This post contains affiliate links. This means I will make a commission at no extra cost to you should you click through and make a purchase [ “As an Amazon Associate, I earn from qualifying purchases.” ]. Read the full disclosure here.
Seafoam Catalytic Converter Cleaner: Does It Work and How to Use It? GuideMechanic.Com The catalytic converter is a critical component in your vehicle’s emissions system.
Over time, it can become clogged with carbon deposits, unburned fuel, and other residue, which can lead to performance issues, increased emissions, and even a Check Engine Light (CEL), especially error codes like P0420 or P0430.
One of the most popular solutions car enthusiasts turn to is Seafoam. While Seafoam doesn’t have a dedicated product labeled strictly as “Catalytic Converter Cleaner,” several of its products—especially Seafoam Motor Treatment and Seafoam Spray—are used by mechanics and DIYers alike to clean the engine and emissions system, including the catalytic converter.
In this article, we’ll explore what Seafoam is, how it works, how it impacts the catalytic converter, and whether it’s an effective method for improving emissions system health.
See Also: Rislone Catalytic Converter Cleaner: What It Is, How It Works
Seafoam Catalytic Converter Cleaner: Does It Work and How to Use It?
What is Seafoam?
Seafoam is a well-known American brand that manufactures a range of engine cleaning products. Its most famous formula, Seafoam Motor Treatment, is a petroleum-based liquid that can be added to:
- The fuel tank
- The crankcase (oil system)
- The intake system
Seafoam helps to clean carbon deposits, sludge, and varnish that accumulate in an engine over time. Its versatility and effectiveness have earned it a loyal following among mechanics and DIY car owners for over 75 years.
Can Seafoam Clean the Catalytic Converter?
Seafoam does not manufacture a product specifically labeled as “catalytic converter cleaner.” However, it can indirectly clean the catalytic converter by:
- Improving fuel combustion
- Reducing carbon buildup in the combustion chamber
- Preventing unburned fuel from entering the exhaust system
- Cleaning intake valves and pistons, which reduces emissions
By restoring proper combustion and reducing carbon buildup, Seafoam helps reduce the contaminants that cause the catalytic converter to clog in the first place. This process may help clear minor blockages or improve converter performance—especially when used regularly.
Which Seafoam Products Are Used for Catalytic Converter Cleaning?
Here are the main Seafoam products commonly used to support catalytic converter health:
1. Seafoam Motor Treatment
- Use: Add to gas tank, oil crankcase, or intake manifold
- Purpose: Cleans fuel injectors, intake valves, and combustion chambers
- Effect on Converter: Reduces unburned fuel and carbon that would otherwise clog the catalytic converter
2. Seafoam Spray
- Use: Sprayed directly into the throttle body
- Purpose: Cleans intake valves and combustion chamber directly
- Effect on Converter: Cleans areas upstream of the converter, helping reduce contaminants reaching it
3. Seafoam High Mileage Treatment
Designed for engines with over 75,000 miles, this version has additives specifically to combat carbon buildup in older engines.
Which Seafoam Products Are Used for Catalytic Converter Cleaning
Symptoms of a Dirty or Failing Catalytic Converter
Before using any cleaner, it’s essential to know the signs of a failing or clogged catalytic converter:
- Check Engine Light (often with code P0420 or P0430)
- Reduced engine performance
- Increased fuel consumption
- Sulfur/rotten egg smell from the exhaust
- Failed emissions test
- Poor acceleration or rough idle
If you notice any of these issues, trying a cleaning solution like Seafoam could be a worthwhile first step—especially before considering a costly converter replacement.
How to Use Seafoam to Help Clean Your Catalytic Converter
Here’s a step-by-step guide on how to use Seafoam Motor Treatment and Seafoam Spray in ways that may help clean your emissions system, including the catalytic converter.
Method 1: Seafoam in the Fuel Tank
Purpose:
- Cleans fuel system, combustion chamber, and reduces unburned fuel that reaches the converter.
