JDJuniper

So, originally had 420, now also have 430. Searched a ton and it seems that some say sensors others say cat and sensor. Trying to do this on the cheap and I live in a emissions state and test is at end of month.

So, Do I just replace both Bank 2 sensors? Or just one of them? Or bite the bullet and replace cat and sensor.

Car is a 2K1 with 115K and I would most likely sell it in a year or two.

Thanks

foodmanry

iTrader: (15)

You replace the sensor for the bank the code is popping up on; 0420 = bank 1 and 0430 = bank 2. If you are doing it on the cheap then you may want to look into an O2 bypass...I can't remember what it is called, but it basically fools your ECM that your O2 is working fully and within limits. These are cheap, like around $20, and seem to work for the engine light.

If your state does testing on the dyno you will need to make sure your car is very warm just before the testing.

Eirik

iTrader: (2)

Correct. The 420/430 just means that the level of pollutants filtering out of the engine is above the threshold set in the ECU. Some Maximas, supposedly, have tighter tolerances than others.

Using a slightly-modified spark plug spacer, you can pull the O2 sensor out of your exhaust stream a little bit and it will report back to the ECM that everything's hunky-dory.

(How did he make a new thread with only one post?? Was that 15-post-thing removed?)

JDJuniper

Was a member a few years ago....not sure where the post count went, but can assure you this wasn't the first post.

So replace upstream sensor on both banks, correct?

foodmanry

iTrader: (15)

Yes, replace the primary O2 sensor first.

I remembered the name of the O2 bypass, it is called an O2 sim.

Check out this service bulletin.

http://ww2.justanswer.com/uploads/ba...ITB00-054b.pdf

02whitemaximase

iTrader: (38)

No no no, those codes are for inefficient precats not o2 sensors. DO NOT REPLACE OXYGEN SENSORS ESPECIALLY THE PRIMARY ONES!!!! The ecm uses the secondary (downstream) o2 sensors calculate if the precats are inefficient. You have two options. Replace the corresponding bank precat or do the antifouler trick.

LI_Max_WOT

iTrader: (9)

Cheap fix = spark plug defoulers... (possibly two for each o2) but this could kill your mpg and power, by fooling the computer your actually making it run inefficiently

Best fix = buy warpspeed (SS) y-pipe $200 ($275), replace front cat $200, move rear (bank2?) o2 sensor behind the new front cat... you should pass emissions with no problems this way, gain yourself some power, and have the peace of mind that you just bought yourself another couple of years with no worries about cats/o2 sensors... yea so that or just replace both cats if you don't want to go through the hassle of all that

02whitemaximase

iTrader: (38)

The only oxygen sensors that actually have a bearing on mpg are the primaries. The antifoulers on the secondaries has no effect on mpg unless you are referring to clogged cats.

foodmanry

iTrader: (15)

Hmmm....makes sense, but why does the TSB show replacing the primary O2 and not the secondary?

02whitemaximase

iTrader: (38)

Weird, there are specific codes for a failing primary o2 and the 420 and 430 are not one of them. That is for an infiniti the tsb. Maybe there is a difference in ecm.

JDJuniper

Just wanted to provide an update...so after reading everything I could find on this, and using my own past experience I decided on a couple of things:

1) I doubted very seriously that the Catalytics was acutally bad. 2 years ago test was perfect, car runs as good as ever, consistent MPG's over the years, no smells, hesitations or anything to lead me to think the Catalytic was going.

2) That meant in my mind it had to be an O2 sensor. After doing a ton of reading I came away with the fact that the sensors aren't really monitoring gas flows but voltages and inherantly those could alway throw a blip for whatever reason.

So, first decided I was going to replace all 4 sensors...didn't want to leave one and then find out the code came back, so was going to do all of them.

Then decided before doing the sensors why not remove them and inspect them, clean off any deposits and see what happened...only thing wasted would be my time.

However, before I even started that I decided to just clear the ECM by disconnecting the battery and see what that did.

Well, 2 hours go by, I fire up the car and code gone....nothing much there but figured might as well see where this leads me. Did some more research on how long it takes the ECM systems to reset and determined that if you did a bunch of varied driving for ~ an hour it should do it. I set out and drove back roads, stops and starts...fast acceleration and heavy down shifting..then hopped on the highway and cruised at 75-80 (my normal driving speed) then made an effort to cruise at 55-60....still no light.

Decide what the heck, and go to the inspection station - now Maryland might not be Cali, but they are tough on Emissions and Inspections...wasn't holding my breath but figured worst thing is I would get a 1 month extension.

Get in line and waited 15-20 minutes - never turned car off BTW, from initial drive to now standing in line....still no light. Get my turn, pull in, turn off car, connect scanner, start car...scanner downloads info, Maxima PASSED.

Now, the code might throw again in 3 miles or 300...I really don't care. Once again all parameters are well within normal ranges and I bought myself 2 more years. As I stated at the top of the post, I don't plan on keeping the car that much longer at least not as a primary vehicle, but I also don't have to run out and buy a new car today...nor do I have to spend 1K or more to replace parts on a car that's worth 3K just to pass an inspection.

Anyway your mileage may vary, but if you have to pass an inspection you might just want to try it this way....what do you have to lose?

foodmanry

iTrader: (15)

Good to hear this worked for you. There is one risk you run in doing this is NOT PASSING. In California you don't pass the first time then you just go back for a retest, but in other states I have heard you get run up the flagpole and red flagged. Some type of emissions tag or sticker gets thrown on your car. NOt sure if this applies to Maryland, but worth checking out before trying this in the future.

Rods03Max619

iTrader: (5)

So they just check for codes, not Cali at all they check gas tank cap, put you on the rollers and putl a sniffer on the exhaust, and check the codes, pop your hood make sure its all stock or you got a CARB Sticker....