Hi Everyone. First post here. I tried searching for this issue, but couldn't find anything that matched. I apologize if this has been answered time and time again.

I'm helping my buddy track down his issues. 2010 F150 with 4.6. Starting running rough. The only code is P0340 - presumably o2 sensors or Cat. The truck has about 250,000. If the cat gave up the ghost I figure it doesn't owe anything to anyone. However I don't want to just throw parts at it. It also has a few pending codes, p0307 - cylinder 7 misfire, p1299 engine overheating condidtion.

My advice to him was start with cleaning the injectors and plugs, he hasn't done them since he bought the truck 10k miles ago. Then move on to o2 sensors and maybe the cat. Also clean the TB and replace the pcv. My background is mainly with toyota's but my first car was a 92 F150 custom with the 5.0, and my dad and I are messing around with an 85 Bronco with a 351. It's nice to be back working with Fords.

 

Your assumption on the cat is wrong according to this.

https://www.obd-codes.com/p0340

 

Fix the hard code first, then worry about the pendings. You have an issue related to the camshaft position sensor, read the article that Roadie linked.

 

Thanks for the replies guys. I really appreciate the help. However I screwed up. The hard code is p0430, not p0340. Wrote it down wrong in my notes. It's a catalytic converter code.

Can you change titles in this board, it would a mod have to do it?

 

that code could be caused by a bad O2 sensor downstream of the cat. But at that mileage, it could be the cat.

 

A P0430 is almost always the cat itself. If it's running rough and seems to be down on power, the cat is probably plugged. A bad downstream O2 sensor won't cause running issues, all it does is monitor the cat efficiency.

 

If I remove the upstream o2 sensor do you think that would let enough exhaust pressure out to fix the running issue? I'm just thinking of a way that I could accurately diagnose the cat without throwing parts at it. I appreciate your help guys.

 

Might help determine if the cat is indeed plugged if you press a gauge to the hole and see how much back pressure there is in front of the cat. You don't want to run the vehicle very long like this. Muffler shops can determine if the cat is plugged very quickly without much expense.