Instructions:
- Wait until your tank is low (around 1/4 to 1/2 full).
- Add 1 ounce of Seafoam per gallon of fuel (up to 16 oz total).
- Drive normally—highway driving is best to get the exhaust system hot.
- Repeat every 3,000–5,000 miles as maintenance.
Result:
- This can help reduce carbon buildup and improve combustion, decreasing the load on the catalytic converter.
Method 2: Seafoam Spray in the Intake
Purpose:
- Directly cleans intake valves and pistons.
Instructions:
- Warm up your engine to normal operating temperature.
- Remove the air intake hose to access the throttle body.
- Spray Seafoam slowly into the throttle body while maintaining engine RPM at 1,500.
- Once the can is empty, turn off the engine and let it “hot soak” for 10–15 minutes.
- Restart the engine and drive for 10–20 miles at highway speeds.
Result:
- By cleaning upstream components, less carbon reaches the catalytic converter, improving its efficiency.
Which Seafoam Products Are Used for Catalytic Converter Cleaning
What Kind of Results Can You Expect?
Many users report noticeable improvements after using Seafoam products:
✅ Benefits:
Improved acceleration
Smoother idle
Lower emissions
Check Engine Light disappears (in some cases)
Better fuel economy
⚠️ Limitations:
Seafoam won’t fix melted, cracked, or severely damaged catalytic converters.
It’s most effective on minor clogs and as a preventive measure.
Results may vary depending on the severity of the buildup.
Real User Reviews
“I used Seafoam in my tank and spray in the throttle body. After a week, the P0420 code was gone and my car ran noticeably better.”
“My car failed emissions, and I didn’t want to spend $1,000 on a new cat. Tried Seafoam and passed on the retest!”
“Didn’t fix the converter completely, but definitely helped reduce the smell and improve engine power.”
How Often Should You Use Seafoam?
- Add to the fuel tank every 3,000–5,000 miles
- Use Seafoam Spray every oil change or when doing a tune-up
- Great for seasonal maintenance or long road trips
Where to Buy Seafoam Products
Seafoam is widely available both in-store and online:
- Amazon
- Walmart
- AutoZone
- O’Reilly Auto Parts
- Canadian Tire
- Advance Auto Parts
Prices typically range from $8 to $15 per bottle or can, making it an affordable maintenance option.
Is Seafoam Safe?
Yes—Seafoam is made from 100% petroleum-based ingredients and is safe for:
- Gasoline and diesel engines
- 2-stroke and 4-stroke motors
- Turbocharged and naturally aspirated engines
- Oxygen sensors and catalytic converters (when used correctly)
It’s also EPA-registered and does not contain harsh chemicals that could damage your engine.
Final Verdict: Is Seafoam a Catalytic Converter Cleaner?
✅ Yes—but indirectly.
Seafoam isn’t labeled as a “Catalytic Converter Cleaner,” but it helps restore converter function by:
- Cleaning upstream engine components
- Reducing carbon deposits
- Promoting complete fuel combustion
For best results, use it early—before severe damage occurs. If your catalytic converter is only mildly clogged or inefficient due to carbon buildup, Seafoam can be a cheap and easy first step that might save you hundreds or even thousands of dollars in repairs.
Quick Recap
- Product: Seafoam Motor Treatment / Seafoam Spray
- Effect: Helps reduce buildup and emissions that clog catalytic converters
- Use: Fuel system, intake system, crankcase
- Best For: Routine maintenance, early signs of converter inefficiency
- Safe For: Oxygen sensors, catalytic converters, fuel systems
- Price: ~$10 per bottle
- Where to Buy: Amazon, Walmart, AutoZone, etc.
- Seafoam Catalytic Converter Cleaner: It Work & How to Use It? - April 18, 2025
- Rislone Catalytic Converter Cleaner: What It Is, How It Works - April 18, 2025
- Wynn’s Catalytic Converter Cleaner 325ml - April 17, 2025