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gomi_otaku, Technician
Category: Audi
Satisfied Customers: 3449
Experience:  VW certified technician, Chicago VW/Audi Training Center, Seattle VW/Audi Academy
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2010 audi q5 3.2 replaced driver side head due to broken

Customer Question

2010 audi q5 3.2 replaced driver side head due to broken tensioner....the used head that I installed does not have the port to connect the secondary air system so now car throws code P0492 insufficient flow bank runs fine and no other codes are
coming up.what sets the code?can I put a whole in the exhaust manifold and connect to it...would that keep it from.setting the code again???
Submitted: 1 year ago.
Category: Audi
Expert:  Eric replied 1 year ago.


You need to install the correct head in order to resolve this.

Customer: replied 1 year ago.
But what exactly detects the flow...the engine runs perfect,this is the only code,couldn't be rerouted?
Customer: replied 1 year ago.
Thank you for your effort but nobody replied as you see,I think it's fair that I get a refund
Expert:  gomi_otaku replied 1 year ago.

The secondary air system is more complex than you first imagine. If you simply put a port into the exhaust, you would get exhaust pressure feeding to the secondary air pump all the time, destroying it. The normal system has a solenoid valve that can open to allow the secondary air flow through. I would contact the place you got the head and tell them they sent wrong part, as it can't be easily modified. It's not your fault, it is the vendor.

Customer: replied 1 year ago.
I ASKED WHAT EXACTLY detects the insufficient flow not about how complex the system is and by the way is not that complex,few hoses, few valves sensors and a air pump,
Expert:  gomi_otaku replied 1 year ago.

OK, that was ONE of your questions- you asked about re-routing the secondary air flow straight into the exhaust.

The O2 sensors determine the flow, based on the amount of oxygen in the exhaust (because, by design, oxygen is the ONLY thing they detect, they do not analyze your exhaust, just the oxygen balance, to determine combustion efficiency, etc)

Customer: replied 1 year ago.
Thank you sir
Expert:  gomi_otaku replied 1 year ago.

hopefully you can get this resolved

Customer: replied 1 year ago.
Was thinking to make a metal line that would have a one way check valve on it from the combi valve to the exhaust manifold that way there is flow and with a valve installed the exhaust won't go back in the secondary air system....
Expert:  gomi_otaku replied 1 year ago.

OK- I hope you are up to fabricating this- remember, the system has to be able to sustain exhaust temperatures and function thousands of times (optimally) Let me know how it goes.

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