Audi Fault Codes P0491 & P0492
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- Опубликовано: 24 авг 2021
- This is a common repair job that never seems to get any easier. The worst part of this job is removing the heat shields from the exhaust manifolds. Audi does offer a special tool kit that makes this repair possible without removing the manifolds. That tool part number is VAS6825. We will certainly be purchasing one for our shop. This is a costly repair due to the labor time involved. This repair is necessary to clean/de-carbon the air passage ports within the cylinder heads. These air passages are a part of the Emissions related Secondary Air system. If you own an Audi with this engine, budget for this repair if you have not already.
Thank you all for watching our video. Please feel free to post questions below.
UPDATE!
Here is a link to our new process for this repair
• Audi Fault Codes P0491...
This video is golden.
Thank you for watching our videos.
me before this video: I'll fix the audi
me after this video: TRADE IT IN!
Incredible video, thank you! It is very well done, easy to understand and thorough. Thanks again.
Great video! Very informative and clear. Pretty much answered every important question with your explanations. Saved me a lot of time and money. Much appreciated 🙏🏽
Thanks for taking the time to share. One thing I'll add is that with a restriction the blower current will decrease not increase.
Thank you very much for this super video . I am an électricien an I found this same problem with an Audi Q5 2010 . Code problem : P0491, P0492, P0116.
Hell of a job and video. Much appreciated!
Thank you for watching our video and for the kind words.
Thank you for this video. I have the same issue and this really helps me understand the amount of work involved.
Thank you for watching our videos and for the kind words.
Finally I understood this effing problem with my Q5.
Thank you sir for this video. You put it mildly as a "design flaw", I have a few unprintable words about it.
Very impressive! Thanks for sharing.
Just got P0491, 2013 S5 with 90K miles, APR stage II dual pulley. Google search led me here. Awesome video, I learned something new today. Thanks a bunch!
You are very welcome. Watch our P0491 update video. We are not using pressurized water to clean the passages. Thank you for watching our videos.
I never comment on videos, in fact my time is now. This is by far the best video available on this issue. Its been frustrating issue for me. I have it tore down this far already and will be doing this soon
Thanks for the best video out there regarding the P0491 0492 codes.
Thank you so much for the kind words. This is very motivating. We are so glad to help.
Great video!!! Thank you for taking the time to slow down and walk us through step by step.
Nice adapter on that 90 degree set up btw.
Stopped by due to 491 & 492 thinking it was aged out combi valves…thanks for complicating things. Lol
You are very welcome and thank you for watching our video.
This is the best video on this issue. Of course the pressure washer approach is faster but for me it was a good opportunity to renew all exhaust gaskets and nuts. For a shop it makes sense to purchase the pressure washer kit but for a DIY this is the way to go.
Thank you for the kind words and for watching our videos.
What is the link for the power washer kit?
Great video, I love the analogies and simple to understand explanation. I'm frustrated because I just spent $2000 on other repairs for it. It's old 2012 180k miles on it. I want it to lady for another year or so... It's been a great car but it's probably time to replace it.
Fortunately this fault codes does not reduce drivability. It is emission related only. Thank you for watching our videos.
This is an amazing video. Thank-you. Big job.
Thank you for watching! Here is our updated video on this job, with a much easier process
ruclips.net/video/w1VLf7Upkrs/видео.htmlsi=_UlmfY1nK5l6R0iD
Thank you for taking the time to produce this very informative video. It was very well done! I have a 2012 Q5 Audi with a 3.2 liter engine. It has 62K miles on it. Two weeks ago, the check engine light came on. The code associated with the light is P2432 "Secondary Air Injection System Air Flow/Pressure Bank 1 Sensor Circuit Low". There has been no degrading in engine performance. I spoke with the Audi advisor and was told that it is more than likely buildup of carbon in the secondary air injection system, which you cover in your video. The advisor told me that they have seen this occur in Audi's with as little as 30K miles. I did take it to my Porsche/Audi mechanic where the air pump was checked and found to be functioning correctly. They were not able to check the air sensor or other parts in the secondary air system due to glitches in their software program. I realize that you don't have vehicle in front of you but would like your opinion if you think the problem might be caused by carbon buildup in the secondary air system or a problem with a sensor/component in the secondary air system?
