Resoom

I've a 2010 Q5 with the 3.2 and the CEL has been coming on - VAGCOM indicates P0491 and P0492 - insufficient air flow secondary banks. Have started to check the system and my first point is the pump. I've disconnected it and fed it directly with 12 V and it just buzzes with no air. I've tested it using a DC power supply rated at 6 amps max and am just wondering if its enough power as the air injection system fuse is 40amp. I can touch the top of the impellor inside the pump and can rotate it slowly - feels really stiff. My question is, is the pump toast or am I just testing it with an insufficient power source to get it to rotate and any recommendations as to where to source the pump? it's looking like an expensive part (in Canada), thanks!

rdA4WtQ5

The codes you have are indicative of the carbon blockage of your secondary air ports. Covered by extended warranty in the USA. They used to remove your engine to fix but they have an easier way now.
Contact your Canada dealer to find out if you are covered and report back.

Resoom

I have my appointment booked with the dealer next wk - just want to ensure they SAI system is working properly prior to taking it in. The carbon removal is covered by the extended warranty but the other elements within that system are not, hence my checking the pump, relays, fuse and combi valves. I can fix/repair/replace that myself. just don't want to be in the position of the dealer having it half taken apart and then receiving a phone call requiring replacement of all or some of the components I can check myself.

MP4.2+6.0

Sounds to me like your pump may be no good. When I tested (one of) mine on a 2006 A8 W12, I took a simple piece of like 16 gauge wire and hooked one end to a battery charger lead. Charger was only set to 15A. In my case pump impeller area had filled w/ water and it didn't spin at all. The W12 has two pumps and other one spun fine so I knew my procedure was okay. Pump replaced, no more issue. And no, no huge arcs like you would see at high amperage; the standard little flicker as you made the connection. With two pumps in mine, I can see why overall system might be amp rated somewhat higher, though even so these are fairly compact motors as things go.

The pump should put out discernible air flow too. Yes, things can be clogged further downstream like air injection ports (3.2 being unfortunately like ground zero apparently for issues here). But if pump output isn't there to start--when you have the hoses off both suck and pressure sides--expect that is its own issue w/ pump. BTW, on my W12 the OE for pump was Pierburg. In turn you can buy Pierburg pumps from various indy parts places (even Amazon IIRC) for less than the on line dealers.

Resoom

Thanks for your responses. Just a quick update. The power supply I used to test the pump which was 12v had insufficient amperage to turn it, hence it just buzzed. I tested it with the battery terminals So works fine. Looking like the SAI system works as it should which is pointing toward the carbon issue with the secondary exhaust ports. Have an appt with dealer next wk to see what's what. I've read they no longer pull the engine but use a diff method. Anyone know what is involved in the new method to remove carbon?

Fixxxer0808

I have a code saying I have insufficient flow at bank 1, but I'm not getting power to the pump. The fuse is good, is this controlled by a normal relay or a module, and where is this puppy?

Ken Ramoutar

Can anyone tell me where exactly this pump is located. I cant see it from the top of the engine. I dont hear it running on cold starts and have the dreaded po491 and po492 codes. I could be the carbon build up issue but want to make sure its not the pump first.

sonofsql

It is at the front right of engine bay, near bottom of radiator, under the air filter box - I have the same issue on my 2011 3.2 and plan on testing the pump this weekend before going to the dealer.

Ken Ramoutar

Thanks. Amazing that I could not find this answer after a lot of internet searching.

sonofsql

turned out my pump is bad and I replaced with an aftermarket for $55.

installation procedure available here (remove the grill around the fog light to see the three 10mm bolts holding it in)

https://workshop-manuals.com/audi/q5...ons/page_4835/