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My 2017 Q50 Red Sport has a really soft brake pedal, what's going on?

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Mike T. · rep 0 · May 25, 3:48 AM · 1 replies · solved · Question

Vehicle: 2017 Infiniti Q50 Red Sport

Hey everyone, I've got a 2017 Infiniti Q50 Red Sport with about 70k miles on it. Lately, the brake pedal feels really soft and spongy, almost like I have to push it all the way to the floor to get good stopping power. It's making me a bit nervous driving, especially in traffic.

I haven't noticed any leaks under the car, and the brake fluid reservoir looks to be at the correct level. The car still stops, but it just doesn't feel right. Is this a common issue with these Q50s?

I'm wondering if it could be air in the lines, or something more serious like the master cylinder. Any advice on what I should check first before taking it to a shop? Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:48 AM

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ClearTheCode admin answer:

A soft or spongy brake pedal in your 2017 Infiniti Q50 Red Sport can be concerning and points to several potential issues within the hydraulic braking system. It's crucial to address this promptly for safety.

Common Causes:

  1. Air in the Brake Lines: This is one of the most frequent culprits. Air can enter the system during brake pad/rotor replacement, fluid flush, or if fluid levels drop too low. Air compresses, unlike fluid, leading to a spongy pedal feel.
  2. Low Brake Fluid: Although you checked the reservoir, a slight drop could indicate a leak elsewhere in the system (caliper, brake line, master cylinder).
  3. Worn or Failing Master Cylinder: The master cylinder is responsible for pressurizing the brake fluid. If its internal seals are worn, fluid can bypass them, leading to a loss of pressure and a soft pedal.
  4. Brake Fluid Contamination or Degradation: Old or contaminated brake fluid can lose its effectiveness, affecting pedal feel.
  5. Faulty Brake Caliper: A sticking or leaking caliper can also contribute to a soft pedal, though typically this would also cause uneven braking or pulling.

When to See a Shop:

  • Immediately: If the pedal goes to the floor with minimal resistance, or if braking performance is significantly reduced. Do not drive the vehicle.
  • As soon as possible: If you suspect a fluid leak, or if bleeding the brakes yourself doesn't resolve the issue. A professional can perform a thorough inspection, identify leaks, test the master cylinder, and ensure proper bleeding.

Steps to Consider (DIY or Professional):

  1. Inspect for Leaks: Carefully check all brake lines, calipers, and the master cylinder for any signs of fluid leaks. Look for wet spots or drips.
  2. Check Brake Fluid Quality: If the fluid looks dark or murky, it might be time for a brake fluid flush and replacement.
  3. Bleed the Brake System: This process removes air from the lines. It's often a two-person job or requires specialized tools. Start with the wheel furthest from the master cylinder and work your way closer.
  4. Master Cylinder Test: A mechanic can perform a simple test to determine if the master cylinder is holding pressure correctly. If it's failing, replacement is necessary.

Given the safety implications, if you're not comfortable diagnosing or performing these repairs, it's always best to consult with a certified Infiniti technician.

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