What Causes the ABS Light to Illuminate in the Octavia?

[KingDella]

ABS light illumination can occur in various states, each with different causes and solutions, as detailed below: State 1: ABS warning light remains constantly on (most common). Cause 1: The ABS wheel speed sensor's sensing area is covered by dirt, mud, or other contaminants, affecting its ability to detect the corresponding speed signal. This prevents the ABS control unit from determining the vehicle speed or wheel slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean the contaminants from the wheel speed sensor and adjust the gap between the sensor and the tone ring to restore normal function. Cause 2: Poor signal transmission due to loose system wiring connections or faulty ABS relay contacts. Solution: Inspect wiring connections and re-secure any loose connections. State 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple electrical components are in use, the battery voltage may drop below 10.5V. As engine speed increases and voltage rises, the ABS light turns off. This may also indicate insufficient power supply voltage to the ABS system due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; examine power supply components (e.g., voltage relay or poor power contacts). State 3: ABS warning light stays on after engine start until engine IGFF turns it off. Cause: Poor grounding connection of ABS hydraulic valve body; faulty wiring connector of ABS hydraulic valve body; ABS control unit malfunction. Solution: Loosen and retighten the hydraulic valve body ground screw, cleaning contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR control unit. State 4: ABS warning light illuminates during high-speed driving. Cause: The ABS control unit detects excessive speed difference between rear and front wheels; incorrect tire or wheel rim specifications. Solution: Refer to vehicle tire and wheel rim specifications listed on the fuel filler cap label. State 5: ABS warning light intermittently flashes. Cause: Improper brake light switch adjustment; internal brake light contact failure. Solution: With engine running, depress brake pedal, manually push brake switch linkage downward fully, then release pedal to complete self-positioning; replace brake light switch if necessary. When the ABS warning light is illuminated, it's advised to avoid continued driving as this indicates a fault in the anti-lock braking system. During emergency braking, wheel lock-up may cause loss of vehicle control and skidding, preventing the driver from decelerating or adjusting trajectory, posing significant safety risks.