Subaru Forester Intake Manifold Gasket Guide (2012-2018)
Diagnose and fix a rough idle or lean engine codes on your Forester by understanding its intake manifold gaskets.
- A rough idle and a P0171 check engine code are the most common signs of a failed intake gasket on your Forester.
- This is a vacuum leak issue; you may hear a hissing sound from the engine bay.
- Quality aftermarket brands like Beck Arnley or Victor Gaskets are reliable alternatives to more expensive OEM parts.
- While DIY is possible for experienced mechanics, it requires careful disassembly of the intake manifold.
Is Your Forester Running Rough? It Could Be the Intake Gaskets
If your 2012-2018 Forester has developed a shaky idle, hesitates when you accelerate, or has a Check Engine Light with code P0171, a leaking intake manifold gasket is a likely culprit. These gaskets create an airtight seal where the intake manifold meets the engine. When they fail, they create a vacuum leak, letting in extra air that the engine's computer doesn't measure. This leads to a 'lean' condition, where there's too much air and not enough fuel.
Common Symptoms of Failure
- Rough or Shaky Idle: The engine may vibrate or stumble when stopped at a light.
- Check Engine Light: Code P0171 (System Too Lean Bank 1) is very common with this issue.
- Hissing Noise: You may hear a distinct sucking or hissing sound from the engine bay while it's running.
- Poor Acceleration: The car might feel sluggish or hesitate when you press the gas pedal.
- Reduced Fuel Economy: An inefficient air-fuel mixture often leads to burning more gas.
Choosing the Right Aftermarket Gasket Set
When replacing the intake manifold gaskets on your Forester, you have a choice between OEM (Original Equipment Manufacturer) and aftermarket parts. For a simple sealing part like this, a quality aftermarket brand offers a reliable repair without the dealership price tag.
- OEM Gaskets: The original Subaru gaskets (Part No. 14035AA620, two required) are a guaranteed fit. They are surprisingly affordable, but you're paying for the brand name.
- Premium Aftermarket (e.g., Beck Arnley, Victor Gaskets): Brands like Victor Reinz (Victor Gaskets) and Fel-Pro are well-respected in the repair industry. Beck Arnley is known for often sourcing parts from the original OEM suppliers and repackaging them. These brands provide OEM-level quality and are an excellent choice for a durable, long-lasting repair.
Pro Tip: Since the intake manifold has to be removed for this job, it's a good time to clean your throttle body and inspect all vacuum hoses connected to the manifold for cracks or wear. Replacing them now can save you from future vacuum leaks.
Cost of Replacing Intake Manifold Gaskets (2012-2018 Forester)
| Part/Service | Estimated Cost |
|---|---|
| New OEM Gasket Set (2 gaskets) | $15 - $40 |
| New Aftermarket Gasket Set | $24 - $75 |
| Shop Labor | $240 - $450 |
| Total Professional Replacement | $265 - $525 |
Frequently Asked Questions
Are there any recalls for this problem?
No, there are no active recalls or common Technical Service Bulletins (TSBs) from Subaru for failing intake manifold gaskets on the 2012-2018 Forester. This is considered a standard wear-and-tear repair.
Can I reuse the old gaskets?
No. Intake manifold gaskets are a one-time-use part. They are designed to crush and deform to create a perfect seal. Once removed, they will not seal properly again and will cause leaks.
Is this a difficult DIY job?
For a home mechanic, this is an intermediate-level job. It requires removing the plastic intake manifold, which involves disconnecting fuel lines, various electrical connectors, and vacuum hoses. It is critical to keep debris from falling into the open engine ports during the process. If you are not comfortable with this level of disassembly, it is best left to a professional.
What causes the P0171 code?
The P0171 code means the engine is running too lean. A leaking intake manifold gasket is a primary cause, as it allows unmeasured air into the engine. The oxygen sensors detect the extra oxygen in the exhaust and trigger the code. While other issues like a dirty mass airflow sensor or a cracked air intake hose can also cause this code, a smoke test by a mechanic can confirm if the gasket is the source of the leak.
Technical Specifications
OEM Part Numbers: 14035AA620
This is a set of two gaskets required to seal the plastic intake manifold to both cylinder heads on the 2.5L FB25 engine.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Subaru Forester: