I got this code on Sunday morning before taking off on a long trip to see my parents. Everything runs great and sounds fine so I went ahead and drove it. If anything is different maybe power is down every so very slightly but I can't even tell if it's down. What's weird is my gas mileage is showing as mightily improved since the code came on. I had a good easy interstate drive yesterday where I didn't really have to hit the brakes any but I clocked an impressive 31 mpg which is the best I've ever clocked by far, previous best was about 25 or 26 mpg.. any thoughts on that?

The auto zone computer suggests "Reinstall Vacuum Hose at Intake Manifold or Fuel Pressure Regulator" is the most likely fix. So just wondering how urgent this is I'm supposed to see my mechanic soon to do routine maintenance, can I keep driving it since it seems to be all normal except with improved fuel economy? I've actually driven almost 500 miles (almost all interstate) already in the 2 days since it happened and no issues so I'm guessing I can do another 100 or so until I see him.. or would this be easy enough to just inspect and pop the hose back in? I used to do that on my old BMW X3 the hose running into the air filter housing came lose a time or two and it was easy enough to pop back in, however I did pop the hood and checked everything I could see and nothing appeared disconnected..

last thing is my mechanic told me I have a main seal leak.. doesn't seem like it would be related but could it be?

 

Just found a couple videos from this guy on Youtube apparently it's not simple at all...

Original video
He buys a special tool from VW which does it faster in this update video
Anyone trying to buy a 2015 Q5 3.0T with 150k miles? Gray,

 

Pass thanks.

Your ECU is adjusting the AFR to compensate for the vacuum leak. You can keep driving but always better to fix sooner. Harder to sell or trade in with an active check engine light.

Rear main seal leak has nothing to do with this issue

 

P0491 & P0492 Secondary Air Injection System Insufficient Flow - AudiWorld Forums

A P0492 DTC code is a fault in the Secondary Air Injection system, it has nothing to-do with any kind of vacuum leak, or a vacuum leak caused by a faulty rear main crankshaft seal.

A vacuum leak typically will set a "Lean Condition at Idle", or "Excessive Idle Air" DTC code.

 

I don't know much about this model...but a leaking RMS on any modern engine can cause a vacuum leak. So why do you think it has nothing to do with it?

 

Modern engine or just over engineered German engine?

I guess I could be wrong. Did some digging and it seems on these Audi engines a bad PCV could cause the rear main seal leak. Or the rear main seal leak could trigger a code because the vacuum in the crankcase.

Either way it's a pain in the ***. https://www.shopdap.com/blog/post/re...i-engines.html

Every day I'm thankful I don't have a car with the Audi/VW 2.0T engine. What a lump of garbage.

 

On any engine for the last 20+ years (actually way longer, since the 60s I believe but I wasn't around then). Do you understand what crankcase vacuum is?

Do you know this post isn't about a 2.0T? Pretty much everything you wrote in this thread makes absolutely no sense.

 

Don't insult me. I admitted I could be wrong.

 

I am not insulting you at all. If you understand what crankcase vacuum is you should understand this has nothing to do with a 2.0T (the OP has a 3.0T), an Audi, or an "over engineered German engine". You can have this exact problem on literally just about every car on the road.

Calling the 2.0T a lump of garbage has nothing to do with this. I am genuinely confused by several of your comments.

 

Agree on all points.