runscottie

Okay, so first off, hello everyone I am new to these forums. I just bought a 2000 Maxima GLE with only 107,000 miles a couple of weeks ago. I live in NYC for school but am a permanent CT resident. I passed emissions and registered it in CT and then BAM, CEL comes on.

The light happened to come on the same day I was planning on taking it to a Firestone (I usually never go to firestone but I had coupons for oil change,brakes and buy 1 get 1 free bosch wiper blades, so I figured what the hey) Since I was there anyway I asked the guy to give me the code. I dropped it off, went to work, then got a call from the mechanic telling me that it was either the Cat or a bad 02 sensor. I figure, what the hey you are in there already do the diagnostics and tell me whats up. Turns out the guy I bought it from had replaced the O2 sensor, but had done so poorly. The mechanic said it was lose and kind of messed up. He says he tightened it up then reset the code, now lets wait to see if the CEL comes back.

Well it did come back, after about 220 miles. So now I'm wondering what do I pursue next?

A) Since it was the previous owner who replaced the 02 sensors, maybe its worth a try replacing the 02 sensor again? Because God knows if he f'd that up?

B) Replace coils/plugs that could be linked to causing the code?

C) Replace the precat?

D) Reset EMU or go to dealership and pay for EMU reprogramming?


I really don't want to go the route of 02 sensor simulation, so thats not an option. Also, btw I have California Emissions Thanks for any replies. I tried to do all my homework before posting but now I have to make some decisions. Money is tight!

CaTalyst.X

iTrader: (6)

I would say the most likely cause is the Precat.

I would try the o2 sensor defouler trick as an easy fix.

Of your options, replace the precat. (Or get headers)

Nothing is wrong with your EMU, or coils.

ATL

sounds to me like the o2 was messed up, which gave u bad readings and threw off your a/f, then that bad a/f ruined the cat. prob need to replace the cat and the sensor

foodmanry

iTrader: (15)

What was loose on the O2 sensor? Was it loose at the exhaust bung, or at the electrical connection?

It seems to me a new pre-cat is needed since the previous owner apparently changed out the O2 sensor. He likely saw the same code, changed the O2 sensor, and now it has come back unfortunately for you.

runscottie

Hey thanks for the replies everyone. So, based on what I'm seeing here I should probably replace both the 02 sensor AND the pre-cat right?

I've been looking around and I think I'm gonna go for a Walker pre-cat. Seems to be the best deal I can find for a California emissions car.

For the 02 sensor, the mechanic made it sound like the electrical connection was loose. I've heard Bosch is good for 02 sensors? Any recommendations for the 02 sensor?

BigLou55

iTrader: (6)

yea got with Bosch, its what the dealer uses also but getting it at an autoparts store will be cheaper. My car is cali emissions as well and I found the eastern catalytic(my bank 2 is this brand) to be the cheapest but there is nothing wrong with walker(I have that on my bank 1). I wouldn't go with an evans fischer though, I've read reviews on the sites that carried that brand and several people complained about fitment issues. good luck

nishfish871

iTrader: (5)

If no sniffer test, drop the Y and hit the front precat with a hammer a few times. Magic dust will come out. Install the spark plug nonfouler mod, and enjoy the added performance and reduced engine wear.

You have just done half of the gutted precats mod. The rear precat is a BISH to even get off to gut or replace.

foodmanry

iTrader: (15)

He's got a point here. It depends on the type of emissions test. If no sniffer test then you can gut both pre-cats and go the non fouler mod and be done with it. The rear pre-cat (y-pipe) isn't THAT hard to remove...you just need to jack up the car very high and PB blast the nuts before working to remove it.

However, with a sniffer test you'll have to replace the offending pre-cat and O2 sensor.

runscottie

Hmm... well the car needs to pass Emissions in CT. Not sure if CT is a "sniffer" test...

As for the pre-cat + 02 sensor replacement option: follow up question.

Do I just replace the bank 2 sensor or do I need to replace ALL of the 02 sensors?

foodmanry

iTrader: (15)

Find that out first because if no sniffer test life will be a lot easier and cheaper for you. I'm sure you can check online on the CT DMV web site.

As far as replacing the O2 sensors you only need to replace the front sensor for that pre-cat. Since it is bank 2, you replace the front pre-cat (smaller one) and the O2 sensor in front of it (heated O2 sensor).

You can also use a code scanner that reads live data and test the cat for functionality per the FSM. Although, I've never done this, but may be useful for you to determine if it is the cat or O2 sensor. Check out the link below.

http://www.nicoclub.com/Matt/p0430.pdf

In this link you can access and download the FSM for your Maxima. Keep in mind there are two FSM's for 2000 model. I was informed it depends on your VIN number.

http://boredmder.com/FSMs/Nissan/Maxima/

To check your VIN against the proper FSM go to this web site below.

http://www.aubreyandcharles.com/ServiceManuals/

GeorgeWho

I too had the dreaded P0430 code on my 2000 GLE which had 109,000 miles on it when i bought the car used. In an effort to fix the problem, i replaced the Bank 1 and Bank 2 02 sensors after reading several posts online as to possible fixes. This did not fix the problem so i then moved on to the next step which was to replace my spark plugs. At this point my car had approximately 150,000 miles on it. This still did not fix my problem, so i took out the Battery, removed the air intake box(black box located next to the battery) which includes the Air Filter and MAF Sensor. Once i removed the battery, it was easy to remove the Air intake box as it is held in place by five screws, and by a clamp holding the MAF to the rest of the engine. I could not get the MAF loose from the Air intake box as the clip would not release so i just removed the two screws holding down the MAF to the Air Intake box, pulled out the MAF sensor itself and wrapped it in a piece of paper towel. My next step was to properly clean out the Air intake box of all debris which had a lot of leaves and dirt, and this was accomplished by using my leaf blower to blast the inside of it, then once i felt all the dust was out, i sprayed the inside of the box with some CRC Mass Air flow cleaner and used that to get rid of the fine dust particles that remained, making sure to spray a good amount onto the fine mesh wire inside the box so that all dust particles were removed, and finally setting the box down to let it drain of all the CRC MAF cleaner. While the box was drying, I just used a can of compressed air to blow out any dust residue in my air filter, because it was still relatively new and i did not want to replace it. Next and final step was to use the CRC MAF Cleaner to spay and clean the MAF sensor which i held onto while spraying it liberally several times with the cleaner. Once i was satisfied that it was clean, i put back all the components, and then after i felt the sensor was dry, slide it back in place in the MAF box and tightened back up the two screws holding it in place. I got kind of lucky here as i did not remember in which direction the sensor was supposed to face, but one rusty screw i remembered was facing one direction so i put it back using that as my guide. After all is said and done, I have driven the car almost 160 miles so far with no annoying check engine light, and all it required was me cleaning the MAF. If it comes back i will follow up with a post. Please note that while I was spraying the MAF Cleaner onto the MAF Sensor, it was still attached to the engine so all I did was to spray the cleaner onto everything except the top of the Sensor itself which had the brown clip and wire holding it to the engine.

GeorgeWho

Update....The Service Engine Soon light came back on after 286 miles so i tried removing the MAF sensor only and spraying it with the cleaning fluid but the light did not go out. Could be that the first time out when i did this having the battery out reset the codes and cleaning the MAF might have helped too but now its back to square one. I am gonna go back to Autozone and have them do a free diagnostic check just to see if its the same P0430 code.

altezzablazes

I used oxygen sensor spacers. Thats what i used when i gutted my pre cats. no more p0430 and p0420.