Need help
01-23-2011, 11:20 AM
#1
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Need help
I have a 2004 A8L 90,000 miles 4.2 engine. Recently I had mass air flow sensor dtc plus O2 dtc my mechanic ( non audi mechanic ) told me the mass air flow is probably the problem. I replace it with a oem one. A week later the check engine light reappeared. Now I have 4 dtcs ;16555 to lean bank 1 , 16556 to rich bank 1 , 16558 to lean bank 2 , 16559 to rich bank 2 . My mechanic said I should probably go to an Audi dealership because he does not have all the diagnostic tools they have. The nearest Audi dealer is at 4 hour drive from my home. I can not beleive all four O2 sensors went bad at the same time. Any help would be appreciated.
01-23-2011, 12:00 PM
#2
I have a 2004 A8L 90,000 miles 4.2 engine. Recently I had mass air flow sensor dtc plus O2 dtc my mechanic ( non audi mechanic ) told me the mass air flow is probably the problem. I replace it with a oem one. A week later the check engine light reappeared. Now I have 4 dtcs ;16555 to lean bank 1 , 16556 to rich bank 1 , 16558 to lean bank 2 , 16559 to rich bank 2 . My mechanic said I should probably go to an Audi dealership because he does not have all the diagnostic tools they have. The nearest Audi dealer is at 4 hour drive from my home. I can not beleive all four O2 sensors went bad at the same time. Any help would be appreciated.
In this place you will find a lot of advised about how to fix it even in a cheap way with ideas that most members just pull out of theirs hats.
first I would like to see a reading of channel 32 of measuring values after you driven the car for a while, need you to run the test on channel 70 and 71 of basic settings.
Need to know the engine load at idle with all accessories off.
34,36, 46 readings would help too
one important thing is to check the intake actuators in front of the engine, your intake manifold may be broken.
01-23-2011, 02:12 PM
#3
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Before you start throwing parts at it find a good mechanic that knows the car.
In this place you will find a lot of advised about how to fix it even in a cheap way with ideas that most members just pull out of theirs hats.
first I would like to see a reading of channel 32 of measuring values after you driven the car for a while, need you to run the test on channel 70 and 71 of basic settings.
Need to know the engine load at idle with all accessories off.
34,36, 46 readings would help too
one important thing is to check the intake actuators in front of the engine, your intake manifold may be broken.
In this place you will find a lot of advised about how to fix it even in a cheap way with ideas that most members just pull out of theirs hats.
first I would like to see a reading of channel 32 of measuring values after you driven the car for a while, need you to run the test on channel 70 and 71 of basic settings.
Need to know the engine load at idle with all accessories off.
34,36, 46 readings would help too
one important thing is to check the intake actuators in front of the engine, your intake manifold may be broken.
01-23-2011, 03:17 PM
#4
AudiWorld Super User
Seems more like a connector that is corroded, not fully seated, broken wire or possibly a defective engine ECU. However, these engine ECU's are pretty bullet proof.
01-23-2011, 03:46 PM
#5
Mass air sensor codes are rarely a result of a failed mass air sensor. The code is triggered when the PCM sees the sensor reporting a value out of it's allowed "window" for any given rpm/ load.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.
Last edited by Mike_k; 01-23-2011 at 03:51 PM.
01-23-2011, 05:02 PM
#6
Common sense
Mass air sensor codes are rarely a result of a failed mass air sensor. The code is triggered when the PCM sees the sensor reporting a value out of it's allowed "window" for any given rpm/ load.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.
finally we getting somewhere, tell the things you know without suggesting possibilities and without gathering plenty of info like most members here.
I can take and appreciate any criticism I get as longest it makes sense, in no way am the only one with auto knowledge here but c'mon have you read lately the kind of post we get here?
this is the A8 forum, not how to mickey mouse and A8 forum
look at the suggestions some member post like live with it, jb weld.
I sympathized with anybody on more important things in life but just because you bought a crappy car and cry about it won't happen,
i like the explanation you stated about the issue at hand and makes perfect sense, before start spending unnecessary parts guessing and maybe fixing the problem.
Sorry back to the Thread! laters,
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01-23-2011, 06:04 PM
#8
Chuckle
Chuckle ***** boy chuckle,
is the only thing we can do when no longer in control, specially for a control freak like yourself.
glad to see we got rid of stupid over glorifying signatures with all the cheap mods we done to our cars,
the forum got cleaner as well as it seems members refrain from crying or writing things without any support or enough knowledge behind their words.
glad to see it come to this point, we can all contribute to the community together on subjects that make sense.
am sure there's drama forums in the net where one can go and cry and other people will feel sorry.
next time don't go nosing in my shop and disclose the lawn chair publicly if you don't want to hear my side and the way I think.
but all in all I think the forum gain an amazing amount of cleaning so it will be more useful in the future, If I helped to get there some people may like it some don't but from time to time is necessary to shake things up.
even though I have time to hang here I have better things to do with my time like growing my business, so relax you may not see me here much in the future.
is one of those things, if you danced on the last one you will sit on this.
is the only thing we can do when no longer in control, specially for a control freak like yourself.
glad to see we got rid of stupid over glorifying signatures with all the cheap mods we done to our cars,
the forum got cleaner as well as it seems members refrain from crying or writing things without any support or enough knowledge behind their words.
glad to see it come to this point, we can all contribute to the community together on subjects that make sense.
am sure there's drama forums in the net where one can go and cry and other people will feel sorry.
next time don't go nosing in my shop and disclose the lawn chair publicly if you don't want to hear my side and the way I think.
but all in all I think the forum gain an amazing amount of cleaning so it will be more useful in the future, If I helped to get there some people may like it some don't but from time to time is necessary to shake things up.
even though I have time to hang here I have better things to do with my time like growing my business, so relax you may not see me here much in the future.
is one of those things, if you danced on the last one you will sit on this.
01-23-2011, 07:25 PM
#10
Audiworld Junior Member
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Mass air sensor codes are rarely a result of a failed mass air sensor. The code is triggered when the PCM sees the sensor reporting a value out of it's allowed "window" for any given rpm/ load.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.
Most often you'll see this (as well as the lean codes) with a vacuum leak. In some cars you can also see rich codes because the PCM's pushes fuel trims into the positives when it thinks it's running lean. It's trying to compensate for the lean condition but never does and the engine ends up running pig rich, all the while the PCM thinks it's running lean. The problem here is that now you run the risk of fouling your o2 sensors which means that even though you might fix the original problem, you're still not getting accurate readings. This is why for stuff like this, real time scanning of engine variables is priceless.
Whenever you get a code for lean/ rich, o2 sensor, MAF or MAP sensor you need to look at pretty much every component that controls the metering of air and fuel because DTC's rarely point to the component that is actually failing in these cases.
As for S4master, take his advice with a grain of salt. He's under the impression that he's the only one posting here with any kind of automobile knowledge and likes to follow up his poorly written posts with a picture that's not relevant to anything being discussed.
This is a message forum where a lot of people with varying degrees of experience come to discuss their cars. Some pull guesses out of their *** while others speak from years of experience. It is what it is. Just don't get caught up when someone's first bit of advice is to ignore everyone else.