maxinout93

So I bought my 02 i35 a month ago, check engine light finally comes on with 4 codes pending. I knew there was a bad cat, but didnt know which one. So Ive done some extensive reading here about the po420, which i think is the rear pre cat, I saw one on amazon but unsure of the part number or what it looks like to be exact. The car lacks high end power which is what id like to fix first. THe other 3 codes where p01800, p0340, p0345. Id like to get the full power back and increase the gas mileage, and dont want to just throw parts at it. Suggestions?

DennisMik

iTrader: (2)

Bank 1 is the right side of the engine with cylinders 1, 3 and 5. Cylinder 1 is on the right side of the car (the passenger side).Because the engine is transverse mounted, bank 1 is towards the firewall.

Bank 2 is the left side of the engine with cylinders 2, 4 and 6. Cylinder 2 is on the right side of the engine (the passenger side). Because the engine is transverse mounted, bank 2 is towards the radiator.

The pre-cats are part of the exhaust Y-pipe that connects the exhaust manifolds of the 2 engine banks. The pre-cat for bank 1 is built into the Y-pipe and cannot be replaced without replacing the Y-pipe. The bank 2 pre-cat is a separate replaceable item that bolts on between the y-pipe and the exhaust manifold.

Link to the service manual for your car:
http://boredmder.com/FSMs/Infiniti/I35/2002/

Use this link for your check engine codes:
http://boredmder.com/FSMs/Infiniti/I35/2002/EC.pdf


P0340 - Camshaft position sensor bank 1.
P0345 - Camshaft position sensor bank 2.
See page 329

P0420 - Pre-cat bank 1.
See page 338

P1800 - VIAS control solenoid valve. This is bolted on the intake manifold by the cylinder 2.
See page 676

maxinout93

Thanks for the reply man, but i have the 3.5 engine so I thought that both pre cats were bolted on. basically i thought they could be seperated/ unscrewed from the y pipe and exhaust manifold. correct me if im wrong

DennisMik

iTrader: (2)

What I said is correct. The bank 1 pre-cat is built into the y-pipe and the entire y-pipe will have to be replaced if the pre-cat is bad. the 3.0 engine and the 3.5 engine are the same in this aspect.

maxinout93

oh ok thanks man. Im gonna have to take it to an exhaust shop and see how much its going to be to replace that thing, the y-pipe and the cat, hopefully its not too much $$.

foodmanry

iTrader: (15)

For the cat codes you are better off having the exhaust ship clear out the cats and just install o2 spacers. Of course, that isn't emissions legal but...replacing the cats are going to be $$$$. Probably more than a grand and up to closer to $1500.

If you punch out the cats and install o2 spacers you are out next to nothing, less than $30 for the o2 spacers you need and the labor to punch out the cats. And...never see the codes pop up again. Even if you replace the cats you may see the codes come up again a few years down the road.

maxinout93

Im all for clearing out the pre cats if it does not make the car any louder, but will keep the main cat. But some ive seen on sites like amazon were aftermarket $150 for rear pre cat, $250 for bank 2 precat and a y pipe on ebay was about 150 160ish. Not trying to spend too much as i never did any exhaust work before myself. We dont have emissions here in south carolina though.

foodmanry

iTrader: (15)

It will be a bit louder, but not by much. If you spend the $600 on the parts you may likely find yourself spending another $600 to replace them a couple years down the road for the same issue.

If you want a longer term fix punch out the cats and install the O2 spacers. The reason you punch out the cats is to prevent any of the cat material entering your engine through exhaust manifold (some people think this might happen) and it doesn't block exhaust flow as they wear down and break apart over time.

maxinout93

ok sounds like a good idea, my car already has a sporty sound due to a hole in the exhaust which i can deal with, just dont want it to get any louder. So both pre cats are removeable without having to remove the manifold?

foodmanry

iTrader: (15)

Yes. It will take a bit of effort, but they are removable without taking off exhaust manifold.

Canadian_I35

While you're at it remove the resonator, i've done it on my i35 and the sound is much nicer.

maxinout93

kool i will look into that.

maxinout93

I know this is a dumb question, but can you remove the front precat without jacking the car up, or no. I want to replace the old ones and gut the ones that im taking off.

DennisMik

iTrader: (2)

IIRC, the bolt heads on the exhaust manifold point downward, and working from underneath the car is the easiest. If you are thin enough to slide under the car, then you won't have to jack it up.

maxinout93

gotcha !