A Guide to Replacing the Catalytic Converter on a 2000-2004 Mitsubishi Galant
Everything you need to know before buying a new aftermarket catalytic converter for your Galant.
- For 2.4L engines, always check for cracks in the exhaust manifold before replacing the converter, as this can cause a false P0421 code.
- Always diagnose and fix the root cause of the original failure (e.g., misfires, leaks) to prevent damaging the new converter.
- V6 models have multiple converters; be sure to diagnose which one has failed before ordering parts.
- To avoid a recurring check engine light, choose a quality aftermarket brand like MagnaFlow or Walker over budget options.
Is Your Galant's Catalytic Converter Failing?
When a catalytic converter goes bad, your car will give you clear warning signs. The most common sign is the check engine light turning on. For the 2000-2004 Galant, this often means a specific trouble code has been stored in the car's computer.
- Check Engine Light: This is usually the first thing you'll notice. The code is often P0420 (Catalyst System Efficiency Below Threshold Bank 1). 🎬 Watch: A mechanic explains what the P0420 code really means. Some Mitsubishis are also known for showing a P0421 code, which means "Warm Up Catalyst Efficiency Below Threshold." If you have a V6 model, you might see a P0430 code for the second cylinder bank.
- Poor Engine Performance: A clogged converter can block exhaust flow, which chokes the engine. You might feel like the car is slow to accelerate or has no power, especially when trying to go up hills.
- Bad Smell: A failing converter can't properly process all the chemicals in the exhaust, which can lead to a rotten egg or sulfur smell from the tailpipe.
- Rattling Noise: If the ceramic honeycomb inside the converter breaks apart, you may hear a rattling sound from under the car as the loose pieces move around.
Special Note for 2.4L Engine Owners
On the 4-cylinder Galant, the front catalytic converter is part of the exhaust manifold. A very common issue is for the manifold itself to develop a small crack. This crack lets oxygen into the exhaust, which fools the oxygen sensors and triggers a P0421 code, making you think the converter has failed when it might still be good. Always have a mechanic inspect the manifold for cracks before you buy a new converter. Welding the crack can sometimes fix the problem for much less money.
🎬 See this step-by-step guide to replacing the 2.4L exhaust manifold.Choosing the Right Aftermarket Converter
When replacing the converter on your Galant, you don't have to buy an expensive OEM part from the dealer. Aftermarket parts can work well, but quality matters. Cheaper converters often have less of the precious metals needed to clean the exhaust, which can cause the check engine light to come back on. Here’s a breakdown of available brands.
Brand Quality Tiers
- Premium Aftermarket (MagnaFlow): Brands like MagnaFlow are known for high-quality construction, often using stainless steel for better durability. They focus on meeting or exceeding emission standards to keep the check engine light off and are a good choice if you plan to keep your Galant for a long time.
- Standard Aftermarket (Walker Exhaust): Walker is a trusted name that provides a good balance of quality and price. They are known for making parts that fit correctly and work reliably for daily driving, making them a popular and sensible choice.
- Economy Aftermarket (AP Exhaust, Eastern, Davico): These brands are the most budget-friendly. However, reviews are mixed. Some owners report premature failures or fitment issues that require extra work during installation. These are best if you're on a tight budget, but be aware they may not last as long as premium options.
Federal vs. California Emissions
You must buy a converter that is legal in your state. Some states, like California, New York, and Maine, follow California Air Resources Board (CARB) rules and require specific CARB-compliant converters. Most other states use the federal EPA standard. Always check which type your state requires before buying.
How Much Does a Replacement Cost?
The cost depends on your engine (2.4L 4-cylinder or 3.0L V6) and the parts you choose. V6 models have more than one converter, which can increase the total cost if multiple need replacement.
| Part or Service | Estimated Cost |
|---|---|
| New Aftermarket Converter | $74 - $674 |
| New OEM Converter | $1,000 - $2,500+ |
| Shop Labor | $150 - $350 |
| Total Aftermarket Replacement | $224 - $1,024 |
| Total OEM Replacement | $1,150 - $2,850+ |
Cost estimates are approximate and can vary by location and specific vehicle configuration.
Frequently Asked Questions
Do I have to replace my oxygen sensors with the catalytic converter?
It is highly recommended. The same issue that damaged your converter (like a rich fuel mixture) can also damage the oxygen sensors. A faulty oxygen sensor can also provide bad information to the car's computer, which might make it seem like your new converter isn't working. Replacing them at the same time is a smart investment.
Was there a recall on the 2000-2004 Galant catalytic converter?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no safety recalls for the catalytic converters on these vehicles. Mitsubishi did issue a Technical Service Bulletin (TSB) that extended the warranty for some manifold converters due to a known defect, but this warranty has long since expired for these model years.
How many catalytic converters does my Galant have?
It depends on your engine. The 2.4L 4-cylinder models typically have two: one integrated with the exhaust manifold at the front and a second one under the car. The 3.0L V6 models have at least two, one for each cylinder bank, and may have a third one further down the exhaust system.
Can I install a catalytic converter myself?
If you have good mechanical skills and tools, yes. Direct-fit converters are designed to bolt into place without special work. However, rusted bolts can make the job very difficult. Universal-fit converters are cheaper but require cutting your old exhaust pipe and welding the new one in, which should be done by a professional.
🎬 Watch: This DIY tutorial shows how to replace a converter yourself.What could cause my new converter to fail?
A catalytic converter usually fails because of another problem with the engine. Common causes include engine misfires (from bad spark plugs or coils), leaking fuel injectors, or burning oil or coolant. If you don't fix the root cause, your new converter will likely fail quickly.
Helpful Videos
Technical Specifications
Configuration varies by engine. The 2.4L 4-cylinder uses an exhaust manifold with an integrated catalytic converter and a secondary downstream converter. The 3.0L V6 uses separate converters for each cylinder bank (Bank 1 and Bank 2) and may have a third downstream converter.
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.
- Mitsubishi Galant: