If your vehicle is showing spongy or soft clutch pedal, here are the most likely causes and the parts you'll need to fix each one.
Air compresses easily compared to hydraulic fluid, leading to a spongy pedal. This is often caused by improper bleeding after recent repairs or letting the fluid reservoir run dry.
Internal seals inside the master cylinder can wear out, allowing fluid to bypass the piston. This prevents the system from building full pressure when you press the pedal.
The slave cylinder can develop external leaks or draw air into the system as its seals degrade. This reduces hydraulic pressure and makes the pedal feel soft.
Clutch systems use brake fluid, which naturally absorbs moisture over time. Under high heat, this moisture can boil and create air pockets, causing a spongy feel.
The flexible rubber clutch hose can weaken with age and bulge outward when pressurized. Instead of moving the clutch, your pedal effort goes into expanding the hose.
Weakened diaphragm springs on the pressure plate or a failing concentric release bearing can reduce mechanical resistance. This results in a soft or mushy pedal feel even if the hydraulics are perfect.