Thank you for your time
Hello and sorry for the delay. My guess would be that the air passages are restricted and this service is necessary to correct the issue. Thank you for watching our videos.
Amazing video, thank you for this
Thank you for great video, and very professional exclamation
Thank you for watching our video. Watch our update video for our newest process.
ruclips.net/video/w1VLf7Upkrs/видео.html
very nice mod. for the blower tube. every car do have some kind of carbon build up & also a way to clean up. good for another 100K.
Thank you! We have fun.
Brilliant explanation. 🥂🥂
thank you great video.i resolve the problem on my 2009 Q5 3.2.
Thanks for all the info, and thorough explanation (with visuals)! I agree, definitely not the best design for a “low emission cold start”. Only things I can think of to help prevent this, is to make sure you’re always using higher quality name-brand fuel, and of the highest octane rating recommend for the vehicle (91/93). That and/or every 25k miles, have a the engine carbon cleaned. Or maybe some solvent-based fuel additive cleaner every now and then?
Fantastic video, I have a 2010 Q5 just like in your video with 155k miles, and just got these codes during diagnosis. I am really bummed at the price to fix this. My mechanic says I need to take it to the dealer where they will use a high pressure water cleaning. Thanks for sharing - your explanation was great!
how much?
How much to fix it
At audi we use pressure washer and special nozzle ports with precise hoses
Yup, makes a huge mess....takes longer to clean up your bay after the procedure than the procedure itself. Horrible design.
Amazing!
I am literally going this as we speak!
Please view our latest video regarding this service. It is now uploaded to our channel as of yesterday and is titled Audi P0491 &P0492- Update. Check it out. It is a good one.
Thank you for watching our videos.
Very good video explaining whats involved, but I was just hoping to change out the pump in about an hour or so. Not slit my wrists for an entire weekend
This job is no fun even with all the tools. Thank you for watching our videos.
If there were a way to keep that pump running continuously, it would stop carbon from backing into those passages from the exhaust port. It would provide a constant positive pressure and this problem would not occur.
Woow such a nice video well explained, good mic and nice shots, thank you!
Thank you for watching our videos.
This information is very helpful. just wondering is there a recommended replacement parts list for doing this job? i know you talked about it but it would be great to know the full list of replacement items that should be bought prior to starting the job.
Great video, 14:23 what’s the process to get into the other side of the exhaust valve, to spray seafoam in the process of soaking the carbon? B6 30v
Great video. My 2009 68,000 mile RS6 C6 5.0L V10 has just started to throw up exactly the same 2 codes- does this also suffer the same issue and likely the same problem as in the vid? Also wondering if on my engine it’s an entire engine out job? 😔 Thank you
Very informative, thank you for sending. Do you know if the P0491 error is thrown, will the injection pump still try to push air through or is it bypassed? Is it possible to unplug the injection pump to "save it" while I'm waiting to schedule the bigger job. I don't know if my pump is good or if it is already failed. I am only getting the P0491 at this time, so I am assuming it is still functioning and passing air through Bank 2 for now. Are there any other uses for that injection pump or is only for pushing air through to improve cold start emissions?
Thanks for making this video, it is extremely helpful to understand the issue fully. I also watched the other 2 videos. 1 question: could you state the approximate hours required to complete this job?
I'm just curious, if it will help in anyway to PERIODICALLY spray some carbon cleaner into the secondary air intake pipe, so on few cold start cycles it sucks (or actually blows) into the passages and possibly clean them up some? I guess when the passage is already blocked - it won't help, but when they are not blocked yet - can it help?
Hello. I agree this sounds good in theory but I believe it to be impossible for the chemical to be evenly distributed to all parts of the passage way. I feel like this would be more work than benefit. Just my opinion. Thank you for watching our videos.
Very thorough, thanks for all the video and examples. I have a 2005.5 S4 with a 4.2L V8 @ 159k miles. Just got the P04092 code. Does the V8 have the same configuration and carbon issue?
Yes, the V8 does have the air passage through the cylinder head. Not the best idea but no one asked us. Thank you for watching our videos.
