What causes the Octavia's tire pressure ABS warning light to come on?

[DiIvan]

ABS warning lights can indicate various conditions, each with different causes and solutions, as detailed below: Condition 1: ABS warning light stays on (most common). Cause 1: The ABS speed sensor's sensing area is covered by dirt, mud, or other contaminants, affecting its ability to detect the vehicle's speed signal. This prevents the ABS computer from determining the speed and wheel slip rate, thus failing to issue appropriate commands to adjust braking. Solution: Clean the contaminants from the speed sensor and adjust the gap between the sensor and the signal ring to restore normal function. Cause 2: Poor signal transmission due to loose system wiring connections or faulty ABS relay contacts. Solution: Check all wiring connections and reconnect any loose parts. Condition 2: ABS warning light intermittently comes on but turns off when accelerating. Cause: Battery voltage drops below 10.5V when multiple electrical devices are in use. The ABS warning light turns off as engine speed increases and voltage rises. Low system supply voltage due to poor terminal contact or grounding issues. Solution: Check battery specific gravity, charging system, and power supply (e.g., voltage relay or poor power contact). Condition 3: ABS warning light stays on after engine start and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact of the ABS hydraulic valve body; loose wiring connections at the ABS hydraulic valve body; ABS computer malfunction. Solution: Loosen and retighten the grounding screws on the hydraulic valve body, cleaning contact surfaces if necessary. Check for enlarged connector gaps. Replace the ABS or ABS/ASR computer if needed. Condition 4: ABS warning light comes on during high-speed driving. Cause: The ABS computer detects a significant discrepancy between rear and front wheel speeds. Incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, typically found on the sticker near the fuel tank cap. Condition 5: ABS warning light intermittently comes on. Cause: Improper adjustment of the brake light switch; poor internal contact in the brake light. Solution: With the engine running, press the brake pedal and manually push the brake switch lever down fully, then release the pedal to reset its position. Replace the brake light switch if necessary. If the ABS warning light is on, it is advisable not to continue driving. An illuminated ABS light indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels can cause the vehicle to skid uncontrollably, preventing the driver from slowing down or adjusting the vehicle's trajectory, posing significant safety risks.