake service
• Brake hydraulic system fault

Diagnosis

Diagnosis should begin by verifying the actual brake fluid level and checking for visible evidence of leakage around the reservoir, brake lines, calipers, and other hydraulic components. The brake fluid level sensor, connector, wiring, and related control-system data should then be evaluated to determine whether C004900 represents a genuine low-fluid condition or an electrical/sensor fault. For New Zealand owners, confirming the underlying cause before replacing the level sensor can help avoid unnecessary repair costs.

Accurately diagnosing this fault often requires manufacturer testing procedures, wiring diagrams, connector pinouts, specifications, and system calibration information. Access to the factory service manual significantly reduces diagnostic time and helps prevent unnecessary parts replacement.

Applicable Years

2022, 2023, 2024, 2025, 2026, onwards

To order the correct OEM Service and Repair Manual for your BYD ATTO 3, submit your request using the form below and our team will provide the ordering details.