A Subaru Legacy Owner's Guide to the 2011-2017 Catalytic Converter
Facing a P0420 code or emissions test failure? This guide covers everything you need to know before replacing your catalytic converter.
- The P0420 code is common but doesn't always mean the converter is bad; check for exhaust leaks and faulty O2 sensors first.
- Some 2015-2016 models were part of a recall for cracking exhaust pipes that include the converter; check your VIN with a dealer.
- Fix any engine misfires, oil burning, or coolant leaks *before* replacing the converter to prevent damaging the new part.
- Higher-quality aftermarket brands like MagnaFlow or Walker are more likely to solve the P0420 code than budget options.
Is Your Legacy's Catalytic Converter Failing?
A failing catalytic converter on your 2011-2017 Subaru Legacy can cause several noticeable problems. Because this part is so important for engine performance and emissions, symptoms usually don't go unnoticed for long.
The Notorious P0420 Check Engine Light
The most common sign of a problem is the check engine light illuminating with a P0420 "Catalyst System Efficiency Below Threshold" code. While this code often points directly to a failing converter, it's not a guaranteed diagnosis for Subarus. Faulty oxygen sensors, exhaust leaks, or an engine running too rich can also trigger this code. Always investigate these other potential causes 🎬 Watch: Troubleshooting the P0420 code and finding the right solution. before committing to a costly converter replacement.
Known Issues: Recalls and Service Bulletins
Subaru issued a voluntary emissions recall (WUJ-95) for some 2015-2016 Legacy models. The front exhaust pipe, which contains the catalytic converter, was prone to developing cracks at the flexible bellows, leading to exhaust leaks, noise, and potential emissions test failure. Another service campaign (WRE-21) involved replacing ignition coils and, if a specific trouble code was present, replacing the front exhaust pipe and converter at no cost. While these campaigns may have expired, it's worth checking with a Subaru dealer to see if your vehicle's VIN was affected.
Choosing the Right Aftermarket Catalytic Converter
When your original converter fails, you have a choice between an expensive OEM (Original Equipment Manufacturer) part from Subaru and a more affordable aftermarket one. OEM converters are known for their high-quality materials and longevity but come at a premium price. Aftermarket converters offer significant savings, but quality can vary widely between brands.
Aftermarket Brand Tiers for Your Subaru
Not all aftermarket parts are created equal. For a sensitive system like your Subaru's, choosing the right brand can be the difference between a lasting repair and the check engine light returning in a few months.
- Premium Aftermarket (MagnaFlow, Walker): Brands like MagnaFlow and Walker are often recommended by Subaru owners as reliable alternatives to OEM. They tend to use better materials and construction, offering a good balance of price and performance. Many users report success in clearing the P0420 code and passing emissions tests with these brands.
- Standard/Economy Aftermarket (AP Exhaust, Davico, Eastern Catalytic): These brands provide a budget-friendly solution. However, owner experiences are mixed. Some report that cheaper converters may not have enough precious metals to satisfy the Subaru's sensitive ECU, causing the P0420 code to return. Fitment can also be an issue, sometimes requiring adjustments during installation. 🎬 See this walkthrough for replacing a Subaru catalytic converter. While they can be a viable option for an older vehicle, be aware of the potential for a shorter lifespan or persistent check engine light issues.
A Note on CARB Compliance: If you live in California, Colorado, New York, Maine, or another state that has adopted California Air Resources Board (CARB) emissions standards, you MUST install a CARB-compliant catalytic converter. Federal (EPA) converters are not legal for sale or use in these states and will cause your vehicle to fail inspection.
Cost of Replacing a Subaru Legacy Catalytic Converter
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Converter | $140 - $625 |
| New OEM Converter | $1,000 - $2,200+ |
| Shop Labor | $150 - $300 |
*Prices are estimates and can vary based on your location, vehicle specifics, and the repair shop.
Frequently Asked Questions
Why did my catalytic converter fail?
Converters can fail from age, but failure is often caused by another problem. An engine that burns oil or coolant can contaminate the converter. A misfiring engine can send unburned fuel into the exhaust, overheating and melting the converter's internal structure. It's crucial to fix any underlying engine issues before installing a new converter, or the new part will likely fail as well.
Can I just clean my catalytic converter?
While some fuel additives claim to clean converters, they are not a reliable fix for a physically damaged or internally melted unit. If the converter is merely clogged with carbon, a professional cleaning might help, but it's rarely a long-term solution for a P0420 code. If the internal honeycomb structure is broken or melted, replacement is the only option.
Will an aftermarket converter turn off my check engine light?
It depends on the brand. Higher-quality aftermarket converters from brands like MagnaFlow or Walker are designed with a sufficient load of precious metals to meet OE performance and are more likely to keep the P0420 code from returning. Cheaper, economy-grade converters sometimes lack the efficiency needed for the sensitive Subaru monitoring system, and the light may come back on.
Should I replace my oxygen sensors at the same time?
It is highly recommended. Old or slow-reacting oxygen sensors can provide incorrect data to the car's computer, sometimes causing a P0420 code on their own. Installing new sensors with a new converter ensures the entire system is working with accurate information, and it's a required step for the warranty on many new converters.
🎬 Watch: How to replace the oxygen sensors on your Legacy.Helpful Videos
Technical Specifications
For the 2011-2017 Subaru Legacy, the catalytic converter is often integrated into the front exhaust pipe assembly. The 2.5L 4-cylinder and 3.6L 6-cylinder engines use different exhaust configurations. Ensure the replacement part is a direct-fit for your specific engine and check for CARB compliance if required by your state.
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 Legacy:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your Legacy's Catalytic Converter Failing?
- The Notorious P0420 Check Engine Light
- Known Issues: Recalls and Service Bulletins
- Choosing the Right Aftermarket Catalytic Converter
- Aftermarket Brand Tiers for Your Subaru
- Cost of Replacing a Subaru Legacy Catalytic Converter
- Frequently Asked Questions
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