P0491 and P0492
12-11-2014, 11:49 AM
#11
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Thank you for the complete scan.
As you'll see it's an amazing tool and provides a mountain of information.
It's a bit of an old scan, and typically we recommend you clear all DTCs (codes) drive the vehicle and see what returns.
Here's my quick and dirty analysis:
Interestingly I don't see any of the SAI codes you are asking about.
Suggest fixing any obvious issues, clearing existing DTCs, drive the vehicle a few times, and post a new scan.
As MP said, P codes from generic code readers are of little value on a vehicle this complex.
You will need to use VCDS to run output tests in some cases as well.
As you'll see it's an amazing tool and provides a mountain of information.
It's a bit of an old scan, and typically we recommend you clear all DTCs (codes) drive the vehicle and see what returns.
Here's my quick and dirty analysis:
- ignore N145
- G201 is concerning, but may go away once cleared
- ignore key issue with Kessy, probably battery related
- G65 might be an issue, check after clearing
- M3 is probably a blown bulb
- you CD changer is from another vehicle and I suspect your audio is cutting out every 2 seconds - only Audi can remove CP
- we already know about level control issues
- driver seat has some electrical problems, bad switch or wiring
- intermittent voltage problem with sunroof - could be wiring
- alarm horn may need replacing
- a boatload of bulb errors - could be burned out or wiring
- ABS is complaining due to sensor
- you need new brake pads in the rear
- IF amp may have corroded connections
- system shut things down to protect the battery - Quiescent mode [see my post on locking the vehicle when not in use]
- ignore or disconnect telematics - that's OnStar
- wiring issue for parking sensor - corrosion or break likely
Interestingly I don't see any of the SAI codes you are asking about.
Suggest fixing any obvious issues, clearing existing DTCs, drive the vehicle a few times, and post a new scan.
As MP said, P codes from generic code readers are of little value on a vehicle this complex.
You will need to use VCDS to run output tests in some cases as well.
Thanks so much for comments and suggestions.
This scan was done October 26, 2014 I believe.
Is that old ?
At that scan 'Charlie' did an Autoscan and then 'cleared'.
I am going to get him to do it again this weeekend.
In meantime I will work through.
Some issues are very old, I just lived with them.
Others could not be ignored.
The many lighting issues I can work through.
The next big issue is for we to get it to pass an e-test--in Canada thats an emmissions type test.
0491/0492 will fail it for sure as they are triggering the check engine.
thanks again
12-11-2014, 11:54 AM
#12
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Thanks so much for comments and suggestions.
This scan was done October 26, 2014 I believe.
Is that old ?
At that scan 'Charlie' did an Autoscan and then 'cleared'.
I am going to get him to do it again this weeekend.
In meantime I will work through.
Some issues are very old, I just lived with them.
Others could not be ignored.
The many lighting issues I can work through.
The next big issue is for we to get it to pass an e-test--in Canada thats an emmissions type test.
0491/0492 will fail it for sure as they are triggering the check engine.
thanks again
This scan was done October 26, 2014 I believe.
Is that old ?
At that scan 'Charlie' did an Autoscan and then 'cleared'.
I am going to get him to do it again this weeekend.
In meantime I will work through.
Some issues are very old, I just lived with them.
Others could not be ignored.
The many lighting issues I can work through.
The next big issue is for we to get it to pass an e-test--in Canada thats an emmissions type test.
0491/0492 will fail it for sure as they are triggering the check engine.
thanks again
all brakes were done about 18 months ago but I think the guy, a volks mech, didnt go through proper steps ???
I noticed a leak in exhaust right in middle of car. looked under and saw a crack in exhaust right where the "octopus" is--you know it's shaped like an X under there--so right where everything intersects in the middle. It looks like a significant crack or hole.
could this be the issue ?
12-11-2014, 12:07 PM
#13
AudiWorld Super User
Older than immediately after the codes show up is too old 
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Yep. Similar in the States, varies by area.
No doubt.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
Possibly - a lot of guys "wing it" and don't use the proper procedures.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
It's an issue, possibly will cause other codes.
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
I noticed a leak in exhaust right in middle of car. looked under and saw a crack in exhaust right where the "octopus" is--you know it's shaped like an X under there--so right where everything intersects in the middle. It looks like a significant crack or hole.
could this be the issue ?
could this be the issue ?
