I've got these codes currently and my economy is suffering.
I've replaced the upstream O2 sensors, and will be doing the downstream probably on tuesday.... but I'm aware that this may not be the problem.

I do have an exhaust leak at the drivers side manifold, but it stops when it gets hot, and an exhaust leak on one side wouldn't affect both right? I'll be fixing the leak as soon as I can get headers for my truck.

That being said, What else could cause a catalyst system inefficiency on BOTH sides?

It's odd because I can't see the O2 sensors both going bad at the same time, but maybe it didn't happen at the same time, I just got the truck with these codes already.

 

Have you had a chat with the dealer you bought it from about that? Seems to me, that is something they should have addressed while they had it.

If you are getting cat codes on both sides, I would suspect a fueling issue. Either too much, or not enough. It *may* be related to old/slow pre-cat sensors.... or, your cats may be hollow...... Have you checked fuel pressure?

 

I just might give them a call, but no I haven't checked fuel pressure....not sure how I do that or what I need to do it.

I just replaced the pre-cat sensors, then the code went from pending to stored after I went on about a 30 min drive.
I don't think they're hollow, it's got stock exhaust and nothing has been cut or anything so it doesn't look like someone hollowed them out.

I do also have 2 new pacesetter high flow cars coming, but there's no point in replacing those if the problem is elsewhere and it's going to cause those to fail as well.

 

Should just need the fuel pressure gauge. I think there is a schraeder valve somewhere on the fuel rail for just such a purpose. You can rent the gauge from your local parts store.

Wouldn't hurt to look at inlet/outlet temps of the cat either. Outlet temps should be around 100 degrees warmer.

 

I'll probably just buy a gauge set, it's like $60 and probably worth having.

I'm just waiting for some money to come in and then I'll probably be downstairs checking this stuff out.

What should fuel pressure be, or is there somewhere to find that information?

 

You should probably pick up a real factory service manual for your truck. You can likely download one from amazon, or ebay, for 30 bucks or so. More information than you will ever want.

 

I downloaded the PDF so I have all 8414 pages of the manual lol.
I looked on ebay to see if I could get a paper copy because I like to have a physical book, but jesus christ, like $600-$800 for 4 thick as books lol.

 

That's why I have a laptop. Not quite as convenient as a paper manual, but, not nearly so bulky, or expensive either.

 

So I checked my fuel pressure and I'm getting 56PSI, KOEO, and 60PSI with the engine running.
I'm concerned now because I've read it's supposed to be 58PSI and 70PSI.

Could mean the fuel filter needs changing?? which means dropping the gas tank and replacing the whole fuel pump right?

 

nope.... remembered wrong from what I read.

Alldata apparently says it's 58PSI +/-2PSI, and 60PSI running, +/-2PSI.

So I guess I'm good in that regard.