So what happen, other than the check engine light stays on, to the performance, i.e., how it runs? So once the pump burns out, does it prevent the vehicle from running? If the pump burns out, is that a definitive issue due to the carbon build up, or sometimes, is it just a failed pump at 120,000+ miles.
What is the cost for this cleaning process?
Can you clean carbon build up with sand blasting, but use dry ice or baking soda instead of sand? Great videos. I have a 2010 VW CC with the 2.0. You have shown me some cool tips. Thanks.
For this particular air passage, I do not see how blasting would be of any benefit. This stuff is so hard and the passage is so small. I have never tried blasting this but blasting does work on intake valves. Thank you for watching our videos.
On that particular motor, Audi should have a secondary direct injection system with a maintenance port that runs through the secondary air ports to clean those areas and the backside of the exhaust valves. A better way to clean those is to find a way to get sea foam, etc into the SAI pump, or lines and keep it running via VCDS, etc while injecting cleaner through the system. Kind of similar to sea foaming an intake manifold and intake valves through the port or hose near the throttle valve area.
Great video! Although seems like so much time, effort, and money spent to simply reduce emissions on cold starts.
Check out our "update" video for this repair. We now have the tooling to save us lots of time. Thank you for watching our videos.
Great video with thorough explanation of how involved this actually is. My 2010 S4 just started throwing this code as intermittent. I would love to take this on but it is something I unfortunately don't have the time to do. Anyone out there have an idea on how much this repair/cleaning would cost? Other than the check engine is there anything you really need to worry about? Again, thank you for the very informative and well done video.
I believe 1k
Thank you for watching our videos.
I just recorded this code on my 2010 S4. 100k mi. Damnit.
I heard this repair is about $3,000 - $4,500. Mostly labor because it's very time consuming
Just threw these two codes on my Audi, it’s an old 2003 2.7t allroad and it makes a strange noise on cold starts now. Is this the problem and how much is this going to cost to fix?
hank you for the video and explainer. By chance, can you post what he part number is for the bore plugs? At time stamp 2:55 you lift up a baggie with them and I think I'm reading 407-A090, but that doesn't seem correct (part numbers I've dealt with have always been longer) and I can't locate that part. Can you confirm what the part number is on those?
Hello, the part number is N0119078. Thank you for watching our video. We also have two additional videos regarding these fault codes and how we correct it. Continue to search our videos with P0491 & P0492
Would you be able to give a ballpark price estimate for fixing this issue on the 3.0
Excerent detailed explanation thank you. I can stop worrying and resetting the codes. Subscribed.
Question: when I do erase the codes I notice a difference in idle the second the code is erased even with the engine and oil at operating temp. Can you help me understand this?
Also if check engine light is on does that mean I'm running in "open loop" and or "limp mode"
This is an 05 all road 2.7T.
Thanks for your help.
Thank you for watching our video. When erasing engine fault codes, it is best to be in Key-on engine-off. Too many events are happening to be clearing fault codes with engine running. The mere presence of a check engine light does not mean the vehicle is in "open loop" nor "limp mode". Hope this helps.
@@premierautomotivediagnosti9432 thanks for the reply. this is important and I over looked the engine off part.
Thank you for very helpful video!!!💪
I have only P0491 on my 2012 A6 , i think i need both codes in order to get it fixed by the audi dealer, but not sure if i want them to fix and then cause more damages. My car has 118k miles and audi will fix issue free if is under 120k. Just service supercharger and control arms and car runs great.
Great video, thanks! I'm guessing I'm having the same issue; I have a 2010 Q5 premium plus quattro; how much did you charge for this job? So I know what to expect; thanks in advance
Hello. The price can vary per shop. Contact your local shop to provide the VIN number for the most accurate quote.
Thank you for watching our video.
I changed the air filter in my a8 and after a couple days I got a check engine light with these 2 codes. Can you please tell me if it is related? What can it be
Maybe you should let it run and put some sea foam at the intake of the secondary air pump when its not fully clogged yet, lets say every 50k miles or less. Should be easy because intake of the pump is at the air filter.
