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P0420 Toyota Corolla 2003


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GeO2110
New User

Aug 8, 2012, 12:30 PM

Post #1 of 7 (18165 views)
  post locked   post icon P0420 Toyota Corolla 2003  

Hello to everyone, I found this site in my search to found a solution to a P0420.

2003
Toyota
Corolla
1.8l (1ZZ)
88k miles.


This car is from USA, but it is now in Guatemala where I live. Yesterday check for the codes and the freeze frame data. ---------------------------------------------
Service $02 - Freeze Frame Report
---------------------------------------------
Date: 07/08/2012 21:41:39

PID Description Value Units
--- ----------- ---- -----
0x02 Freeze frame DTC P0420
0x03 Fuel system status Closed-loop, using oxygen sensor feedback to determine fuel mix
0x04 Calculated load value 50.98 %
0x05 Engine coolant temperature 199.4 F
0x06 Short term fuel % trim - Bank 1 1.56 %
0x07 Long term fuel % trim - Bank 1 -3.12 %
0x0C Engine RPM 2343.75 RPM
0x0D Vehicle speed 38.53 MPH
0x0F Intake air temperature 80.6 F

This is the info that I get from a short trip, after erase the original code.












Regards.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 8, 2012, 12:44 PM

Post #2 of 7 (18139 views)
  post locked   Re: P0420 Toyota Corolla 2003  

Check with the dealer for an update computer flash for that and you may have to replace the cat but only use dealer cats on that one.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



GeO2110
New User

Aug 8, 2012, 1:04 PM

Post #3 of 7 (18133 views)
  post locked   Re: P0420 Toyota Corolla 2003  

Hi, here is almost impossible to ask to dealer for an computer update, they simply don't know anything about. The dealer cat is at US$ 2,400, so it is almost illogic to go with them.

At this point, what I was unable to answer is that the short term fuel trim of Sensor 2 is ok to be at -1, in all the conditions. The O2 sensor 2 y different than the O2 sensor 1, so I suppose that the cat is doing its job. I can't find any info to check that the STF should moving, as its just for check the cat.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 8, 2012, 1:32 PM

Post #4 of 7 (18124 views)
  post locked   Re: P0420 Toyota Corolla 2003  

I understand you got a new toy but believe me, your info doesn't mean a thing for that code. If you want to waste your money on an aftermarket cat, go right ahead but I'm in the business and Toyota uses a larger capacity cat and the aftermarkets always have a problem. If you don't want to look into the reflash, then you're pretty much wasting every one's time here.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Aug 8, 2012, 4:10 PM

Post #5 of 7 (18112 views)
  post locked   Re: P0420 Toyota Corolla 2003  

Those are nice snap shots.

If you took that long snap shot while driving, I'd say the converter isn't doing much.

The O2 sensor voltages tells you something is wrong. If the converter was working and the engine was at operating temperature the B1S2 should be almost flatline. There looks to be a lot of inversions going on.

The fuel trim looks great. As long as the long term fuel trim is staying between -9 and +9 % the computer isn't over compensating for a problem.

What you could do is take a shorter snap shot, but of one just with the front and rear O2 sensor voltages. Get the engine up to operating temperature and then hold the engine around 2500 rpm in park. Snap the voltages and compare them.





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cja9500
New User

Oct 3, 2012, 6:19 PM

Post #6 of 7 (17776 views)
  post locked   Re: P0420 Toyota Corolla 2003  

I just fixed the P0420 code on my '03 corolla le. The car ran fine, but it wouldn't pass PA inspection due to the CEL being on. Toyota wanted me to spend serious money to fix this, again the car ran fine!! Found out by internet search that there are these things called Technical service bulletins (TSB), put out by the NTSB (goverment). you can sign up at alldatadiy.com to actually read the bulletins.. it cost me around $25 for a year. Anyway, the TSB says to replace the cat and re-flash the ecm. I you tube searched how to clean the cat and poured a gallon of lacquer thinner into a 1/2 tank of gas and ran the car hard until tank was close to empty. There were no adverse effects and I haven't had any problems, I did this over 2 months ago now. This did not get the CEL to go out, because the ecm has to be reflashed. I could not find a non-Toyota dealer with the machine to do this for me. When I called the dealer, to ask them about the TSB and if they would re-flash it for me, they insisted in diagnosing the car and charging $85 to do so. Then came all the bull about O2 sensors and multiple catalytic converters on the car...Blah..Blah..Blah..
I talked to my mechanic and he called the dealer in front of me and asked them to re-flash the ecm for him (his shop). My guy made the mistake of not calling me back, so I proceeded to call the dealer and posed as Chris from "John's Auto", this got me into the dealer minus the $85 diagnosis fee. Took more bull at the dealer, "There is no need to re-flash an ecm to fix a p0420 code" I told them to look it up, they did, and at least that know-it all shut up. Next the manager told me re-flashing the ecm without replacing the cat may cause the car to run very bad. At this point, I no longer cared, and had it re-flashed for $95. The car ran fine, it is still running fine. It passed inspection and no more light. The answer as right in the TSB!!, but the dealer did not even check or it!! A little research can go a long way!! I'm going to post this in other threads as well, so no one has to go through what I went through, or get ripped off. You could put in a new cat but if you have an 03-04 corolla with this problem, the light will just come back on... Hope this helps someone.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 3, 2012, 7:18 PM

Post #7 of 7 (17772 views)
  post locked   Re: P0420 Toyota Corolla 2003  

The reflash and cat replacement from the TSB was posted to the original poster long ago and that advice has not changed.

Your distrust of the dealer and home remedies have no place in this advice forum. This is already an old thread and you shouldn't be responding to it at all.
This thread is closed now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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