Secondary air injection system codes and related.

[MikeB8.5]

So I've run into what seems to be a clogged secondary air system on my 13 S4. It throws the code P0491 bank 1 and 2. Will the a stuffy secondary system cause a weird idle?

I've recently done some DIY maintenance to try and troubleshoot my idle issue ei. new PCV and carbon cleaning on the intake side as I've heard both will relate to unusual idle. After all that it still idles strange. It will kind of dip low and come back up combined with changing the exhaust tone much deeper on idle. I've also seen a code for "idle higher than normal" I can't remember the actual code though since I haven't seen that one reappear yet.

Are there any tunes that bypass the secondary air system or is it possible to bypass it? All I know of it's function is that it injects clean air into the exhaust to help burn off harmful emissions before passing through the catalytic converter.

Thanks,
Mike

[VinnysS4]

Personally it sounds like a vacuum leak in the secondary air injection system. That would make your idle higher and the computer would end up pulling back trying to lower the idle
What are your fuel trims sitting at?
Sent from my SM-N920V using Tapatalk

[Vendetta44]

U know there is a warranty extension of 10yr/120kmiles for secondary air injection through Audi for the 3.0T motors. If setting both banks your golden. Take it in. They will do a port cleaning

Sent from my SM-N960U using Tapatalk

[Whitee]

I’ve had a P2432 for some time now and been looking for help on the forums and it doesn’t seem anyone has EVER had this code. Picked up a SAI Pressure Sensor tonight. From what I’ve heard your code related to carbon buildup as others have mentioned.


Sent from my iPhone using Tapatalk

[MikeB8.5]

Personally it sounds like a vacuum leak in the secondary air injection system. That would make your idle higher and the computer would end up pulling back trying to lower the idle
What are your fuel trims sitting at?
Sent from my SM-N920V using Tapatalk


U know there is a warranty extension of 10yr/120kmiles for secondary air injection through Audi for the 3.0T motors. If setting both banks your golden. Take it in. They will do a port cleaning

Sent from my SM-N960U using Tapatalk


I’ve had a P2432 for some time now and been looking for help on the forums and it doesn’t seem anyone has EVER had this code. Picked up a SAI Pressure Sensor tonight. From what I’ve heard your code related to carbon buildup as others have mentioned.


Sent from my iPhone using Tapatalk

It's intermittent tho when the it idle hunts. If it were a vac leak wouldn't it be constantly doing it? How do I check my fuel trims? I need VAGcomm for that I assume?


I spoke to a tech at Audi and gave him my vin to run, he came back with saying there were no existing warranty extensions on the SAI system or my timing chains for that matter. Would the extensions only be issued to the USA? I'm in Canada.


I could give the SAI sensor a shot but I doubt that's the issue. For sure without a doubt it's carbon build up in the SAI system.


The tech I spoke to said Audi recommends cleaning the SAI with a pressure washer... no joke. Instead of pulling the entire motor.

[Vendetta44]

Shoot me your vin. I'm a Service writer for Audi of grand Rapids in grand Rapids Michigan. I can look it up tomorrow for you. Should still be valid even if your in Canada
It's intermittent tho when the it idle hunts. If it were a vac leak wouldn't it be constantly doing it? How do I check my fuel trims? I need VAGcomm for that I assume?


I spoke to a tech at Audi and gave him my vin to run, he came back with saying there were no existing warranty extensions on the SAI system or my timing chains for that matter. Would the extensions only be issued to the USA? I'm in Canada.


I could give the SAI sensor a shot but I doubt that's the issue. For sure without a doubt it's carbon build up in the SAI system.


The tech I spoke to said Audi recommends cleaning the SAI with a pressure washer... no joke. Instead of pulling the entire motor.

Sent from my SM-N960U using Tapatalk

[cspcrx]

I just had this. Yesterday morning started the car it had an odd stumble during warm up, just for a brief moment. CEL came on and stayed on. Started the car to leave work did it again, same brief stumble and CEL light. Ran codes on it last night and had P0491 & P0492. I have the letter Audi sent on this being covered until 120K or 10 years hope they don't play the TD1 card on this. I saved the code pull but am sure it will come on again. Have to call the dealer and see what they say, will report back OP please do so as well.

[Whitee]

I just had this. Yesterday morning started the car it had an odd stumble during warm up, just for a brief moment. CEL came on and stayed on. Started the car to leave work did it again, same brief stumble and CEL light. Ran codes on it last night and had P0491 & P0492. I have the letter Audi sent on this being covered until 120K or 10 years hope they don't play the TD1 card on this. I saved the code pull but am sure it will come on again. Have to call the dealer and see what they say, will report back OP please do so as well.

