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Discussion Starter · #1 ·
New to the forum and cant seem to find any info on this code, I will go back and look again but when I searched on here I got google search results. My car went for a smog with the codes wiped off the night before. When I got the smog it passed with flying colors out the pipe but could not complete the smog because the sensors were not reset yet. The code is p0420, all roads lead to the cat but my question is why would it be blowing clean air if bad. Any advice will be greatly appreciated.
 

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Any advice will be greatly appreciated.
(The following is "If that code is what I think it is; I have no reference handy to look it up but others have had similar experiences.)

This is a little extra "trick" they added to prevent exactly what you DID; that is, purposely resetting the codes right before a test. :eek:

It does not necessarily mean that anything is wrong, just that it hasn't gone enough miles since the last reset for the readings to be considered valid.

All you can do at this point is drive it normally....and hope the "invalid" code goes away before your inspection sticker exprires.

I'm somewhat puzzled that the place that did your inspection didn't tell you that.
 

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Discussion Starter · #3 ·
There is something wrong, the code came back after the car was driven for a while. From what I can find it is the cat, not sure which one. Any more thoughts would really help, the car is on a dmv extension so I can sort this out.
 

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The O2 Sensor might not be reading correctly. Or the Cat is starting to malfunction. P0420 is "Catalyst Below Threshold" The Temperature is read by the O2. I have seen this code come up A lot on Toyota cars. Usually needing the Cat replaced.


After a Reset of the Code. You would get a P1000. System Checks Incomplete. From not driving enough since Reset.
 
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