P0420 trouble code
07-25-10, 07:12 AM
#2
Super Moderator
Welcome to the Club.
There's a few ways, but it's really going to depend on your equipment that you can have or get access to.
From experience, this is usually something to do with the gas you just bought. In Mexico, PO420 was a common problem for a lot of cars given gas quality. However, sometimes, as I found out last week with my RX300 (that runs a similar 1MZFE motor to your ES300), not peeking around the corner to see the tanker truck was filling up the station, lead to a couple of issues for me, a P0420 and also a random misfire P0300 (your CEL flashes when this occurred). I then thought back immediately to the Chevron station I had just filled up at and noticed the tank around the corner as I was leaving. Thus, I was getting some of the gas at the bottom of the tank.
However, when I got home, I hooked up my diagnostic software (via laptop) to my computer and could tell that although my two a/f sensors up front (bank 1, sensor 1 and bank 2, sensor 1 were okay), the bank 1, sensor 2 O2 sensor (same one as in your case) was getting readings that were out of bounds and thus causing the P0420. That has since passed. Some mechanics will have access to such software through either a laptop or a more advanced OBD2 scanner that can see if you are getting in-spec readings with bank 1, sensor 2.
There is another way to actually take some electrical diagnostic equipment to see if the the sensor is faulty, but the method I just mentioned is easier.
I am not sure what part of Texas you are in, but if you are in an area with emissions testing, some mechanics may have a a gas analysis machine (akin to checking emissions) and they can see what readings you get for various things, particularly HC (hydrocarbons) and tell that way if the cat may be bust or going on the way out.
I can say that from general experience, P0420 codes can also be a mixed of getting very hot air through the intake mixing in the combustion cycle and not producing a clean burn, thus producing a P0420.
Clearing the code and then filling up and seeing if it comes back may or may not help clear it, but sometimes that is the case.
There's a few ways, but it's really going to depend on your equipment that you can have or get access to.
From experience, this is usually something to do with the gas you just bought. In Mexico, PO420 was a common problem for a lot of cars given gas quality. However, sometimes, as I found out last week with my RX300 (that runs a similar 1MZFE motor to your ES300), not peeking around the corner to see the tanker truck was filling up the station, lead to a couple of issues for me, a P0420 and also a random misfire P0300 (your CEL flashes when this occurred). I then thought back immediately to the Chevron station I had just filled up at and noticed the tank around the corner as I was leaving. Thus, I was getting some of the gas at the bottom of the tank.
However, when I got home, I hooked up my diagnostic software (via laptop) to my computer and could tell that although my two a/f sensors up front (bank 1, sensor 1 and bank 2, sensor 1 were okay), the bank 1, sensor 2 O2 sensor (same one as in your case) was getting readings that were out of bounds and thus causing the P0420. That has since passed. Some mechanics will have access to such software through either a laptop or a more advanced OBD2 scanner that can see if you are getting in-spec readings with bank 1, sensor 2.
There is another way to actually take some electrical diagnostic equipment to see if the the sensor is faulty, but the method I just mentioned is easier.
I am not sure what part of Texas you are in, but if you are in an area with emissions testing, some mechanics may have a a gas analysis machine (akin to checking emissions) and they can see what readings you get for various things, particularly HC (hydrocarbons) and tell that way if the cat may be bust or going on the way out.
I can say that from general experience, P0420 codes can also be a mixed of getting very hot air through the intake mixing in the combustion cycle and not producing a clean burn, thus producing a P0420.
Clearing the code and then filling up and seeing if it comes back may or may not help clear it, but sometimes that is the case.
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