I have a 2004 Dakota with the 3.7 V6

For the P0420 code, would changing the converter solve this code?
For the P0302 code, I have changed the plugs and coil and this code came back. What should I do next to fix this code?
Thank you all

 

Moving to second gen Dakota section.

P0420: Changing the cat might fix it..... of course, it might be a failing sensor too....

P0302: Swap the injector on cylinder 2 with one of the others. See if the miss follows the injector. If not, time for a compression test.

 

OK I have switched the number 2 and 4 injectors and the same P0302 code came back,so looks like I have to do a compression test.Is there anything else I could check or do before I do a compression test. The truck does run pretty good, it's just the two codes that keep coming back. I also have not done anything about the P0420 code because of the weather(Don't have a warm garage to work in LOL!) I noticed that if I don't warm up the truck before driving, that's when the code comes back. Any thoughts on that? Thanks again.

 

fix the misfire before doing anything for the p0420. a misfiring engine will cause a cat to fail so fix it first, clear the dtc and monitor for the p0420

the compression test is the corrrect next step
is the misfire only occurring when cold or all the time? if intermitant...with the scan tool....access the freeze frame failure records and note conditions when the engine is setting the p302.
things like coolant temp
engine rpm
open closed loop
these all tell important clues.

 

Hey primem, yes it only occurs when cold. Going to work in the morning I will let the truck warm up for 10-15 minutes before heading to work but after work I will let it idle for a minute or 2 then drive, I get about 100 yards, check engine light comes on check with the scanner and same 2 codes. I've only had the truck for 4 months and previous owner told me about the P0420 code but not the P0302. Looked at some of his old invoices done to the truck and he also had the same 2 codes for about 2 years. He had a garage do maintenance on the truck such as tune up and oil changes but never did anything about the codes.Thanks again primem.

 

Quick question. I was looking at Rockauto for the downstream O2 sensor and they have Downstream Left and Downstream Right. I don't know which one I need. The exhaust pipe after the cat is on the passenger side. Does it mean I need the Downstream Right O2 sensor? Also does anyone know the OE part numbers for the 3 oxygen sensors for my 04 dakota clubcab 4wd V6?

Thanks All

 

left and right for vehicles refers to someone sitting in the drivers seat; left is drivers side, right is passenger side.

could be a lean misfire condition
the 02 sensors are ignored in open loop...when the vehicle is first started....the 02 heaters need to bring them up to temp before they can produce a signal that is useable by the pcm. check to see if the system is in open or closed loop when you drive off.