Going for smog but have bad o2 sensors, via vaq-com.
11-13-2007, 05:19 PM
#1
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Going for smog but have bad o2 sensors, via vaq-com.
Could I pass by only replacing the primary's or are the rears as important or more important? I was told to replace the rears first. what do you guys think??
11-13-2007, 05:25 PM
#2
I think this post has no where near enough info for anyone to respond.
So I will just say "no".
Year and engine?
Codes?
Which sensors are "bad"?
How do you know?
What kind of emissions testing do they do in your state?
Year and engine?
Codes?
Which sensors are "bad"?
How do you know?
What kind of emissions testing do they do in your state?
11-13-2007, 06:16 PM
#3
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Re: I think this post has no where near enough info for anyone to respond.
2000 2.7t
vaq-com says all o2's are bad
california smog
could I pass with only primary's replaced?
vaq-com says all o2's are bad
california smog
could I pass with only primary's replaced?
11-14-2007, 12:23 AM
#4
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On that basis, no because the primary sensors adjust the fuel mixture.....
so really there is little chance it will run properly if they have failed. The secondary sensors are only there to check the function of the cats.
If all four have failed, whihc is rare, it suggests there may be a different fault caus them to fail - ie, the may have no feed for the heater elements or there may be wiring damage etc..... but it rare for all four to fail, unless the car has been run on leaded fuel?
If all four have failed, whihc is rare, it suggests there may be a different fault caus them to fail - ie, the may have no feed for the heater elements or there may be wiring damage etc..... but it rare for all four to fail, unless the car has been run on leaded fuel?
11-14-2007, 02:53 AM
#5
Here's a crazy idea:
Why not fix the problem?
It is unlikely that all four sensors are dead. Look elsewhere.
You emissions answer depends on how CA does the test. If they scan the car, it won't pass. It might pass a tailpipe sniff. Just fix it.
It is unlikely that all four sensors are dead. Look elsewhere.
You emissions answer depends on how CA does the test. If they scan the car, it won't pass. It might pass a tailpipe sniff. Just fix it.
11-14-2007, 03:59 AM
#6
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Often the issue is drive-ability as much as emissions
When my o2 sensor (singular usage you'll note) went on my ancient 1991 90q20v, it ran ridiculously cleanly. We thought the machine was broken. But it also ran very poorly; hesitation, bogging, other various faults.
So my advice is get 'em fixed.
That said, the front sensors ( i think) provide the feedback to the mixture control unit. The rear sensors are there to generate a differential reading and thus be able to measure the efficiency with which the cats are working.
note that a rich mixture, caused bya relatively cheap o2 sensor, will eventually destroy a very expensive cat.
Grant
So my advice is get 'em fixed.
That said, the front sensors ( i think) provide the feedback to the mixture control unit. The rear sensors are there to generate a differential reading and thus be able to measure the efficiency with which the cats are working.
note that a rich mixture, caused bya relatively cheap o2 sensor, will eventually destroy a very expensive cat.
Grant
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11-14-2007, 07:30 AM
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yes. So you have two paths:
1. ALl 4 O2 sensors failed, simultaneously, with the same mode of under-reporting mixture (p=low)
--or--
2. Something is making it run rich and possibly placing the O2 sensors in an out-of-range condition so they all show a code (p=high)
Your call :-)
Grant
--or--
2. Something is making it run rich and possibly placing the O2 sensors in an out-of-range condition so they all show a code (p=high)
Your call :-)
Grant