2005 1500 5.7L with a P0420 Code... lil help?

[coastemac]

Hey everyone, brand new here... diggin' the site though.

Just came home from a light trip off-road and now have a Check Engine Light on. Had a code reader on it and it shows P0420. Catalyst System Efficiency Below Threshold, Bank 1.

Now I'm no mechanic, but I'm willing to try to fix something myself. This truck has 70+k on it, and has been running fine up until recently. I've been noticing my mileage decreasing (not that the Hemi doesn't drink enough of the go-go juice on its own...) and I believe its lost some power too. In my neck of the woods, Alaska, there really isn't much here to help me... the few places that are here want to **** you with their prices. We have an Auto Parts store in town that doesn't even have a code reader if that tells you anything...

Anyway, thinking that I should replace the O2 sensors first, and go from there... but I'd love to have some advice from those of you that have "been there and done that."

Please help a new guy out a little... beers are on me if you do.
Thanks in advance everyone !!!

 

[HemiBabe]

Welcome to the site....

Did some research on the web and this is what I found....


These are the only items that will give the code 99.9% of the time.
1. a bad Cat. Convertor
2. a bad downstream O2 sensor ( the one after the cat)
3. damaged wiring to the downstream O2 sensor

 

[coastemac]

Thanks for the info HemiBabe... I'm thinking replacing the Rear O2 would be the most logical first step, and probably the cheapest as well.
I would also like to add that the day before it through me the code I noticed that my truck was low on oil. I added a quart, and kept trucking that day. I've seen NO oil spots/drips on the ground, and it had been a little bit since I checked the oil, due for a change now too.

 

[txbass06]

Welcome to RF
I was going to suggest O2 sensors too


Sent from my iPhone 4 using Tapatalk

 

[CRA Daytona]

I had the same thing at 60,000 miles. Replaced the O/2 sensors and everything was back to normal.

 

[pavester]

i have this code 24/7 but its probably because i dont have any cats

 

[KGBIGCOUNTRY]

They got ya covered, also check to make sure the wiring hasnt touched the exhaust or been snagged.

 

[coastemac]

Sorry to take so long to reply... but I had to get an O2 sensor sent to me. I'm in Alaska and my father sent it to me from Florida, lol. My ship had me out for over a week anyway, so no biggie. Removed the old one and installed the new one this morning and after pulling the positive terminal on my battery... walla... the Check Engine Light is gone. Ran it at idle for just a few, and shut her down. I'll know its gone for good once she's out on the road a bit, but (fingers crossed) its gone.
Thanks for the tips guys and gals... its much appreciated. Now its time to check out more of this nice site !!!

coastemac

 

[lindengauthier420]

p 0420

Hey i have a 2005 dodge hemi and the engine light came on with the code 0420
. The guy i bought it off said its because i have to run octane 89 in it
Is that true or can anyone help me?

 

[lindengauthier420]

I had the same thing at 60,000 miles. Replaced the O/2 sensors and everything was back to normal.

Hey i have that same code to be on for a while p-0420. Can anyone tell me which o2 sensor i would have to change and how much is a new one? Or is something else wrong?

 

[lindengauthier420]

p 0420 HELP!!!!!

Hi i have a 2005 dodge ram hemi with 167000km on it. And this engine light came on with this code p-0420. Its says its a o2 sensor or the cats. Anyone know which one it would be and which one would be cheaper?

 

[lindengauthier420]

I had the same thing at 60,000 miles. Replaced the O/2 sensors and everything was back to normal.

Hey how much is a new o2 sensor?