P CODES (POWERTRAIN) P0400 - P0499 P0420 Questions

Engine Light Came On.. This Is The Code That Came Up. Two Days Later The Light Went Off On Its Own. I Made An Appointment To Have The Part...

I Am Still Receiving A P420 Code After Replacing The Entire Exhaust System Including The Exhaust Pipe, Cat Converter, O2 Sensors Before And...

Took Car To Autozone And Got This Code, Definition Is Catalyst Efficiency Low Bank 1. What Does It Mean And How Can I Fix It To Pass...

Hello! I Have A Mazda Protege 99 1.6l. I Have The Cel On Since I Got The Car. Butt I Failed Do Replace The O2 In Time And Now It Sais The...

I Have Replaced All The Cat's (3) And The Same Code Still Comes Up. I Will Be Checking For Leaks, But I Dont Think That Is It. Took It To...

Hi, I've Been Having The Same Problem With This Car For Maybe A Few Weeks Now And Cant Figure Out What It Is. I Checked All The Vacumm Lines...

Can Too Much Back Pressure Caused By A New Midpipe Cause A False P0420 Code?

I Have A 98 Pontiac Thansport, It Has A P0420 Code I Cant Figure Out What I Would Look For In The #1 Bank Doug

I Have A Dodge Caravan 2002 With A Code Po420 What Does That Mean? Runs Fine, No Noices

P0420 Code On 2001 Mitsubishi Galant