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P0420, P0400 and P0303 on 1999 Mistubishi Gallant ES
The Mitsubishi Gallant ES has 262,000 miles on it. Been getting the P0420 catalyst efficiency below threshold for about a year, year and a half. I know that's due to burning o...
1999 Mitsubishi Galant ES | P0303P0420 Fault on 1999 Chevrolet Camaro V6: Causes and Warranty Coverage
I recently received a P0420 diagnostic code on my 1999 Chevrolet Camaro with a 6-cylinder engine. The code appeared just a few days ago, and while the car still runs smoothly wi...
'99 Camaro v6 | P04202000 Chevrolet Suburban 5.3L - P0300 Random Misfire and P0420 Catalyst Efficiency Issue
My 2000 Chevrolet Suburban with a 5.3L V8 engine has been experiencing difficulty starting, especially in cold weather over the past few years, with occasional issues during hot...
2000 suburban 5.3 | P03001997 GMC Sierra P0420 and P0430 OBD2 Codes: Causes and Solutions for Catalytic Converter Issues
I recently received P0420 and P0430 diagnostic codes on my 1997 GMC Sierra with a 5.7L V8 engine. After clearing the P0420 code, it reappeared after approximately 100 miles, fol...
1997 GMC Sierra | P04201999 Ford Escort Engine Won't Start: Fixing P1506, P0171, and P0420 Codes
I own a 1999 Ford Escort with a non-original 4-cylinder engine that has recently stopped running. After retrieving the trouble codes using an OBD-II scanner, I found three key e...
99 Ford Escort | P0171PO420 Fault on 1998 Honda Accord 2.2L EX: Aftermarket Cat Replacement Dilemma
Installed a new Walker aftermarket catalytic converter in February, direct fit model. Recently the vehicle triggered a PO420 code (Catalyst System Efficiency Below Threshold). A...
98 Accord 2.2 EX | P04201996 Ford Explorer XLT 4.0L EFI - P0420 Code After Smog Pass and Coolant Leak Concern
Hello everyone, I recently encountered a check engine light on my 1996 Ford Explorer XLT with the 4.0L EFI engine, triggering Diagnostic Trouble Code (DTC) P0420. The issue app...
1996 Ford Explorer XLT | P04202003 Honda Civic SI P0420 Code: Causes, Repair Needed, and Long-Term Damage?
My 2003 Honda Civic SI is frequently throwing a P0420 diagnostic trouble code. It recently passed its emissions test in May 2008 and runs smoothly under normal conditions. I'm c...
2003 Honda Civic Sir | P04202005 Chevrolet Colorado P0300 Random Misfire: Causes, Fixes & Warranty Coverage
Two months ago I purchased a 2005 Chevrolet Colorado 2WD with a 2.8L engine and 5-speed transmission. When inspecting it on the lot, the MIL (Check Engine) light was already on....
Chevy Colorado | P0300How to Fix P0420 and P0507 Codes on 2003 Nissan Altima 2.5L: Vacuum Leak vs Catalytic Converter Failure
My 2003 Nissan Altima 2.5L has been showing a check engine light, and after testing at AutoZone, I received two trouble codes: P0420 and P0507. P0420 - Catalytic Converter Effi...
2003 Nissan Altima | P0420P0420 Code on 2000 Toyota Corolla: Is the Catalytic Converter Really Faulty? A Real-World Diagnosis
Hello everyone, This is my first post in this community, and I'm sharing a real-life experience with a common issue that many owners of older Toyota Corollas face — the P0420 d...
Unknown | P0420P0420 Fault on 2005 Honda Odyssey (41,000 Miles) - Causes and Repair Solutions
I recently purchased a used 2005 Honda Odyssey with only 41,000 miles. Shortly after driving it off the lot, the check engine light activated. Using my Actron PocketScan, I retr...
2005 Honda Odyssey | P0420Saturn L200 2.2L Ecotech Engine: P0420 and P0170 Codes After Cat Replacement
I own a 2003-2005 Saturn L200 with the 2.2L 4-cylinder Ecotech engine. I recently replaced the original catalytic converter, which had become plugged, with a new unit from CATCO...
Saturn L200 | P017298 Toyota Sonoma 2.2L Catalytic Converter Differential Temperature Normal Range and Diagnosis
I have a 1998 Toyota Sonoma with a 2.2L engine. What should the normal differential temperature be between the catalytic converter inlet and outlet? After a 45-minute drive home...
Cat | P0420P0420 and P0135 Diagnostic for 2003 Jeep Wrangler 4.0L Six-Cylinder
My 2003 Jeep Wrangler with a 4.0L six-cylinder engine has recently triggered two OBD-II diagnostic codes: P0135 and P0420. The vehicle runs smoothly with no noticeable performan...
2003 Jeep Wrangler | P0420PO135B & PO420 Fault: Rear O2 Sensor Heater Issue on 2002 Chevy Prizm 1.8L Auto with 102K Miles
Hi OBD2 community, I'm troubleshooting a 2002 Chevrolet Prizm 1.8L automatic 3-speed with 102,000 miles. The issue began when the vehicle failed emissions inspection due to per...
Unknown | P0420