DIY

What Causes Spongy and Soft Brakes? Plus How to Fix Them

Reading Time: 4 minutes

Do your car’s brakes feel spongy or soft when you apply the pedal? That unnerving sensation can greatly compromise the overall safety of your vehicle. In fact, a soft or spongy brake pedal is so dangerous, that you’ll want to forgo driving your car altogether until the problem is fixed.

It’s helpful to know what might be causing the concern, regardless of whether you plan to tackle the issue yourself or let a professional do the job for you.  

stepping on the car brake pedal
A soft or spongy brake pedal is so dangerous that you’ll want to forgo driving your car altogether until the problem is fixed.

What’s the Difference Between Spongy Brakes and Soft Brakes?

A spongy brake pedal has a slightly different feel than a soft brake pedal. Spongy brakes give the sensation that you’re pushing against a spring when pressing down on the brake pedal. On the other hand, a soft brake pedal either goes to the floor or goes down too easily.

What Causes a Spongy Brake Pedal or a Soft Brake Pedal?

If you’re dealing with a spongy brake pedal, that usually means air is trapped in the brake system. Of course, air trapped in the system isn’t the only possibility. All of the following problems are common causes of a spongy brake pedal:

  • Air in the brake system
  • Contaminated brake fluid
  • A brake hose that’s bulging under pressure
  • Worn brake pads/shoes or rotors/drums
  • Sticking brake caliper

A soft brake pedal usually indicates a loss of hydraulic pressure. All of the following problems are common causes of a soft brake pedal:

  • Air in the brake system
  • Contaminated brake fluid
  • A brake fluid leak
  • An extremely low brake fluid level
  • A faulty master cylinder

Although it’s not as common, a faulty antilock brake system (ABS) hydraulic control unit can also cause a soft brake pedal.

It’s worth noting that sometimes it’s hard to distinguish a spongy brake pedal from a soft brake pedal. Because of this, the lists above are not always mutually exclusive.

How to Fix Spongy Brakes or Soft Brakes

Obviously, you don’t want to mess with your car’s brakes unless you know what you’re doing. If you’re uncertain of your abilities, it’s best to let a professional diagnose and repair your car’s brake problems.

mechanic repairing brake disc
The first thing you’ll want to consider to diagnose and repair spongy or soft brakes is whether the brake system was serviced recently.

But if you’re a skilled DIYer, you might be able to diagnose and repair spongy or soft brakes yourself.

The first thing you’ll want to consider is whether the brake system was serviced recently. Anytime the hydraulic brake system is opened for repair, air gets inside. That air must be bled from the system before the brakes will work properly.

So, if you just finished working on your car’s hydraulic system and the brakes now feel spongy or soft, you’ll want to make sure the brakes are bled properly before trying anything else.

If you still have spongy brakes after bleeding, consult a repair manual or repair database to ensure you’re using the correct bleeding procedure. Nowadays, bleeding procedures can vary quite a bit between vehicles. In some cases, you may even need a scan tool to do the job properly.

Mechanic checks level of brake fluid in container
A low brake fluid level indicates there’s a leak somewhere that you’ll need to pinpoint and repair.

But wait—what if the brake system hasn’t been serviced recently? Then, you’ll need to perform a thorough diagnosis of the braking system to determine what’s wrong. 

Start by checking the brake fluid level and condition. A low brake fluid level indicates there’s a leak somewhere that you’ll need to pinpoint and repair. Also, if you find the brake fluid is contaminated in some way, you’ll need to flush and bleed the system.

Next, check the condition of the brake pads and the brake shoes (if equipped). Although somewhat rare, extremely worn pads or shoes can cause a spongy brake pedal. Be sure to check the calipers and the wheel cylinders (if equipped) while you’re at it. Replace any faulty components as needed and recheck the brake system.

If everything checks out okay up to this point, you’ll need to dive into some deeper diagnostics. For example, you may need to isolate the master cylinder from the brake system to pinpoint the problem. It’s a good idea to consult a repair manual or repair database for the appropriate diagnostic procedure.

Is It Safe To Drive With a Spongy or Soft Brake Pedal?

The most important thing to remember is that you should never drive a car with a spongy or soft brake pedal. Your car’s braking ability will either be severely compromised—or the brakes may stop working altogether. Do not drive the vehicle until the problem is fixed.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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