Next Level Performance
September 7, 2026 • 10 min read
Our Verdict
For a 2006–2009 S2000, the MagnaFlow 5461261 California-grade direct-fit converter is the cleanest, CARB-legal way to clear a P0420 code and keep the check-engine light off.
Driving a 2000–2005 car? The MagnaFlow 4481724 is the CARB-legal pick for California, Colorado, New York and Maine, while the 49-state 93462 saves you roughly a thousand dollars if you live in a non-CARB state. All three are stainless, spun-body, bolt-in units — no cutting or welding.
Shop Our Top Pick →A failing Honda S2000 catalytic converter is one of the most common reasons a 2000–2009 roadster throws a check-engine light and flunks its smog test — and because the F20C and F22C are among the hottest-running, highest-revving four-cylinders Honda ever built, the factory cat lives a hard life. This guide compares the three MagnaFlow direct-fit converters we stock for the S2000, breaks down which one is legal in your state, and shows you exactly how the 2.0L (AP1) and 2.2L (AP2) fitments differ so you order the right part the first time.
Which MagnaFlow Catalytic Converter Fits Your S2000?
The right converter is set by two things: your model year and the emissions law where you register the car. MagnaFlow splits the S2000 into two fitment ranges — 2000–2005 (OE interchange 18160-PCX-A00) and 2006–2009 (OE interchange 18160-PZX-000) — and within the earlier range you choose between a CARB-compliant California cat and a cheaper 49-state Federal cat. The table below lines up all three so you can match your car in seconds; prices run from around $440 for the Federal unit to roughly $1,510 for the 2.2L California converter.
| Converter | Model Years | Emissions Grade | Legal To Install | Price |
|---|---|---|---|---|
| MagnaFlow 5461261 (2.2L)Top Pick | 2006–2009 | California / CARB | All 50 states | $1,509.00 |
| MagnaFlow 4481724 (2.0L/2.2L) | 2000–2005 | California / CARB | All 50 states | $1,407.00 |
| MagnaFlow 93462 (49-State) | 2000–2005 | Federal / EPA (HM) | Non-CARB states only | $439.00 |
MagnaFlow 5461261 — the CARB-legal converter for the 2006–2009 AP2.
AP1 vs AP2: Why the F20C and F22C Are So Hard on Cats
The S2000 came in two flavors, and the difference decides which converter you buy. In the US, the AP1 (2000–2003) ran the 2.0L F20C, which made 240 hp at 8,300 rpm and 153 lb-ft at 7,500 rpm with a 9,000 rpm redline — roughly 120 hp per liter, a naturally-aspirated production record at launch. The AP2 (2004–2009) switched to the 2.2L F22C1, trading about 800 rpm of redline (down to roughly 8,000 rpm) for stronger low-end torque: 237 hp at 7,800 rpm and 162 lb-ft at 6,800 rpm. Honda also moved to 17-inch wheels and retuned the suspension in 2004.
Both engines spend their lives near the top of the tach, and sustained high rpm means sustained high exhaust-gas temperature. That heat is exactly what cooks a catalytic converter’s ceramic substrate over time. Add 17 to 26 years of age, the occasional misfire, and any oil consumption, and the factory cat eventually loses conversion efficiency. Note the fitment overlap: MagnaFlow’s 2000–2005 converter (part 4481724 / 93462) actually covers both the 2.0L cars and the 2004–2005 2.2L cars, because the split is by exhaust hardware, not engine.
The 2000–2005 MagnaFlow 4481724 uses OE-style flanges and O2 bungs for a true bolt-in fit.
CARB vs Federal (49-State): Which One Is Legal Where You Live?
The single most important choice is emissions grade, because installing the wrong one means an automatic smog failure. A California / CARB-compliant converter is tested to California Air Resources Board standards and carries an EO (Executive Order) number — a CARB certification ID matched to your exact year, make, model and engine, stamped on the body alongside the part number, date and a flow-direction arrow. MagnaFlow’s 4481724, for example, is certified under EO D-193-139. A CARB converter is legal to install in all 50 states.
A Federal / EPA (49-state) converter like the HM-grade 93462 meets federal standards and costs far less — around $439 versus roughly $1,407 for the CARB version — but it is not legal for sale, installation, or use in California or other states that follow CARB catalytic-converter rules, which currently include Colorado, New York and Maine. In California, using a non-CARB cat can trigger a failed smog check, registration problems, and fines cited as high as $25,000 per vehicle. Bottom line: if you register your S2000 in a CARB state, buy the California-grade unit; if you are in one of the 49 non-CARB states, the Federal 93462 is the smart-money pick.
The 49-state MagnaFlow 93462 saves roughly a thousand dollars — but is not legal in California, Colorado, New York or Maine.
Signs Your S2000 Needs a New Catalytic Converter
The clearest signal is diagnostic trouble code P0420 — Catalyst System Efficiency Below Threshold (Bank 1). It means the downstream oxygen sensor is tracking the upstream sensor too closely, so the PCM has decided the converter is no longer scrubbing exhaust efficiently. Other symptoms include a persistent check-engine light (often the only sign), a failed emissions or smog test, a rotten-egg / sulfur smell, a rattle from a broken internal substrate, sluggish throttle response, and slightly lower fuel economy.
Before you replace the cat, rule out the cheap stuff: a lazy or dead O2 sensor, an exhaust leak, misfires (P0300), or a fuel-trim problem can all mimic or accelerate a P0420. If the converter itself is genuinely worn out, an OEM-grade direct-fit replacement restores the conversion efficiency the PCM expects and keeps the light off — something a cheap high-flow race cat often cannot promise.