Thank you for the video. I was thinking I'd do this repair to clear the P0491 and 492 faults on my wife's car, at the same time I planned on doing the PCV valve. I'm thinking it may be less painful to just buy a new car. 2013 S4, and we love it, but with 160K on the clock I don't know these repairs are cost effective at dealer parts and shop rates.
We certainly understand. We just uploaded a video today showing the PCV replacement. Also check out our update video regarding the secondary air cleaning. We now use pressurized water. You can always ship your car to us and we can handle this repair for you. Thank you for watching our videos.
@@premierautomotivediagnosti9432 how much?
Great video. What happens if you don't get the carbon cleaning done and leave the codes and car as is? I have a 2010 Q5 3.2 V6 and the local mechanic who is an Audi enthusiast says, the codes will come back anyway after the 2K cleaning a week later....
If the carbon cleaning is done properly, those fault codes will not return. If the faults do return, the service was not performed properly or the issue was misdiagnosed. If you choose not to perform the service, the result is the check engine light will always be illuminated. Thank you for watching our videos.
Does it affect performance or fuel economy?@@premierautomotivediagnosti9432
Does this apply to 4.2l. I have same codes now
The ports go into the exhaust runner in the head, almost vertical. Those ports on the side of the head are blocked by the manifold and gasket itself
I’ll send you a video, I work at Audi, not saying what your showing is wrong but I’d just like to add to it, you make amazing videos
Hello, thank you for the kind words. Check out our update video showing how we now use the pressure wash method to perform this service. We also show borescope video of the passage ways.
Thank you for watching our videos.
Hello, thank you for the kind words. Check out our update video showing how we now use the pressure wash method to perform this service. We also show borescope video of the passage ways.
Thank you for watching our videos.
I just recently bought a Audi Q5 2010 with these codes on it and the dealership promises me they would get rid of the before I take it home.
They are replacing the combination valves and I’m worried that they may get away with a temporary fix when they don’t want to do this full job.
Do you think by replacing the combo valves it will be a temporary fix turn off the MIL and pass the readiness check ?
Hello and thank you for watching our videos. Replacing the combi valves will not resolve the carbon issue. The readiness monitor will immediately fail even after installing new combi valves. There is no way to "fix" this issue other than cleaning the air passage ways within the cylinder head.
Could i just take the egr valves off and clean them from the back side with a flex hose?
You can certainly clean the main distribution tube from either end. The problem is the smaller passages that run perpendicular to the back side of the exhaust valve. These are impossible to gain access to and clean without removing the exhaust manifold.
My God how much do you charge to do this repair if you don’t mind me asking? I’m near Tennessee
The most recent repair of this kind was right at $2600 parts and labor. That price also included replacing the secondary air pump. We do have out of state clients and would welcome your business as well. As you can see, we are very transparent with our work. Thank you for watching our videos. Feel free to call or email our shop at anytime. WWW.PADiagnostics.com
What if there is only P0492 code? Is there hope that it is not the carbon but something else? 3.0T A6 (2015)
Did you see the TSB for these codes? There’s a special adapter and tools used for this issue. The service info shows that you don’t even need to remove the whole front end.
Besides that, great video and very informative. I like that you showed the borescope video for the issue.
See the link to our new video. This is how we perform this service now.
ruclips.net/video/w1VLf7Upkrs/видео.html
Just a question, how hard it is to disassemble the front end ? Remove the Radiators ?
Removal of the front end is not that difficult, but you need to have someone evacuate the a/c system leagally. Other than that there are plenty of videos on how to take front apart on RUclips.
got both of these error codes and a cylinder 1 and 5 misfire. any idea what could be happening? carbon buildup or vacuum leak? (no hissing sound though)
I don't think the misfires are related to the P0491 and P0492. I really don't see how a clogged SAI could induce misfires. For the P0491 and P0492 codes, first check that the SAI pump is running at startup. You can also check if the combi valves are operating properly. If everything is fine, then you likely have a carbon build up issue. There is a TSB on this issue. For the misfire, do the usual diagnostic procedure. Change spark plugs if they have not been replaced recently. Swap coils to see if the problem follow the coil position. Test compression... Could also be an injector issue. You can check for fuel rail pressure drop after you shut off the engine. There is plenty of information available on how to diagnose misfires. Good luck!
