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Spongy Brake Pedal on 2020 Ascent - What's Causing It?

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Mike T. · rep 0 · May 25, 2:15 AM · 1 replies · solved · Question

Vehicle: 2020 Subaru Ascent Touring

Hello Ascent owners,

I've noticed that the brake pedal in my 2020 Subaru Ascent Touring has started to feel spongy or soft over the past few weeks. I have to press it down further than before to get the same braking power, and it just doesn't feel as firm as it used to.

There are no visible leaks under the car, and the brake fluid reservoir seems to be at the correct level. The car has about 45,000 miles on it. Has anyone experienced this with their Ascent? What could be the potential causes for a soft brake pedal?

Thanks for your help!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:15 AM

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ClearTheCode admin answer:

A spongy or soft brake pedal on your 2020 Subaru Ascent is a significant safety concern that requires immediate attention. Even without visible leaks, there are several internal issues that can cause this symptom.

Here are the most common causes for a soft brake pedal:

  1. Air in the Brake Lines: This is the most frequent cause. Air is compressible, unlike brake fluid, so it creates a spongy feel. Air can enter the system after a component replacement, if the fluid reservoir runs too low, or if a small leak allows air in without noticeable fluid loss.
    • Action: The brake system needs to be properly bled to remove all air. This might require a pressure bleeder or a scan tool for ABS systems.
  2. Failing Master Cylinder: The master cylinder is responsible for generating hydraulic pressure. If its internal seals are worn, fluid can bypass the piston, leading to a loss of pressure and a soft pedal that might slowly sink to the floor when held.
    • Action: A professional diagnosis is needed to confirm master cylinder failure. If confirmed, replacement is required.
  3. Contaminated Brake Fluid: Over time, brake fluid can absorb moisture, lowering its boiling point. If the fluid boils during heavy braking, vapor pockets form, leading to a spongy pedal. Also, incompatible fluids can cause seal degradation.
    • Action: Brake fluid should be flushed and replaced according to Subaru's maintenance schedule (typically every 30,000 miles or 2 years).
  4. Worn Brake Calipers or Wheel Cylinders: While less common for a spongy feel without other symptoms, worn caliper piston seals or a sticking piston can sometimes contribute to inconsistent pedal feel.
    • Action: Inspect calipers for leaks or sticking. Ensure pistons move freely.
  5. Vacuum Booster Issues: The brake booster assists in applying braking force. A failing booster usually results in a hard pedal, but sometimes a vacuum leak can cause inconsistent pedal feel.
    • Action: Check vacuum lines to the booster for leaks. Professional diagnosis if a booster issue is suspected.

When to See a Shop:

Do not delay having your Ascent inspected. A spongy brake pedal directly impacts your ability to stop the vehicle safely. It's imperative to take your Ascent to a qualified mechanic immediately. They will perform a thorough inspection, which typically includes:

  • Checking brake fluid condition and level.
  • Inspecting all brake lines, calipers, and wheel cylinders for leaks.
  • Testing the master cylinder for internal leaks.
  • Bleeding the brake system to remove any air.
  • Checking the brake booster operation.

Prompt diagnosis and repair are crucial for your safety and the safety of others on the road.

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