Buy Mercury Mariner Catalytic Converters

A Mercury Mariner catalytic converter (also called a cat, cat converter, catalytic convertor, emissions converter, or exhaust catalyst) is a metal can in your SUV's exhaust. Inside are tiny honeycomb passages coated with precious metals. As hot exhaust passes through, the converter changes (or ÒconvertsÓ) dirty gases into cleaner ones before they leave the tailpipe. Most modern cats are Òthree-wayÓ units that cut NOx, CO, and unburned hydrocarbons at the same time. Learn the basics in this short explainer from Britannica and this three-way catalyst overview from Nett. (Encyclopedia Britannica, Nett Technologies)

Your Mariner's cat reduces the worst exhaust pollutants:
* NOx → nitrogen (N₂)
* CO → carbon dioxide (CO₂)
* Hydrocarbons (HC) → water (H₂O) + CO₂
That's why oxygen sensors sit before and after the cat-to help the engine computer keep the air-fuel mix on target so the converter can work. (See OBD/readiness info from CARB.)

The Mercury Mariner was sold for model years 2005-2010 (including Hybrid trims). It's closely related to the Ford Escape and Mazda Tribute and uses similar emissions hardware. Model overview.

The ÒcatalystÓ coating uses tiny amounts of platinum-group metals-mainly palladium and rhodium. That's also why cats get stolen: these metals hold value in recycling. Read more about palladium and rhodium in Britannica and Britannica. (Encyclopedia Britannica)

Common warnings include:
* Check Engine light (often code P0420 Òcatalyst efficiency below thresholdÓ). See a plain-English overview at Kelley Blue Book.
* Egg/sulfur smell from the exhaust
* Rattling from the converter (loose substrate)
* Low power or poor fuel economy
Note: A flashing Check Engine light usually means severe misfire, which can overheat and damage the cat-slow down and get service. The EPA explains this warning in its OBD FAQ. (Kbb.com, EPA)

Replacing the cat without fixing why it failed is a waste. Common causes include misfires, a rich mixture, oil/coolant burning, or exhaust leaks ahead of the cat. OBD systems are designed to catch these problems and store codes so techs can diagnose them. (See OBD background from CARB and federal OBD rules in the eCFR.) (ww2.arb.ca.gov, eCFR)

* It's illegal under the Clean Air Act to remove or disable a catalytic converter or to install Òdefeat devices.Ó The EPA's policy and enforcement alerts are here: tampering Q&A and enforcement alert.
* When replacement is needed, the new converter must be appropriate and installed correctly. In some states, only CARB-approved converters are legal (see below). (US EPA)

Federal emissions law provides special coverage for ÒmajorÓ emission parts-catalytic converters, the onboard diagnostic device (OBD), and the engine control unit-for 8 years/80,000 miles (whichever comes first). EPA emissions warranties and 40 CFR Part 85 Subpart V. (US EPA, eCFR)

Live in California, Colorado, Maine, or New York? Replacement cats must be CARB-approved and matched by Executive Order (EO) number to your exact vehicle/engine family. Start with the CARB program page and state guides:
* CARB: Aftermarket Catalytic Converters
* Colorado Reg 20 / Aftermarket Cats
* Maine DEP: AMCC rules
* NY DEC: AMCC guide (ww2.arb.ca.gov, sos.state.co.us, maine.gov, extapps.dec.ny.gov)

To choose a legal, correct cat for a Mariner:

1. Read your Vehicle Emission Control Information (VECI) label under the hood for your emissions certification (ÒFederal/EPAÓ vs ÒCalifornia/CARBÓ) and engine family/test group. Guides: EPA-locate the label and CARB-find your test group.
2. If you're in a CARB state, look up the converter's EO number to confirm it's approved for your exact engine family. Start here: CARB aftermarket program and the install checklist. (US EPA, ww2.arb.ca.gov)

After repairs or a battery disconnect, your Mariner must complete OBD readiness monitors (including the catalyst monitor) before it can pass a smog check. State resources explain how drive cycles help set monitors: BAR OBD test reference and NY DMV ÒNot ReadyÓ guide. (Bureau of Automotive Repair, NY DMV)

Exhaust parts get very hot. Let them cool before touching. Wear eye/hand protection when working under the vehicle. General workshop safety is outlined by OSHA and Canada's CCOHS guidance for garages (hot exhaust caution) is also helpful: CCOHS: servicing vehicles. A flashing Check Engine light signals severe misfire; the EPA advises getting service quickly to avoid catalyst damage. EPA OBD FAQ. (OSHA, ccohs.ca, EPA)

Catalytic converter theft has surged in recent years. To lower your risk, the National Insurance Crime Bureau suggests parking in well-lit areas or secure garages, adding a shield or cage, and etching your VIN on the converter. Tips: NICB release and NICB regional tips. (nicb.org)

1. Scan for codes and fix root causes (misfire, fuel trim, leaks) first.
2. Confirm emissions certification on the VECI label and, in CARB states, verify the EO for your replacement.
3. Use new gaskets/hardware; keep oxygen sensor wiring safe from heat.
4. Clear codes, run a drive cycle, and confirm readiness monitors are complete before testing. State references: BAR drive/readiness notes.

Have your VIN handy and check for open safety recalls (free repairs). Use the official NHTSA recall lookup or the direct VIN tool at vinrcl.safercar.gov. (NHTSA, vinrcl.safercar.gov)

Modern converters can remove well over 90% of key pollutants when everything is working right, which is why keeping your emissions system healthy matters for clean air. (EPA technical materials: EPA catalyst policy docket-performance notes.)

* Cat / Cat converter / Exhaust catalyst / Emissions converter - everyday terms for catalytic converter
* VECI label - under-hood emissions label with engine family and certification
* EO number - CARB Executive Order proving a converter is approved for a specific engine family
* OBD monitor - self-test your car runs to check systems like the catalyst and O₂ sensors

* How a three-way cat works: Nett Inc. guide
* What your VECI label shows: EPA label locator
* CARB aftermarket rules & EO lookup: CARB-Aftermarket Catalytic Converters
* Federal anti-tampering policy: EPA converter Q&A
* Emissions warranties: EPA FAQ | 40 CFR Part 85 Subpart V
* Readiness & drive cycles: BAR OBD reference | NY DMV guide
* Theft prevention: NICB tips

If you'd like, tell me your Mariner's year, engine (2.3L, 2.5L, or 3.0L / Hybrid), and where it's registered. I can tailor the fitment and state-law notes for your exact setup.