We agree with David G. The misfires and the secondary air fault codes are not related. Your vehicle has a separate issue regarding the misfires. I would suggest correcting the misfires first as they are more important to resolve. Thank you for watching our videos.
How much will it cost that cind of job?
How can I find those parts on eBay?
Is it valid for A3 1.6 MPI 2009 ?
I've got the same issue, I think.
We have only seen this issue on the six cylinder engines.
Crazy amount of labor all coming from the manufacturer's design.
How many hours did you bill them?
Stay safe
We have been billing 10 hours for the repair plus any diagnostic time. In my opinion, the worst part is removing the heat shield from the driver side exhaust manifold.
Also, cant you just rig up a pipe that bolts onto the COMBI valve where you can just blast seafoam down it while the engine is running ?
When the passage ways get to this point, no chemical I know of can clean out this much carbon. Thank you for watching our videos.
I got a 99k KM 2013 Audi S4 and this issue popped up.
Now I'm torn on whether I should pay a few thousand dollars to get this fixed
We would be more than happy to help you with your Audi. Audi/VW is our specialty.
We do have out of state clients if you are not in the North Georgia area. Call us or email us anytime. Thank you for watching our videos.
WWW. PADiagnostics.com
Where are you located and how much do you charge for this service?
Audi warranty didn’t cover mines at 105-thousand miles and CarShield didn’t either total I paid was $3-thousand A7..😤😤 I’m going with Lexus next year.
What happened if you put a new air pump and don’t turn on the air pump
Thanks for the great video! Any idea how many hours to do this? Also I'm getting P0492 only any chance it could be something simpler since P0491 isn't showing up? 2015 Q5 3.0 150k miles
Hello, the amount of hours to clean the passage ways using this procedure can range from 10-20 hours depending on experience and tools/lift available. I personally will not perform cleaning this way again. It is truly frustrating. If you have seen our update videos with these fault codes we now use pressurized water to clean the passage ways without removing the exhaust manifolds. Using the pressurized water is far more efficient but does require a special tool set which I have only found available from Audi. Although you are only getting the fault code for one side, we can assure you that the culprit is the air passage ways stopped up with carbon.
Thank you for watching our videos.
@@premierautomotivediagnosti9432 thanks for your response! The check engine light was on for 3 days and ~700 miles and it went off today.. Hooray it's better! :D
How much is cost for this repair
My Audi S5 had code P004900. It came up as “Code P004900 turbo over speed. Found control solenoids filled with coolant from internally leaking water pump, needs water pump and complete vacuum system with solenoids”
Why is this code only 1 number away, but such a different problem lol?
do i need to remove exhaust manifold or raise it up so i could use a drill bit?
The manifold must be completely unbolted from the cylinder head and catalyst. It can then be moved back or removed completely. Honestly, it is easier in the long run to completely remove the manifolds. Check out our Update video regarding these same fault codes. Thank you watching. We hope this helps.
How much does a job like this cost?
Very good video, not what I wanted to hear but I can only hope the customer doesn’t want to fix it. Can’t believe Mitchell diag online has NOTHING pertaining to a p0491 on a 15 q5.
The secondary air pumps are also very expensive. Thank you for watching our videos.
Have the same issue on a Volkswagen Tiguan 2022
did you remove the combi valves to cleanup all the way back?
No, the combi valves do not have to be removed. I recommend keeping them in place. Removing them is not necessary. Thank you for watching our videos.
I am receiving these codes and found that it is blowing the 40A fuse near the ECU (2007 Audi S4). I replaced the fuse, the code went away for a time and came back about 2 weeks later... blew the fuse again. I will be checking the pump next but wanted to mention this in the event you may have some further advise.
Hello and thank you for watching our video. The pump is likely the failure item but these pumps are very expensive so you don't want to guess at it. Also check the vacuum hose that run from the secondary air solenoid valve to the combi- valves. One solenoid control the vacuum to both combination valves. This rubber vacuum hose "T's" and runs to each combi valve. Verify this hose is not broken/disconnected. The best way to test the pump is to apply voltage and ground directly to the pump and see if it will operate. If this car is blowing fuses, I suspect a faulty pump also.