I’d imagine it needs to still be throwing those codes as permanent to be fixed. Not intermittent..or cleared.


Sent from my iPhone using Tapatalk

[cspcrx]

I will wait for it to come up again and leave it up. I saved the codes prior to clearing them so I have a full detailed report. Going to call my service guy to see what he thinks Monday. It did not come on today.

[rj124104]

Be careful with the warranty. They're reluctant to admit it. I took mine to the dealer and got a complete load of BS and a $170 diagnostic fee. They didn't respond to my email.

[Vendetta44]

I just had this. Yesterday morning started the car it had an odd stumble during warm up, just for a brief moment. CEL came on and stayed on. Started the car to leave work did it again, same brief stumble and CEL light. Ran codes on it last night and had P0491 & P0492. I have the letter Audi sent on this being covered until 120K or 10 years hope they don't play the TD1 card on this. I saved the code pull but am sure it will come on again. Have to call the dealer and see what they say, will report back OP please do so as well.Would recommend being flashed back to stock before hand. They can flag it if tuned and refuse to not do the port cleaning. If both codes are present and your within the coverage years and mileage then your covered but I would just feel the dealership out but usually a tuned s4 doesn't need a port cleaning Haha atleast I've never seen one at my dealership

Sent from my SM-N960U using Tapatalk

[cspcrx]

My car has been tuned for 40K so in my case wont matter. But for you if your worried it cant hurt and will help to possibly eliminate arguments. That being said based on the past they could deny you just for an intake and exhaust. Some of that is really up to the dealership.

[cspcrx]

Dealer called and said they see it as part of the power train warranty and since I am tuned and flagged as TD1 it would be declined. See what they want to do it and what some independent shops want.

[MikeB8.5]

I haven't had time to follow up with my dealer on this issue. I was notified and given the vehicle data print out of the extended warranty coverage (thanks to Vendetta44) for my issue and when I spoke to my service advisor over the phone, they wanted me to bring the car in for diagnosing. All I wanted was for them to confirm my warranty extension over the phone but they refused to do so and insisted I bring the car in first. Didn't really feel like paying the labor for them to plug the car in and tell me what I already know so I parked the car for the upcoming winter here in Canada and I'll deal with them in the spring when I can drive it again.

I'm currently at 150k on my car which I purchased second hand and have no idea if it has a tune on it or not, so fingers crossed I don't get flagged if it does.

If anyone else is going through this please post up and keep me updated how things go.

[cspcrx]

I got a call from them this morning a hose for the system on the passenger side of the car somehow disconnected. It is after the pump so it was blowing air into the engine compartment. They reconnected it and cleared the codes all is good! Thank God. I was looking at $1500 for a cleaning.

I had not been in there doing anything and the last time the car was touched was 4 months ago so who the heck knows how that happened. Just glad it was a lot less $! Going to have them show me where so I can keep an eye on it if I get the codes again.

[IntheQ7]

Shoot me your vin. I'm a Service writer for Audi of grand Rapids in grand Rapids Michigan. I can look it up tomorrow for you. Should still be valid even if your in Canada

Sent from my SM-N960U using Tapatalk

Hello I'm new to the post and I came across your statement. Having problems with getting this service done. Throwing both codes after a check engine light. Car has no power when pressing the accelerator at times. Wondering if I can send my VIN over and you can help me find out how to get the situation corrected. Thanks

[Vendetta44]

Hello I'm new to the post and I came across your statement. Having problems with getting this service done. Throwing both codes after a check engine light. Car has no power when pressing the accelerator at times. Wondering if I can send my VIN over and you can help me find out how to get the situation corrected. ThanksHow many miles do you have on your Q7? Send me the vin and I will let you know if the warranty extension is valid on your car

Sent from my SM-N960U using Tapatalk

[IntheQ7]

It has 85372. VIN is WA1LGAFE7FD006790

Sent from my SM-G955U using Audizine mobile app (http://r.tapatalk.com/byo?rid=87676)

[IntheQ7]

Vendetta44 anything come back in your search? AoA told me I'm not covered even though my 2015 has the same 3.0 TFSI Engine in those that were named in the letter.

Sent from my SM-G955U using Audizine mobile app (http://r.tapatalk.com/byo?rid=87676)