Hi All,
Just came back from the inspection station in NH and they said the car would not pass emissions because of "Ready Monitors Not Ready".
Right before I went to the inspection I cleared the code that was stored in the computer. Code P420.
So does someone know how long it takes before the ready monitors become ready?
I read here that the code P420 could be caused by a too low threshold which can be corrected by having the computer re-flashed. Is that true?
I have 60 days to have this problem fixed.
Thanks in advance.
-quadcells

 

They should all be ready/run after 1/2 hour of driving IIRC.

They should know this, go drive for a bit and bring it somewhere else.

 

Same thing happened to me in my S10 a while ago when I had it, I had cleared a code that morning and only put about 20 miles on the truck before getting it inspected and a few tests weren't ready. 1/2 hour is not guaranteed to do it, mine needed about 100+ miles of driving before all monitors were ready to be tested.

 

The "not ready" message came up because you cleared your codes right before going. It actually may or may not go away after 1/2 hour of driving; it really depends on how you drive, because the conditions need to vary in terms of acceleration, cruising, etc for the ECM to return to a state of readiness.

 

Btw, there is detailed information on the System Readiness Test (SRT) code in the FSM, including what driving patterns are required for the system to complete self diagnosis and return to an emissions ready state.

 

damn technology....makes things so complicated..

 

I had no engine light until 1 week after I replaced the MAF sensor. I did not have the computer re-programed. Could that be the reason I am getting this P0420 code?
I am still waiting to here from the Nissan dealer about re-flashing the computer.
-quadcells

 

It's detailed in your Owner's Manual. Near the back........check the index. The P0420 code is the cat. function code. Could be several things including intake air leaks. Check the MAF/intake duct clamps etc. for "snugness" etc. What year is the car?

 

I just change the MAF, I will check the ducts. It's a 2000 SE

 

You do not need to re-flash the ECU after the new MAF, if you really want to you can disconnect the battery for a few hours and the ECU will "re-set" and relearn.

 

this happens when you disconnect your battery, nothing is wrong with the cat. the monitor just needs to reset its self and may take some time. i was looking at a maxima from a dealer and the check engine light was on and i had it looked at by my mechanic and the dealer tried to wipe the computer and so the mointor hadn't reset, casuing the check engine light to come on. hope that helps.

 

FTR, clearing codes via battery takes SEVERAL DAYS on a maxi.

Your readiness moniters aren't ready because the ecu hasn't finished each of it's self tests, catalyst efficiency being one of them, what this basically means is that you may very well have the code pop up again shortly.

In my experience, about 80% of the time this code has come up it was from a faulty o2 sensor (pre OR post cat!!) that for some reason didn't trip an O2 code, BUT, out of all of those times that a cat efficiency code came up from a bad O2, when the O2's were removed the bad one was identifiable by shaking the o2 sensor it would rattle inside, that may not always be the case, but so far it has been for me.

 

Page 10-21 of the owners manual has the "READINESS FOR INSPECTION/MAINTENANCE (I/M) TEST" steps. The P0420 is likely the black wired O2 sensor (B1S2, IIRC).

 

Did you replace just the MAF sensor or the whole MAF assembly including the housing and sensor? And, why was it replaced?

 

Correct, it is bank 1 (firewall side) but it could be either pre or post cat o2 sensor.

 

I have been able to get all of my monitors to run in 15 minutes...

 

Hi All,
Well it has been a very expensive time at the dealer. I talked to the service manager first and didn't get very far. I asked to talk to their "Master Technician" about this P0420 and the TSB about it. He explained to me that it applies to certain ECU's. He pulled the ECU numbers and showed me the TSB and that my ECU was not one of them. He also went thru all the steps to see if it was an O2 sensor or the cat. The tech proved to me that it was indeed the cat and that driving the car with a bad MAF could cause the failure to the cat by allowing un-burned gas to reach the cat. He also said that you do have to reprogram the ECU after replacing the MAF to get the right air to gas mixture. I was satisfied with his explanation but not satisfied with the bill.
They did give me a 10% senior discount (I am 45 but the service manager said that the little gray in my mustache would do. lol)
Well now I got to go back to the inspection garage and have them do the emissions so I can get my sticker.
Side note: I think it's great that they have a 8yr 80,000 mile warrantee on the cat, but since the repair is so $$$ for something you must have in order to get a sticker, you should be able to get some kind of pro rate bill depending how old the car is. Sorry, just rambling.
-quadcells

 

Quad, was year was your Maxima? Next, was your ECU original programming (i.e. what came with the car?) or had it been updated more recently than that?

 

2000 SE, I do not know if it was the original program.

 

I don't know about there but in PA and MD if you show up multiple time with a not ready and you swear you didn't do anything to it they usually pass you the second time. My girlfriends Suzuki Forenza was a car that truely would never go ready. After finding out that they just passed it the second time I had my buddy try it in MD and the same time they gave him a waiver to pass that one and come back in two years when it's time again. Usually just BS'ing with the dirtiest tech's at the stations you'll find out all the secrets on how to pass.

 

Hi,
First tank full of gas after cat and re-programming and now I am getting 2mpg more then before. Also it feels like it has more power.
I think I need new tires. These tires brake lose way too much. They really suck in the rain.
What are good all season tires for this car for around $130-$150per.
-quadcells

 

For get that,
I went with the Michelin Pilot Sport A/S.