I went to advanced auto a couple weeks ago and they checked my SES light codes. The man said it had something to do with my EGR Valve. I put some Seafoam in the break boaster line and in the gas tank. I went back and the two codes (P0420, P0430). Another question. i heard about seafoam messing with the 02 sensors. Could this of caused it?

 

I thought '01s didn't have an EGR?
Seafoam has the possibility of messing with the o2 sensors due to the amount of crap it cleans out. From what I've experienced anyway.

Also...P0420/P0430 are precat issues, no?

 

That's what I know it as.

 

yes they are

 

Oh really? the man at advance told me it was my cat. Is there an o2 sensor in the precat? if so could that be it?

 

I know what 420 code is ...

 

Lol i thought to myself, damn this code is easy to remember.

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

What does this mean?

 

you need to replace your catalytic convers.

I would recomend replacing the front pre-cat first, clear the codes and see if the p0430 returns. If it does, replace the main cat as well.

This is very common. I've done quite a number of these.

 

Or should i try to replace the o2 sensors since i did the seafoam and the carbon could of messed with the sensors. i mean what are the chances of both my cats going out at the same time?

idk if this will change anything but the car only has 115k on it

 

That's a generic diagnosis/definition based on the code. When applied specifically to the Maxima, it's the precat.

 

Follow the advice in post #8. Replace the precat first. He knows what he's talking about. An aftermarket precat is approximately $200 or less.

 

Is the precat the front cat? I was looking at a magnaflow cat for the front and it was over 500$

 

Yes, after the headers before the resonator.

 

but what are the chances of both cats going up at the same time? this all happened after i put seafoam in the brake booster line and in the gas tank. the has 115k on it.

i also read about the ECM might need to be reflashed?

 

I've had both of these codes, and I doubt that you got either one of them because you Seafoamed your engine. Those two codes are quite famous on the 5th Gen Maxima. Look into buying a Y Pipe that should solve your problem. You'll probably need o2 Sims if you go this route though, just ask around, I'm sure someone on here can point you in the right direction. (Maybe you'll have better luck getting answers to your questions than I had)

 

You can get o2 sims and not have to replace the y-pipe. That will fix it. But really it's just tricking the car.

The real solution is a replacement precat.

 

could you link me to one?

 

I was just thinking of a way that would fix the problem and get him some extra power at the same time.

 

I have an Eastern Cat installed in my car.

http://www.autopartswarehouse.com/sk...gs+Best+Seller

 

Well you see money is kinda an issue right now. im only 17 making min wage. I also noticed a decrease in MPG

 

Save up and do it right by replacing the precat.
Get an aftermarket get to increase performance and get 02 sims.
Or get o2 sims only.

Those are pretty much your only options.

 

if ur broke, use non foulers instead of 02 sims. also, remove your pre cats and gut them yourself.

 

If you have the old programming, ECM reprogramming might take care of P0420...

 

i have the same exact codes, running o2 sims, no more light for more than 1000 miles, even pass insp.

 

Vacuum (intake) leak.
Exhaust leak.
Spark Plug condition

3 things you should be checking before you do anything else. Granted the spark plugs are not a simple thing to check ont he firewall side, checknig the front 3 that are easy to get at will tell you if the others are also fouled. If the front 3 are good don't bother checking the back 3.

Vacuum leak will botch O2 readings and could cause this code. Most seafoam IIRC goes in a Vacuum line, I woulddnt be surprised if it was something as simple as you forgetting to plug a line back in or havign a minor leak from tampering with the lines/area.

Exhaust leak is less likely, and you'd probably hear it when the car starts up cold.

 

i changed the spark plugs 2 weeks ago. and how would i check for an exhaust leak? sorry all this is new to me.

 

Also when the rpms go get to like 1000 it makes a beeping noise and under my car i hear a high pitch noise around the rear driverside door.

 

Close the opening of the tailpipe with a rag, or your hands if it's not too hot. Make sure it's airtight. Listen if there's a leak anywhere.

 

Be sure to do this in a well ventilated area.

 

wth, this doesnt sound like a good practice. if theres a leak, you will hear a leak. most people can hear them and cant find them, you cant hear one but you are trying to find it...???

i say scratch the whole exhaust leak idea


those codes are direct catalytic codes, these cars are notorious for bad pre cats, id guess you have bad pre cats. if u dont want to address them and youre car runs fine, put in the non foulers and call it a day... until the cats clog worse and u start losing power

 

Lol. I'd hope so.

Though I agree with you in that most exhaust leaks are very noticeable, this procedure helped me to identify a very small leak in a resonator that was driving me nuts.

 

i think i will replace the pre cat. but anyone know anything about the beeping noise? when it goes past and goes below 1k rpms it makes a beep from the front of the engine. and the high pitch noise seems the get louder the faster i go.

 

make video

 

Well i just got my pre cat in the mail. Where is the the pre cat located? and is it easy to replace? or should i take it to a mechanic to do?

 

i would visually check the cat i hear about seafoam cleaning so well that little things like the 02 sensor can go but i hear it also means the sensor or w.e was gonna go wrong in the near future anyhow

 

thats what i saying. i read that the carbon deposits build up on the 02 sensors. but i already bought the cat

 

Ok so i had the car on ramps and noticed there is an exhaust leak but its near the back. i also fount out where the pre cat is. Could this exhaust leak be the cause of 0420 and 0430

 

I had p0430 code coming and going for the past 6 months. I would clear it and somtimes it would stay off for 300 miles...other times it would come back after 1 drive cycle. After checking injectors...exhaust leaks, etc. I purchased a pre-cat for about $180 and the 02 sensors to go with it for about $120. I replaced the unit myself in about 8 hrs as I am no mechanic. If you do it yourself make sure you have a good deep wall set as you will need it for the two back studs. The other 3 you can get at from above fairly easy. I have not got any codes since I completed the job in mid-september. The p0430 is for the pre-cat and the p0420 is for the rear cat. Maybe you fix that exhaust leak first and clear the code and see what happens...then install the pre-cat if all else fails.

 

I always thought that the P0420 code was for the pre-cat and the P0430 for the rear cat? Can anyone else confirm or deny this?

 

P0430 Catalyst Inefficiency Bank 2
P0420 Catalyst Inefficiency Bank 1