P CODES (POWERTRAIN) P0400 - P0499 P0420

I Have A 2002 With A P0420 Cat Code. The Factory Cat Was Replaced A Couple Of Years Ago After Becoming Clogged, And Had No Issues To Almost...

What All Should I Look At With Cat Code P0420? It Seems To Not Have A Lot Of Power At Times, 02 Sensor Possible. Bank 1? I'm Getting A...

Passed My Smog Test, And Soon After The P0420 Displayed, Took It To Dealership And They Said There Is No Problem With Cat Converter And...

I Have An 03' Cadillac Deville Base Sedan And It Is Throwing The Code P0420 (catalyst System Low Efficiency Bank 1). This Code Just Came Up...

I Want To No Where Is The Three-way Catalytic Converter Bank 1 Located, So I Can Replace It. Getting Code P0420. The Car Runs Fine. I Just...

Car Was Throwing Knock Sensor Codes P0325 And P0330. Check Engine Light On. Car Radio Intermittently Goes Off Then Comes Back On And When...

So, For The Past 4 Months In New England, It’s Obviously Winter And Anytime I Start My Car In The Morning And It’s Below 40 While It...

Been Getting Misfires Recently. First Started With A P0302. Then Changed Out All Spark Plugs And Coil Packs, Then One Day Accelerated And...

I'm Finding Myself In A Pickle And Would Appreciate Advice. I Drive The Vehicle Listed Above With Less Than 100,000 Miles. And Recently...

2006 Grand Caravan 3.8l, 72,000miles. Has A P0420 Code, Catalyst Efficency Below Threshold Bank 1. Would That Be A Up Stream 02 Sensor? I...