Parts for your 2013 Subaru Forester-Brake booster

2013 Subaru Forester brake booster — purpose, care, and replacement tips

Based on Subaru’s factory service information for the 2009–2013 Forester (SH) — Brake, Power Assist, “Vacuum Booster” section — plus the Subaru electronic parts catalogue (which lists a “Booster Assy – Brake” for MY13 Forester) and common repair manuals such as the Haynes Subaru Forester 2009–2018 guide, the 2013 Subaru Forester is indeed fitted with a vacuum brake booster (brake servo). So yes, this part is relevant to the model and forms part of the standard braking system on both naturally aspirated and XT variants.

On a 2013 Forester, the brake booster uses engine vacuum to multiply the force a driver puts on the pedal, so the vehicle pulls up smartly without needing a rugby player’s leg strength. Inside the round canister on the firewall lives a diaphragm and valve set, with the one-way check valve and vacuum hose, it provides consistent assist and a confident pedal feel.

Although the booster isn’t a typical “service item”, it’s smart to give it some attention during regular 10,000–15,000 km servicing. Under the bonnet, a quick look and listen goes a long way.

• Inspect the vacuum hose and clamps for cracks, softness, or oil swelling, replace any tired bits.
• Test the check valve: air should pass from hose-to-booster only, not the other way.
• With the engine running, listen for a hiss near the pedal or firewall, that can signal a diaphragm or hose leak.
• Do a function test: with the engine off, pump the pedal several times, hold pressure, then start the engine — the pedal should drop slightly as assist kicks in.

Signs it may be time to replace the booster include a noticeably hard brake pedal, longer stopping distances, hissing from the dash or engine bay, or a rough idle when braking (vacuum leak). If replacement’s on the cards, a competent DIYer can do it, but most owners will prefer a workshop. The master cylinder is usually unbolted and moved forward, the booster’s nuts are accessed under the dash. Plan on roughly 2–3 hours of labour. Fit a new grommet and check valve if they’re perished, set pedal free play to spec, and if brake lines were opened, bleed the system. After refit, repeat the function test and take a careful road test. Quality aftermarket or genuine units both work well — the key is correct installation and leak-free vacuum supply.

1. Keep the vacuum hose, grommet, and check valve in good nick.
2. Address any hissing or hard-pedal complaints promptly.
3. Verify pedal free play and booster function after any brake work.

Popular questions about 2013 Subaru Forester brake boosters

What are the signs of a failing brake booster on a 2013 Forester?
A hard brake pedal, longer stopping distances, or a hissing noise around the pedal or firewall are the big giveaways. Sometimes the engine may idle roughly when braking because of a vacuum leak. A quick booster function test (pump pedal with engine off, then start — pedal should sink slightly) helps confirm the diagnosis.

Is it safe to drive with a bad brake booster?
It’ll usually still stop, but the pedal effort skyrockets and stopping distances can blow out, especially in an emergency. That’s not worth the risk. If the pedal’s gone hard or there’s a loud hiss, get it checked and repaired before clocking more kilometres.

How often should a brake booster be replaced?
There’s no fixed interval — they typically last many years. Replace only if it fails tests or shows symptoms. During routine services, check the vacuum hose and one-way valve, replacing those small items proactively can prevent booster strain and extend its life.