I have a check engine light which denoted the following code P0420. Anyone has any clue? This is in a 2009 Dodge Grand Caravan. Would this be the O2 sensors or the CAT? Please help. Thanks

 

most cat efficiency codes are due to tired old cats. If the 02 sensors are switching properly, its needs a cat.
sometimes when people install a new rear 02 and the front 02 is old and lazy, switching slowly, it can set a false p0420 dtc. if that in not the case you probably need a cat. Do not install a cheap cat or the p0420 will reset.

 

X2 but want to add just try resetting the code. Last two times I saw that code I just reset it with a scanner and never saw it again.

https://www.obd-codes.com/p0420

 

It's most often a bad cat, but you must find out what killed it before replacing or you'll dill the new one too

http://ricksfreeautorepairadvice.com...ix-code-p0420/

 

I have a 2010, always serviced, always use premium gas and I tripped this code. Meanwhile, my 2005 trips no codes. 7 years is not that old, do these cats fail often?

 

save you money and use regular grade fuel.

cats usually have a long life. they can be damaged by misfire conditions, have their lives shortened by exhaust leaks or bad 02 sensors, head gasket leaking coolant.

 

Just to let you know that I just fixed the P0420 code on my 2005 Dodge Grand Caravan this weekend. I only need to replace the downstream O2 sensor + adding the check engine light eliminator adapter (cost ~ $30 total). The youtube link is as below if you are still interested: https://www.youtube.com/watch?v=qkhDeOvvvX0&t=324s

 

just to be clear...
installing an antifowler just masks the rear 02 from the exhaust stream. It fixes the symptom but doesn't fix the problem...if the cat was at fault...after this repair it still will not be working and would not pass a gas analyzer emission test.

its an inexpensive fix but pollutes and would be illegal for a shop to perform.