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2021 Ascent: Soft/Spongy Brake Pedal and Reduced Braking Power

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Ryan M. · rep 0 · May 22, 3:15 AM · 1 replies · solved · Question

Vehicle: 2021 Subaru Ascent Touring

Hi everyone,

I'm experiencing a worrying issue with my 2021 Subaru Ascent Touring, which has about 38,000 miles on it. Over the last week or so, the brake pedal has started to feel really soft and spongy. I have to press it much further down than before to get the car to slow down, and the overall braking power feels significantly reduced.

There are no warning lights on the dash, and I haven't noticed any leaks under the car. I checked the brake fluid reservoir, and it seems to be at a normal level. This is making me nervous, especially with my family in the car. What could be causing this soft brake pedal, and what should I do next?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:15 AM

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ClearTheCode admin answer:

A soft or spongy brake pedal and reduced braking power on your 2021 Subaru Ascent are serious safety concerns that require immediate attention. While no warning lights are on, this doesn't mean there isn't a critical issue with your hydraulic braking system.

Common Causes:

  1. Air in the Brake Lines: This is the most common cause of a spongy pedal. Air is compressible, unlike brake fluid, so when you press the pedal, the air compresses before the fluid transmits pressure to the calipers. This can happen after brake service if the system wasn't bled properly, or if a small leak allowed air in.
  2. Brake Fluid Leak: Even if you don't see a puddle, a small, slow leak in a brake line, caliper, or wheel cylinder could be allowing fluid to escape and air to enter. Check for damp spots around the calipers, master cylinder, and along the brake lines.
  3. Failing Master Cylinder: The master cylinder is responsible for generating hydraulic pressure. If its internal seals are worn, fluid can bypass them, leading to a soft pedal that might slowly sink to the floor when held down. This is a serious issue.
  4. Worn Brake Pads/Rotors (less likely for spongy pedal): While worn pads/rotors cause reduced braking, they typically result in a firm pedal that just doesn't stop the car effectively, rather than a spongy feel.
  5. Contaminated Brake Fluid: Old or contaminated brake fluid can boil under extreme conditions, creating vapor (air) in the lines.

Troubleshooting Steps:

  1. Pump the Brakes: With the engine off, pump the brake pedal several times. If the pedal firms up, it might indicate air in the lines or a master cylinder issue.
  2. Check for Leaks: Thoroughly inspect all brake lines, calipers, and the master cylinder for any signs of fluid leakage, even small drips.

When to See a Shop:

Do not delay in getting your Subaru Ascent inspected by a professional mechanic. Driving with compromised brakes is extremely dangerous. A qualified technician will:

  • Perform a Thorough Brake System Inspection: This includes checking all brake lines, hoses, calipers, and the master cylinder for leaks or damage.
  • Bleed the Brake System: If air is found, they will properly bleed the entire system to remove it.
  • Test the Master Cylinder: If bleeding doesn't resolve the issue, they will test the master cylinder for internal failure.
  • Inspect Brake Fluid Quality: Check the condition and moisture content of your brake fluid.

Prompt diagnosis and repair are essential to restore your braking system to full functionality and ensure your safety.

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