Bought the truck for my Son one year ago. '99 Ram 1500 , 115k miles, 5.2l.

Replaced the factory Cat shortly after w/ a Magnaflow cat. Then about 6 months later truck threw a P0420 code. My search here and the local Dodge dealer said Cat was out. I changed the 02 sensors no change and the Cat was warranted.. Now it's doing the same thing again??

Anyone have the same happen?? Any experience or input greatly appreciated?? Maybe the injectors . The first cat did have some discoloration, due to heat ,know it's getting to much unburnt fuel to the cat. What could be the problem??

Got to change out the ball joints this week. Wasn't expecting this problem to show back up.

TIA.

 

Anyone????

 

May be a possibility.. get a scanner or something to check fuel pressure, timing. Not heard of them buring out that quick. Try searching the forums maybe there might be someone with similar problems

 

You could have a miss. You could have a really bad plenum gasket.

 

ya know, my plenum smelled like a tank of gas. idk if that's normal, but it was intense lol. my cat rattles at idle so i figure that the plenum was part of it, if not the only reason. after that then i'm gettin one of those magnaflow's, so keep posting on what you find out. May be you just got the one bad 6 mo cat that magnaflow made at that time.

 

Antifreeze will kill it , unburnt fuel will kill it over time , MHO

 

A really bad plenum would allow all kinds of fluids, oil, antifreeze, fuel to get caught up in there. Geez I see why it's such a necessary fix.

 

How so? Oil, yeah. Are we talking about the plenum gasket?

 

i have a similar problem and hopefully i'll find some answers. mine is a 00 ram 5.9l that I purchased in oct. 06. Last summer i took the factory cat off and it was completely melted inside... the honeycomb did not exist, it was just one big blog of meltedness. I replaced it with a magnaflow 3" high flow and my mpg almost doubled. Well recently my mpg has gone back down to where it was before and my cat is no longer sealing at the "input" clamp... which is making me think that this cat is melted as well. I am thinking that mine is running rich (obviously) but I am unsure as to why it is, or how to fix it. I have a feeling that my plenum is no good, but we wont know that til this summer. Good luck on your truck.. and maybe i'll get lucky with some info from here.
Thanks

Kenny

 

yes gasket. IDK man, my pan had other stuff other than oil lol. the gasket was broken in two sections. Glad I'm doing this work before I do the cat/glasspack.