A6 with possible cat problems
04-06-2012, 06:26 AM
#11
Often secondary O2 sensors after cat
My 01 2.7t throws this occasionally and so far have been clearing codes as needed. Many have solved this issue by replacing the secondary O2 sensors, since your cats are probably still OK.
Others have put the O2 sensor extender on, which is what folks who remove the cats use.
When my codes become more frequent, I'm going to replace the post cat O2 sensors. they are easier to get at than the pre-cat sensors.
Others have put the O2 sensor extender on, which is what folks who remove the cats use.
When my codes become more frequent, I'm going to replace the post cat O2 sensors. they are easier to get at than the pre-cat sensors.
04-06-2012, 07:03 AM
#12
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one of two problems:
1. an 02 sensor is out of calibration and must be repalced ( or likely, more than one)
2. A cat (or two) is dying
Let me explain roughly how it works. There is an 02 sensor before and after the cat. The improvement should be X. If it is less than X, the cat is not doing its job to specs. OR the measurement is off (or, on an old car, both...)
I suspect both.
The key, on a 145k car, is to get the thing through inspection. Replacing cats on an old car is being too good a citizen, IMO.
G
1. an 02 sensor is out of calibration and must be repalced ( or likely, more than one)
2. A cat (or two) is dying
Let me explain roughly how it works. There is an 02 sensor before and after the cat. The improvement should be X. If it is less than X, the cat is not doing its job to specs. OR the measurement is off (or, on an old car, both...)
I suspect both.
The key, on a 145k car, is to get the thing through inspection. Replacing cats on an old car is being too good a citizen, IMO.
G
04-06-2012, 05:49 PM
#14
AudiWorld Super User
Agreed
one of two problems:
1. an 02 sensor is out of calibration and must be repalced ( or likely, more than one)
2. A cat (or two) is dying
Let me explain roughly how it works. There is an 02 sensor before and after the cat. The improvement should be X. If it is less than X, the cat is not doing its job to specs. OR the measurement is off (or, on an old car, both...)
I suspect both.
The key, on a 145k car, is to get the thing through inspection. Replacing cats on an old car is being too good a citizen, IMO.
G
1. an 02 sensor is out of calibration and must be repalced ( or likely, more than one)
2. A cat (or two) is dying
Let me explain roughly how it works. There is an 02 sensor before and after the cat. The improvement should be X. If it is less than X, the cat is not doing its job to specs. OR the measurement is off (or, on an old car, both...)
I suspect both.
The key, on a 145k car, is to get the thing through inspection. Replacing cats on an old car is being too good a citizen, IMO.
G
04-08-2012, 06:35 PM
#16
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I just got around to reading it all after busy couple days.
I understand that i have four o2 sensors and that their purpose is to keep the readings between the two in a certain range.
The engine light is actually off right now that it is getting warmer around here. I have found that it will mostly stay on when it is colder out. Does anyone know if that is an indication of anything? Because I don't think is a winter gas problem.
I understand that i have four o2 sensors and that their purpose is to keep the readings between the two in a certain range.
The engine light is actually off right now that it is getting warmer around here. I have found that it will mostly stay on when it is colder out. Does anyone know if that is an indication of anything? Because I don't think is a winter gas problem.
04-09-2012, 04:34 AM
#19
It's the efficiency of the cats that going. They are not "cleaning up" the exhaust as good as they used to. Performance is not affected unless they are coming apart and clogging the exhaust.
04-09-2012, 06:34 AM
#20
I don't think it's the Cats. Have any O2 sensors ever been replaced? I'm still thinking downstream O2 sensors.
Have you given the Cats a whack to see if they rattle and are starting to fall apart? Also, check the Flex pipe ahead of the Cats for leaks.
Have you given the Cats a whack to see if they rattle and are starting to fall apart? Also, check the Flex pipe ahead of the Cats for leaks.