That is probably a wire problem, the brown and red one to the pump, broken insulation.
I have heard about decarbonozation process that injects hydrogen into the air system of the car and that way it cleans it up maybe that could be a way to prevent this, ill do it soon if i get good results ill comment back. 👌
Please do. We have found nothing yet to prevent this issue. Always looking for a new process.
Did this work?
How much is the cost of this repair ?
COULD YOU SHARE THE PART NUMBER OF THOSE FREEZ PLUGS IS YOU DON'T MIND
Hello, the part number is N 011 907 8 Audi calls it an "end cap". Thank you for watching our video.
How much does a job like this cost? Not sure if I missed it if it was said
It can vary so much. Request a quoted from your local repair facility. Thank you for watching our videos.
How much will this set me back ☹
Great video! Thank you. I own a 2017 SQ5 and have the same codes. I am not a mechanic, but have done plenty of wrench turning in my life and am considering doing the job myself. Any chance you can share the parts list for this job?
@TD K not under warranty… I’m being charged for this to be done, and what’s worst is the codes came up two days after the dealer replaced the water pump and PCV valve.
@@pwrgolfpr That's funny, I just got finished replacing my water pump, thermostat, and pcv valve last week and now mine just kicked out this 492 code.
I just replaced my water pump also a month ago and got this code now as well. No 491 code just 492
I also got the code two weeks after replacing pcv, water pump and thermostat.
I just had the thermostat and hoses replaced. Picked the car up and when I started the car, the check engine light was on and these codes were the issue. Has anyone found a connection from repairs to coolant system and suddenly having the codes appear?
Just code SAI pump off completely. No need to remove any parts. Can't do with VCDS but many people has equipment for that.
I dont think that will solve anything when trying to get it to pass emissions. the o2 sensors at the Cat convertor will pick up the lack of air flow and keep the check engine light on. unless i am missing something.
Quick question: P0491 is driver's or passenger side?
P0491 is a fault on bank #1 or passenger side.
My 2015 S5 has this issue at 62K miles.
*You didn't mention my engine but it is a V6 in my Audi Allroad Quattro 2.7T and I'm getting both of those codes. I'm at about 168000 miles now. Can you give me a ballpark price wise so I can compare to what my shop says. Thanks for your time.*
If you have these codes for the 2.7L V6, this is not the issue. Those systems were designed differently and will require a proper diagnosis to determine the actual failure. Thank you for watching our videos.
How many miles before it start happen my car is 50k and engine light already on and I took to advance auto parts to checked it show
P2442 Secondary Air In jection System Switching Valve Stuck Open Bank 2 is that what it is? I have Q5
Without seeing your vehicle in person, I would suggest that you have a different issue that what is in this video. I would suggest getting a proper diagnosis for that fault code prior to committing to any repair. Thank you for watching our videos.
@@premierautomotivediagnosti9432
thanks
@@changinghumanityaiwithhear3858 Were you able to resolve the issue? If so, what was the problem, and how did you resolve it? I'm experiencing the same P2442. Thanks!
You can delay this issue by continuing to use premium fuel.
With these codes with it pass smog test for registration?
With these fault codes present, the vehicle will not pass an emissions test.
Wow. Time.
Reminds of my nightmare 10' Q5. The amount of cursing I did when I owned that turd. Last repair was the ECU frying because the geniuses at VW decided to put the ECU exactly where the window water runs and drains to the ground. Stupid af
If the car runs fine I’d 100% just unplug the pumps and leave it alone and live with the light. I have a 2006 cayenne turbo and mine keeps stalling while I’m idling. Unfortunately I have no choice but to fix it.
How the hell did u get heat shields off I got big hand not fun
Funny you mention that. This entire job is difficult but those heat shields are the worst part of it all !!! Thank you for watching our video.
So can you drive with those fault codes on?
Yes but you won’t pass smog check
@kaylahgrisby2886 I erased them and they haven't appeared again
Can you just spay a shit tin of carbi cleaner with compressed air down the COMBI valve ?
I wish we could. This stuff has to be mechanically removed. I did try the chemical way in the past and just wasted my time. Thank you for watching our videos.