The Three MagnaFlow S2000 Converters Compared
Every converter below is a genuine MagnaFlow direct-fit unit: a stainless-steel spun body with mandrel-bent piping, OE-position oxygen-sensor bungs, and a single laser-fusion weld that mimics the factory design for leak-free, thermally efficient flow. Each carries MagnaFlow’s 5-year / 50,000-mile limited warranty and installs in the OE location with no cutting or welding.
Key Specifications — MagnaFlow 5461261
Stainless spun body and mandrel-bent piping keep exhaust flow and durability close to OE.
MagnaFlow S2000 Direct-Fit: Pros & Cons
What We Like
- + True direct-fit — bolts into the OE location with no cutting or welding
- + Keeps the check-engine light off and clears P0420 when the cat is the real culprit
- + CARB versions are 50-state legal and carry an EO number for smog checks
- + Stainless spun body with a 5-year / 50,000-mile warranty
Things to Consider
- – CARB-grade converters cost roughly three times the Federal 49-state unit
- – The 93462 cannot be installed in California, Colorado, New York or Maine
- – Diagnose O2 sensors and misfires first — a new cat won’t fix those
How Much Does an S2000 Catalytic Converter Cost?
Expect to pay around $439 for the 49-state Federal MagnaFlow 93462 and roughly $1,407 to $1,509 for the CARB-compliant 4481724 and 5461261. That gap is normal for California-grade converters: they carry heavier precious-metal catalyst loading plus the cost of CARB certification and EO testing. Because all three are direct-fit, professional installation typically adds only about one to two hours of labor, so a shop-installed cat usually lands a few hundred dollars over the part price.
A genuine MagnaFlow direct-fit converter is still well below the price of a Honda OE unit, and the 5-year / 50,000-mile warranty protects the investment. Avoid the temptation of a cheap no-name universal cat: it needs cutting and welding, rarely carries an EO number, and often fails a re-test within a year — especially behind a high-rpm F20C or F22C that runs its catalyst hot. Buying the correct grade once is cheaper than buying twice.
How to Install a Direct-Fit S2000 Catalytic Converter
Because these are direct-fit converters, installation is a moderate DIY job that bolts into the factory location — a shop typically handles it in under two hours. Raise the car on jack stands or ramps, spray the flange nuts and oxygen-sensor threads with penetrating oil, and give it time to work before you turn a wrench.
You will need a socket and ratchet set, a breaker bar, a torque wrench, and a slotted O2-sensor socket so you don’t shear the sensor wires. The S2000 uses an upstream (pre-cat) and a downstream (post-cat) oxygen sensor; you can transfer your existing sensors or fit new ones, and MagnaFlow’s kits include the crush-ring and donut gaskets you need. Apply anti-seize to the hardware, torque the flanges evenly, route the O2 harness away from the hot pipe, and clear the codes so the PCM can re-run its catalyst monitor.
Direct-fit means OE flange spacing and gaskets in the box — no exhaust-shop welding required.
Pairing your new cat with a quality cat-back can wake up the sound without hurting emissions — see our S2000 cat-back exhaust guide, or browse every application in our catalytic converter collection.
Frequently Asked Questions
Will a MagnaFlow direct-fit converter fix a P0420 code on my S2000?
Yes, if a worn-out catalytic converter is the actual cause. The MagnaFlow direct-fit units use an OEM-grade substrate that restores conversion efficiency, which clears the P0420 code and keeps the check-engine light off. First rule out failing oxygen sensors, exhaust leaks and misfires, since those can trigger the same code.
Which MagnaFlow catalytic converter fits a 2007 Honda S2000?
A 2007 S2000 (AP2, 2.2L F22C) uses the MagnaFlow 5461261 California-grade direct-fit converter, which interchanges with OE part 18160-PZX-000 and is legal in all 50 states. It is priced around $1,509 and carries a 5-year / 50,000-mile warranty.
What is the difference between the CARB and 49-state S2000 converters?
The CARB (California-grade) converters, MagnaFlow 4481724 and 5461261, are certified by the California Air Resources Board, carry an EO number, and are legal in all 50 states. The 49-state MagnaFlow 93462 is a Federal / EPA converter that costs far less (around $439) but is not legal in California, Colorado, New York or Maine.
Do I need a CARB-compliant catalytic converter in my state?
You need a CARB-compliant converter if you register your car in California or another state that has adopted CARB catalytic-converter rules, which currently include Colorado, New York and Maine. In the other 49-state (non-CARB) markets, a Federal / EPA converter such as the MagnaFlow 93462 is legal and much cheaper.
Can I install an S2000 catalytic converter myself?
Yes. All three MagnaFlow units are direct-fit, so they bolt into the factory location with no cutting or welding. Budget about two hours, use penetrating oil and a slotted O2-sensor socket, and reuse or replace the upstream and downstream oxygen sensors. The crush-ring and donut gaskets are included.
How long does an S2000 catalytic converter last?
A quality direct-fit or OE S2000 catalytic converter typically lasts well over 100,000 miles, but heat, age, misfires, and oil consumption shorten that life, which is why many 2000-2009 cars are now on their second converter. Fixing misfires and oxygen-sensor faults promptly is the best way to make a new cat last.
Does a new catalytic converter add horsepower to an S2000?
A direct-fit OEM-grade converter is designed to restore, not increase, power. It returns the car to its factory 240 hp (AP1) or 237 hp (AP2) output by fixing the restriction and efficiency loss of a failed cat. For flow gains, pair it with a cat-back exhaust and header rather than expecting the converter alone to add power.
Keep Your S2000 Smog-Legal
Match your year and state to the right MagnaFlow direct-fit converter and shop thousands more parts at NLP Performance.
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