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
Last edited by jakematic; 12-11-2014 at 12:09 PM. Reason: post script
12-12-2014, 05:50 AM
#14
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Older than immediately after the codes show up is too old
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Yep. Similar in the States, varies by area.
No doubt.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
Possibly - a lot of guys "wing it" and don't use the proper procedures.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
It's an issue, possibly will cause other codes.
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Yep. Similar in the States, varies by area.
No doubt.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
Possibly - a lot of guys "wing it" and don't use the proper procedures.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
It's an issue, possibly will cause other codes.
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
NO, nothing is blinking.
12-12-2014, 05:54 AM
#15
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Older than immediately after the codes show up is too old
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Yep. Similar in the States, varies by area.
No doubt.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
Possibly - a lot of guys "wing it" and don't use the proper procedures.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
It's an issue, possibly will cause other codes.
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
Good plan.
Long term you may want to invest in a genuine VCDS cable, but I understand you have lots of other things to worry about right now.
Yep. Similar in the States, varies by area.
No doubt.
Even if you cleared them, the readiness bits are not all zeros on the engine so it would fail anyway.
Possibly - a lot of guys "wing it" and don't use the proper procedures.
As I recall there is a step where you measure the pad thickness and input via VCDS.
That procedure may have to be redone.
It's an issue, possibly will cause other codes.
Secondary air injection is typically cracked plastic or a bad SAI pump.
Again there are tests in VCDS you can run for that.
Is your 'CEL' (what Audi calls a MIL for Malfunction Indicator) blinking at all?
If so, that can point to injection problems.
This link will help: Audi A8/S8 (4E) - Ross-Tech Wiki
Read through it for every module.
Post up complete new Auto-Scan once you get it done and we'll take it from there.
ps- Tons of good info here, all free Audi Portal: Diagnostic
I recall watch a proper 'how to' video on youtube.
I recall needing to do something with the battery and the emergency parking brake, in the process.
I'm almost certain some technical step was missed.
Car seems to be braking fine and manual inspection of what pad I can see and touch, appear as normal.
Ya so next is I will get the scan done, cleared, then re-scan and save that file.
12-12-2014, 06:39 AM
#16
AudiWorld Super User
Good. One less thing to worry about.
It's a very specific procedure that is too often "bulled" through using 1970s methods.
No doubt a recalibration will fix it if the pads are good.
No doubt a recalibration will fix it if the pads are good.
12-16-2014, 09:43 AM
#17
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Good. One less thing to worry about.
It's a very specific procedure that is too often "bulled" through using 1970s methods.
No doubt a recalibration will fix it if the pads are good.
It's a very specific procedure that is too often "bulled" through using 1970s methods.
No doubt a recalibration will fix it if the pads are good.
off to do some reading now....
12-16-2014, 09:52 AM
#18
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12-16-2014, 02:28 PM
#19
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I will go check.
your display is a little dif than mine.
back in 10 mins.
but I do think its the SAP as it sounded like a high pitched moose call when I started car. it lasted for about 10 seconds and then all ran well. I say moose call cus it kind of sounded guttural then deep then up again and then down. Then it stopped.
So does seemed related to 'cold start' issue. Car was parked indoors and was about 5celcius at the time or like 18 farenheight. just thought I'd mention.
going to go read display now
your display is a little dif than mine.
back in 10 mins.
but I do think its the SAP as it sounded like a high pitched moose call when I started car. it lasted for about 10 seconds and then all ran well. I say moose call cus it kind of sounded guttural then deep then up again and then down. Then it stopped.
So does seemed related to 'cold start' issue. Car was parked indoors and was about 5celcius at the time or like 18 farenheight. just thought I'd mention.
going to go read display now
12-16-2014, 02:36 PM
#20
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No they are not illuminated like that.
wondering if I did something wrong to air filter when I took it out to clean and recondition, and put it back in incorrectly.
I had 0701 before 0491/92 so cleaned MAF sensor-----and 0701 went away. that was about 6 months ago.
now 0701 is back plus the 0491/92
will have to read some more tomorrow.
wondering if I did something wrong to air filter when I took it out to clean and recondition, and put it back in incorrectly.
I had 0701 before 0491/92 so cleaned MAF sensor-----and 0701 went away. that was about 6 months ago.
now 0701 is back plus the 0491/92
will have to read some more tomorrow.