Pending P0420 for 7000 miles

[Dlundgren97]

So it getting time to get an inspection again and for the past 7000 miles i have had a pending p0420.

I have a 97 camry 2.2 with 139,000 on the clock and is a california emissions model.
I first got a check engine light at around 132,000. I got my scanner and pulled a the codes: P0420 (catalyst inefficientcy) P0170 (lean code) and a toyota only code P1133 (code for air fuel curcuit response). I replaced the front o2 sensor (Air/fuel sensor) and cleared the codes and the check engine light went away and has since stayed off. I scanned the car a few days later and found that i still had a PENDING P0420. i decided to wait it out and see if the code would mature into a real code and trigger a check engine light. nope. Now over 7000 miles later (and approx. 8 months) with no check engine light the pending P0420 is still being pulled when i scan it.

Since then i have not cleared code or pulled the battery to make the ecm relearn anthing, ive just left it alone, figured i would just worry about it around inspection time and now it is now coming up fast.

Now im kind of stumped on what to do now since im pretty sure i wont pass MA inspection with a pending code. Any thoughts?

[fenixus]

time to replace all oxygen sensors. california specs uses Air Fuel Ratio sensors (wide band) upstream (around $100 new Denso OE from amazon or ebay) and the rear sensor under car (used for monitoring catalyst efficiency) is a regular oxygen sensor, around $70 off amazon or ebay.

AFR sensor:
Denso 234-9024

post-cat (rear) o2 sensor:
Denso 234-4137

get those replaced first. double check part numbers for the car here:
http://www.densoaftermarket.com/cata....php?part=afrs

then look for those on amazon and get them done. might wanna do the tune up too, new NGK Iridium-IX spark plugs and NGK TE58 wireset, new OEM fuel filter, fresh air filter

EDIT:
replace the rear oxygen sensor now. just realized you did already the AFR

[Dlundgren97]

Thanks for the input fenixus. The plugs and wires were done at around 122,000 i believe so i think they got some life left still. Might check them out anyways. Im going to clear the code and resest the ecm probably some time tommorow and see what happens. Maybe is was a fluke?? **wishful thinking** haha. But if it comes back, which it probably will, il definatly look into changing out that downstream o2 sensor. It definatly makes sense that it could be dirty and giving a false reading considering how burt out the A/F sensor looked when i changed that.

Any other thoughts?

[Dlundgren97]

bump. Any one else had this problem before?

[Dlundgren97]

So i got my inspection sticker the other day. I ended up clearing the pending code and it hasnt come back in about two weeks. Im guessing the code might have been thrown once when the car was relearning the correct air fuel ratio for the first time after the new A/F sensor was put in. Now like clockwork my cousins 98 camry need the same sensor replaced at 120,000 but hey atleast it is a quick fix.

P.s. sorry for the late response

[JohnGD]

Yes, oxygen sensors do not last forever. Some unfortunate owners actually paid for new catalytic converters.

But always make sure the engine is well tuned - timing belt, spark plugs, valve clearances, no air/vacuum leaks etc.

[Dlundgren97]

Of course gotta keep the camry happy. The thing that gets me is that I reviewed the inpection form from last year and my catalyst monitor wasnt ready when i passed inspection that time. Now over two weeks after the code was cleared again it still has not readied. As a matter of fact the whole year ive owned the car the cat monitor hasnt set!

Im thinking the downstream O2 is on its way out slowly but i dont know. Not worried though because in MA the catalyst monitor not being ready only matters if it failed emissions for a cat code in the past. Thats why I made damn sure that no inspection station was going to see that pending p0420 and possibly trying to pawn off a $1200 cat job on me haha. Man i love loop holes, feel bad for those who ended up paying that didnt need one.

[BamZipPow]

Find a shop with a smoke machine (that knows how to use it) and have them check yer system fer vacuum and exhaust leaks...

[Dlundgren97]

I believe the flange in between the front exhaust pipe and rear needs a new gasket. I got my exhaust repaired back last year and the guy said that although he fixed the leak he noticed the flange was still leaking a little bit. Not enough to hear it though (idling or flooring it) i guess.

[BamZipPow]

http://www.smokewizard.com/
http://www.smokewizard.com/resources/videos/#exhaust