Hey all, I have a 2004 dodge ram 2500, 5.7l Hemi 4wd

I have two codes that just showed up, po157 and po300. The po157 is a O2 sensor and the po300 is a missfire code for multiple cylinders. I changes the O2 sensor and reset the computer, code came back and light back on. The truck got a new fuel pump and filters 10 thousand miles ago, changed spark plugs 1k ago. I am kind of out of ideas, the next thing I was going after is a grounded wire or a bad computer module.
Thanks for any suggestions or anything!

 

O2 cencors should be replaced at 100k, there fairly cheap at rock auto.

 

Check for vacuum leaks. This will affect the o2 sens readouts and may ping as bad. Most common is the hose off the EGR but of course there are all sorts of other possibilities.

 

Alright, that will be where I go. Lets just say that doesn't fix it, where would I go next? chasing wires and maybe even a bad computer?

 

Yeah, check the o2 sens wires for sure. They get damaged often and its' tough to see them. If the voltage isn't correct, it'll send a fail. Do you actually feel/hear the misfires?

 

Yes, on cold start if you let it idle for like 45 seconds it gets really bad. Also taking off from a start the truck shudders and jerks

 

bad mileage? this sounds vac leaky for sure.

 

yes bad gas mileage. I will be looking this weekend for the vacuum leak

 

ok, i wish you good fortune in your search!

 

Fuel filter has been changed and have you checked the fuel pressure?