[Kenny Rochester]

I have a 2005 Nissan Titan LE Gas w/ 197,000 miles throwing a Bank 2 knock sensor code and a cat below threshold on bank 2. I had the exhaust manifolds replaced last year w/ Dormans. So I really don't think that the cats are stopped up. Could the knock sensor be causing the cat code? First time I took it to the shop they said cat 1 and cat 2 where below threshold (i knew cat 2 was throwing the code that was the reason for it to go to the shop but that was the first time cat 1 threw a code) and the knock sensor code but the found a loose pcv hose and tightened it up, cleared the codes, watched everything and it seemed fine. Well I picked it up and drove 17 miles. Bam light back on so I took it back to the shop now they are saying all 4 o2 sensors are bad and of course the knock sensor also. Both times they said run seafoam and it should be fine. I don't know about that. Opinions?

 

[dubyam]

I suspect your Dorman manifolds are failing, though the knock sensor is a different issue, possibly. I know the Frontiers at one time had huge problems with knock sensor failures. I'm not even sure where our knock sensors are on the Titans.

 

[Nick Name]

Cats don't report codes. That code comes from the ECU reading an out of spec between the pre and aft O2 sensors. What's the condition of those? They are easy to test with a multimeter, but if they've never been changed out, that's your most likely culprit just due to your mileage...or ..... if you used non OEM new ones when you did the manifolds. Test them and go from there. That may also clear your knock sensor and you're good to go. Solve one problem at a time...assess....repeat if necessary.

Do not put Seafoam into anything!! Seafoam is oil with a bit of rubbing alcohol like the doctor uses to clean where you are going to get a shot....it is not a chemical brew. The O2 sensors won't like that at all. It has the same effect downstream as bad rings...including the smoke cloud. Get a new mechanic if he's telling you to use that stuff. Consider that not a single auto manufacturer recommends Seafoam, Miracle Oil, etc. for anything. Only Seafoam recommends Seafoam.

 

[Kenny Rochester]

I know all about Seafoam, Lucas, and etc. There is a reason that the owner's manual says not to use any kind of additives. The code was a p0430 which is bank 2 catalytic converter is below threshold. Everything that I am reading is saying the knock sensor is the main culprit. The o2 sensors were replaced when the manifold were replaced. All with OEM sensors which are Bosch. The knock sensor code didn't show up for me because it won't show up on a generic scanner. The knock sensor is the easiest and cheapest fix so I think I am going to start there. BTW I've never had a Nissan service center tell me to put additives in but the Ford service center did and I told him the owner's manual says not to. He wanted to argue with me about it so I got my manual and showed him. I've never been back. Oh back pressure tested fine.

 

[Nissan-MasterTech]

The knock sensor is a non check engine light code, meaning the KS will not turn on the light if it's the ONLY code in the system. In your case the P0430 code turned on the light , the KS code was just along for the ride so to speak.

The 430 code is most likely due to the aftermarket cat you put on it . I know OEM is expensive but they will last longer than an aftermarket one.