Exhaust repair guides
Symptoms, check engine codes and comparisons, explained plainly, with sources.
Symptoms and problems
Bad Catalytic Converter Symptoms: 7 Signs, What Else Causes Them, and How to Tell
The common signs of a failing catalytic converter, the other problems that look the same, and a simple order of checks before replacing it.
Bad Exhaust Flex Pipe Symptoms: Noise, Leaks and When to Replace It
How a failing exhaust flex pipe sounds and looks, why it fails, how to confirm it, and whether to repair or replace it.
Bad Muffler Symptoms: Loud Exhaust, Rattling, Rust and Condensation
The signs of a failing muffler, what causes them, how to check yours, and what to look for in a replacement.
How to Test for a Clogged Catalytic Converter
The symptoms of a clogged or restricted catalytic converter and the tests shops use to confirm it: vacuum, backpressure, temperature and the tap test.
Exhaust Leak and Carbon Monoxide: Warning Signs and When to Stop Driving
Why an exhaust leak can be dangerous, the carbon monoxide symptoms the CDC lists, and what to do right away if you suspect a leak.
Exhaust Ticking Noise When Cold That Goes Away When Warm
Why an exhaust manifold or manifold converter leak often ticks on a cold start and quiets down as the engine warms, how to tell it from engine noise, and what to check.
Rattling Under the Car at Startup: Heat Shield, Converter or Hanger?
How to tell the common causes of a rattle under the car apart: loose heat shields, a broken catalytic converter core, and worn exhaust hangers, with simple checks.
Rotten Egg Smell From the Exhaust: What It Means and What to Check
Why a car exhaust can smell like rotten eggs or sulfur, how it connects to the catalytic converter, the other possible sources, and what to check first.
Check engine codes
Flashing Check Engine Light: Why It Can Ruin Your Catalytic Converter
What a flashing check engine light usually means, why misfires overheat and damage catalytic converters, and what to do right away.
New Catalytic Converter but Still Getting P0420? Here Is Why
The common reasons P0420 or P0430 comes back after a catalytic converter replacement, from exhaust leaks and oxygen sensors to engine problems and readiness, and what to check.
P0420 Code: Catalyst Efficiency Below Threshold (Bank 1), Causes and What to Check First
What the P0420 check engine code means, why it is not always a bad catalytic converter, and the order to check things before you buy a new converter.
P0430 Code: Catalyst Efficiency Below Threshold (Bank 2), and How It Differs From P0420
What P0430 means on V6 and V8 engines, why it points at the bank 2 converter, and what to rule out before replacing it.
Readiness Monitors Explained: Why Your Car Is "Not Ready" for an Emissions Test
What OBD II readiness monitors are, why they reset after a repair or battery disconnect, how many can be not ready in Texas, and how to get them ready.
Comparisons
409 vs 304 Stainless Steel Exhaust: Rust, Strength and What You Are Really Paying For
How 409 and 304 stainless steel compare for exhaust parts: chromium and nickel content, surface rust, lifespan factors and cost.
Direct-Fit vs Universal Catalytic Converter: Which Should You Buy?
A side-by-side comparison of direct-fit and universal catalytic converters: installation, fit, total cost, sensor ports and the rules that apply.
How-to and buying guides
Bank 1 vs Bank 2 Explained: Which Side Is Which, and Why It Matters for Your Converter
What bank 1 and bank 2 mean on V6 and V8 engines, how sensor 1 and sensor 2 fit in, and how to find the right side before ordering a part.
Exhaust System Parts Explained, From the Engine to the Tailpipe
A plain-English walk through every part of a car exhaust system in order: manifold, flex pipe, catalytic converter, oxygen sensors, resonator, muffler, gaskets, clamps and hangers.
How Long Does a Catalytic Converter Last, and What Kills One Early?
How long catalytic converters normally last, the engine problems that ruin them early, and the habits that help a converter reach full life.
How to Find Your Engine Size Before Ordering Exhaust Parts (4 Free Ways)
Four free ways to confirm your engine size, including NHTSA's official VIN decoder, and why engine size matters so much for exhaust parts.
Upstream vs Downstream Oxygen Sensors: What Each One Does
The difference between the upstream (before the converter) and downstream (after the converter) oxygen sensors, how they judge your catalytic converter, and what to check when one fails.
Vehicle guides
2011-2019 Dodge Journey 3.6L V6 Flex Pipe Guide (and Which Journey Recalls Apply)
Front flex pipe guide for the 2011-2019 Dodge Journey 3.6L V6 front-wheel drive: exact fit by trim, signs of a leak, and which Journey emissions recalls and notices apply to the 3.6L.
2006-2011 Honda Civic 1.8L and Civic Hybrid 1.3L Muffler Guide
Rear muffler guide for the 2006-2011 Honda Civic 1.8L and Civic Hybrid 1.3L: exact fit, which Civics it does not fit, signs the muffler is failing, recalls and why 304 stainless matters.
Hyundai Elantra Flex Pipe Guide: 2011-2016 Elantra 1.8L, 2013 Coupe and 2014-2016 Elantra GT 2.0L
Front flex pipe guide for the 2011-2016 Hyundai Elantra 1.8L, 2013 Elantra Coupe 1.8L and 2014-2016 Elantra GT 2.0L: the exact engine and body combinations, signs of a leak, recalls and what to check.
2007-2020 Mitsubishi Outlander 3.0L V6 Flex Pipe Guide
Front flex pipe guide for the 2007-2020 Mitsubishi Outlander 3.0L V6, front-wheel and all-wheel drive: what the flex pipe does on a transverse V6, signs it is leaking, recalls and what to check.
2007-2013 Mitsubishi Outlander 3.0L V6 Muffler Guide
Rear muffler guide for the 2007-2013 Mitsubishi Outlander 3.0L V6, front-wheel and all-wheel drive: exact fit, signs the muffler is done, recalls, and what to check before buying.
Toyota 4Runner, Tacoma and FJ Cruiser 4.0L V6 Manifold Catalytic Converters Guide
Manifold catalytic converter guide for the 2003-2009 4Runner, 2005-2011 Tacoma and 2007-2009 FJ Cruiser 4.0L V6: why the converter is part of the manifold, ticking leaks, codes, recalls and what to check.
2003-2008 Toyota Corolla 1.8L Catalytic Converter Guide (Also Matrix and Vibe), and How It Differs From 2009+
Front catalytic converter guide for the 2003-2008 Corolla, Matrix and Pontiac Vibe 1.8L front-wheel drive: exact fit, the 2008 vs 2009 split, recalls, emissions tests and what to check first.
2009-2013 Toyota Corolla 1.8L Catalytic Converter Guide (Also Matrix and Vibe)
Front catalytic converter guide for the 2009-2013 Corolla 1.8L, 2009-2011 Matrix 1.8L and 2009-2010 Pontiac Vibe 1.8L: exact fit, how to confirm your engine, recalls, warranty and what to check first.
Toyota Tundra 5.7L (2007-2019) and Sequoia 5.7L (2008-2011) Catalytic Converters Guide
Catalytic converter guide for the 2007-2019 Tundra 5.7L and 2008-2011 Sequoia 5.7L V8: why there are two, P0420 vs P0430, warranty on late-model trucks, recalls and what to check first.