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Guide to Replacing the Catalytic Converter on a 2000-2006 Mitsubishi Eclipse

Everything you need to know before buying a new aftermarket catalytic converter for your 3G Eclipse.

4 minutes to read 2000-2006 Mitsubishi Eclipse
Difficulty
2/5
Est. Time
2.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$150-$400
⚠️ Drivable, but... — Yes, but reduced power can be a safety issue, and driving for too long can cause further engine damage.
Key Takeaways
  • Always diagnose and fix the root cause of the original converter failure before installing a new one.
  • The P0420 code is the most common indicator of a failing converter, but can also be caused by bad O2 sensors or exhaust leaks.
  • V6 models have multiple catalytic converters, which can increase replacement costs.
  • Choose a direct-fit converter for easier installation; universal converters require cutting and welding.
The catalytic converter on your 2000-2006 Mitsubishi Eclipse is a critical part of the exhaust system. Its main job is to clean up the harmful gases created by your engine before they exit the tailpipe. It uses precious metals like platinum and rhodium to convert toxic pollutants into less harmful substances like carbon dioxide and water. On the V6 Eclipse models, there are multiple converters, while the 4-cylinder has a simpler setup. A properly functioning converter is essential for passing emissions tests and keeping the check engine light off.

Is Your Eclipse's Catalytic Converter Failing?

A bad catalytic converter can cause serious headaches, from failing your emissions test to making your car run poorly. The most common sign of a problem is the check engine light, often with a P0420 code, which means the converter's efficiency is below the required threshold. You might also notice a significant drop in engine power, a rotten egg or sulfur smell from the exhaust, or a rattling sound from under the car. The rattling is often caused by the internal ceramic honeycomb breaking apart.

🎬 See how to diagnose and fix common exhaust rattles.

Don't Ignore the Root Cause

Catalytic converters usually don't fail on their own. They are often damaged by another problem with the engine. Common causes include a misfiring engine, leaking fuel injectors, bad oxygen sensors, or burning oil/coolant. If you don't fix the original problem, your new converter will likely fail quickly, too.

Choosing the Right Aftermarket Converter

When shopping for a new catalytic converter, you'll find a wide range of prices and brands. For the 3G Eclipse, you have options from basic replacements to high-performance units. It's important to understand the differences before you buy.

Brand Tiers for Your Eclipse

  • Performance (MagnaFlow): MagnaFlow is a well-regarded brand that offers both direct-fit and universal converters for the Eclipse. They are known for high-quality stainless steel construction which resists corrosion and often feature designs that can improve exhaust flow. While more expensive, they are a popular choice for owners looking for longevity and a potential performance boost.
  • Standard Replacement (Walker, Eastern Catalytic): Brands like Walker and Eastern Catalytic are popular choices for a balance of quality and price. Walker is known for having a huge catalog and good fitment, even if their parts aren't as nicely finished as premium brands. Eastern Catalytic also offers a 50,000-mile warranty on catalyst performance on some models, which is better than the federally mandated 25,000 miles.
  • Economy (AP Exhaust, Davico, Evan Fischer): These brands offer a budget-friendly solution to get your car back on the road. However, be aware that fitment can sometimes be an issue with lower-cost parts, potentially requiring modification. While brands like Davico can be a good value, some users report issues with check engine lights returning or needing to do extra work during installation.

Direct-Fit vs. Universal Converters

Direct-fit converters are designed to bolt right into your Eclipse's exhaust system without any cutting or welding, making installation much easier. 🎬 Watch this DIY tutorial on how to replace your converter. Universal converters are cheaper but require cutting the old converter out and welding the new one in, which adds to labor costs if you're not doing it yourself.

Cost of Replacing Your Eclipse's Catalytic Converter

The price can vary a lot depending on the brand you choose and labor costs in your area.

Part/Service Estimated Cost
New Aftermarket Catalytic Converter $73.94 - $674.06
New OEM (Dealer) Catalytic Converter $800 - $2300+
Shop Labor for Installation $150 - $400

Frequently Asked Questions (FAQ)

What is a P0420 code and what does it mean for my Eclipse?

A P0420 code stands for "Catalyst System Efficiency Below Threshold (Bank 1)". Your car's computer uses two oxygen sensors to measure the converter's performance. If the readings from the sensor after the converter start to look like the readings from the sensor before it, the computer knows the converter isn't cleaning the exhaust properly and triggers the check engine light. While this often means the converter is bad, it can also be caused by exhaust leaks or faulty oxygen sensors.

Do I need a CARB-compliant converter?

It depends on where your vehicle is registered. States like California, Colorado, New York, and Maine have stricter emissions laws and require converters that are certified by the California Air Resources Board (CARB). These converters are more expensive because they contain more precious metals to meet the higher standards. Always check your local laws before buying, as installing a non-compliant part is illegal in these states.

Were there any recalls for the 2000-2006 Eclipse catalytic converter?

No recalls were found specifically for the catalytic converter on the 2000-2005 models. However, Mitsubishi did issue a Technical Service Bulletin (TSB-13-15-001) that extended the warranty on the catalytic converters for some 2006 V6 Eclipse models due to potential catalyst layer separation causing P0421 or P0431 codes. This was not a safety recall. Always check with a dealer for any outstanding campaigns for your specific vehicle.

Can I clean my catalytic converter instead of replacing it?

While there are fuel additives that claim to clean catalytic converters, they are generally not a permanent fix, especially if the converter is physically damaged or melted inside. These products might temporarily turn off a check engine light if the converter is only slightly clogged, but they cannot repair a broken internal structure. 🎬 Watch a real-world test of catalytic converter treatments on an Eclipse. If your converter has failed, replacement is almost always the only real solution.

How to Fix the P0420 Code Yourself and Save Money
How to Fix the P0420 Code Yourself and Save Money
P0420 CODE CAUSES AND SOLUTIONS
P0420 CODE CAUSES AND SOLUTIONS
Getting Rid Of Code P0420 With A Little Spring Cleaning
Getting Rid Of Code P0420 With A Little Spring Cleaning
Check Engine Light Code P0420 on Your Car / Truck? Replace These Parts to Pass Emissions
Check Engine Light Code P0420 on Your Car / Truck? Replace These Parts to Pass Emissions
Catalytic Converter Replacement – DIY Tutorial
Catalytic Converter Replacement – DIY Tutorial
How to Replace Catalytic Converter in Your Car
How to Replace Catalytic Converter in Your Car
Is your Exhaust Rattling This is how to fix it cheap!
Is your Exhaust Rattling This is how to fix it cheap!
Exhaust Rattling?  Easy Fix for $5
Exhaust Rattling? Easy Fix for $5
How To Fix Exhaust Rattles - EricTheCarGuy
How To Fix Exhaust Rattles - EricTheCarGuy
Dose it Work? 3G Mitsubishi Eclipse Catalytic converter Treatment
Dose it Work? 3G Mitsubishi Eclipse Catalytic converter Treatment

Technical Specifications

OEM Part Numbers: 1555A085 MN153174

The 2000-2006 Mitsubishi Eclipse was available with a 2.4L 4-cylinder (4G64) or a 3.0L V6 (6G72) engine. The V6 models feature a more complex exhaust system with multiple catalytic converters integrated into the exhaust manifolds as well as an underbody converter. The 4-cylinder model has a single manifold converter and sometimes a secondary converter. Most aftermarket replacements are bolt-on, direct-fit units, but universal weld-in options are also available.

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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.

Year Coverage
This article covers the Catalytic Converter for:
  • Mitsubishi Eclipse: 2000200120022003200420052006
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