LazYRaCeR

I keep getting a P0420 error code and I thought it was my aftermarket intake. I installed the stock airbox and the light came back on. I noticed my power steering fluid was low when I was working on the car so I refilled it and in two weeks it was almost empty. I noticed a puddle of something under the car I assume would be power steering fluid. It says on the little print out from the error check at auto zone that the possible cause could be a "large vacuum leak", does anyone have any experience? I looked at the hoses coming out of the little reservoir and no leak, it seems like it's leaking from the other end of the fat hose that's closer to the middle of the engine, its a bastard to get to so I can't confirm. Any suggestions on what to do?

kingkai1990

I'm getting the same thing, except I'm also getting a P0128, p0011. Meh.

maxiiiboy

P0420 complains about the efficiency of your Bank 1 pre-cat. However, your description also indicates that your Power Steering (PS) hose is also leaking. If so, it's likely that the PS fluid is dripping on, and damaging your B1 O2 sensor. This may confuse the ECU so that it generates a "false" p0420 " code you are seeing.

You get the picture. It's time top stop the PS leak, and then replace the O2 sensor. Then, re-evaluate.

foodmanry

iTrader: (15)

While an interesting notion this is doubtful. At any rate, the OP needs to check for PS leak (likely from the hose as this is a trend with these cars) and fix the PS leak first.

After you tackle the PS leak you can clear the SES light and see if it comes back with the P0420. I almost guarantee you it will come back since it is a known issue with these maximas. You can try replacing the O2 sensor (secondary on bank 1) and clear the engine light. If the code still comes back then you have a problem with the pre-cat. If it is ultimately the pre-cat then you can either replace it (lots of $$$), install an O2 sim (not smog compliant/legal and you have to do wiring), or install an O2 spacer.

When I had my last P0430 code which is the same as P0420, but on bank 2. I installed an O2 spacer and it took care of the issue. I wasn't going to drop a few hundred or more just to replace the pre-cat.

LazYRaCeR

Thanks guys, any information on an 02 spacer? I haven't heard of it.

foodmanry

iTrader: (15)

Here you go...this is the one I ordered and put in. A bit of a tight fit, but it fits.

maxinout93

But what if the op installs a spacer, and the code po420 pops back up, and it is indeed a bad pre-cat??

Turbonut

That's what the spark plug non-foulers are for, to eliminate the CEL when the cat is bad.
Put a front cat on the daughter's car (P0420) and 8 months later it returned. Installed the non-foulers and haven't seen the code since and that's been 4 years ago.

Child_uv_KoRn

iTrader: (7)

That's the problem when replacing cats..they will just fail, again, and you're back to square one.

It feels so good dumping that crap in the trash

LazYRaCeR

thanks guys!

maxinout93

U guys are making me lean more and more towards just gutting the cats on my car. I just dont want to mess with any rewiring of the 02 sensors.

maxinout93

U guys are making me lean more and more towards just gutting the cats on my car. I just dont want to mess with any rewiring of the 02 sensors.

Turbonut

Gutting the cats will not change or eliminate the code, but if you don't have the code, after gutting you will.

The addition of the non-foulers does not require any rewire, just drill one out, install inside the other and install in exhaust. The cats are great when they function properly, but as I've found over the years, and as Child_uv_KoRn stated, the aftermarket cats do not have a long life and the OEM cats are priced out of site. The upstream OEM cats can be had for @ $1500 which is really ridiculous, then add in the main for good measure, another $700.
Spend $1500 on the upstream cats, or $20 bucks for non-foulers if both are bad.

Nothing new as this problem has been around for years, so you might want to do some searching.

LazYRaCeR

If it's the cat I am in trouble because just for the part itself is ~$1000 and thats not including labor. Now to figure out how to fix this leak, replacing the 02 sensor I can probably do, but I just hope it's not the cat.

maxinout93

Not really, you dont have to buy OEM if you replace them, there are aftermarket cats to on amazon or ebay, just depends on what brand you want to get.

foodmanry

iTrader: (15)

It is unlikely. The O2 spacer works a majority of the time. Besides it is a cheap way to find out.

foodmanry

iTrader: (15)

Jesus...have you not been reading the thread? Install an O2 spacer and be done with it.

LazYRaCeR

So fix the PS leak, clear the code. If it doesn't work replace 02 sensor and clear the code. If it doesn't work it's probably the cat so try a spacer and clear the code. My only worry is that the spacer won't work and I'll have to replace the cat (which I might just try an aftermarket one). Well, at least I have a plan of action.

foodmanry

iTrader: (15)

Yes...so you waste $15 and 30 minutes of your time if the spacer doesn't work? Better than replacing the cat if you don't have to....

maxinout93

well i too have the 420 code pop up, everytime i scan the codes on my car and erase it, 420 pops right back up. If you are not yet experiencing a loss of power, or cat rattling then maybe you should just replace the 02 sensor if you havent done so yet, and if the code comes bak, take it to a shop and let them run a test on exhaust back pressure, some can tell you indeed if the cat is bad or not. I have a host of exhaust issues, flex pipe is broken, heat sheilds are loose, as well as a bad cat smell, so Ive got my work cut out, not gonna ignore the check engine light if the problem is well known on these cars if i plan to keep it for a little while. Other than that car runs fine. But if you just install a spacer and dont really take care of the problem its like ignoring what your car really has going on.

Turbonut

The car is telling you that there is problem with the cat, so it seems as though we're making a mountain out of a mole hill. Most would see the P0420 when the cat is just plain worn out and not able to "clean" the exhaust, but the vehicle continues to operate properly, so the easiest and least expensive fix is to just use the non-foulers. If a cat is clogged, one would certainly experience operating issues as well as other codes.

Donkeypunch

The car is telling you it's p0420 time to blaze it phaggot.

maxinout93

yeah thats what i mean by using the spacers if the problem isnt fixed, like putting a bandaid over it.