I am hoping to get some help with diagnosing an SAI fault, specifically P0411 secondary air injection - Incorrect Flow. I know that this has been gone over ad nauseum online in many different forums and videos on youtube, etc. I have seen a ton of them trying to resolve this issue. The #1 issue that's said is vacuum hoses or SAI pump failure or beginning to fail. I am no pro mechanic just your average do it yourselfer and I have owned this car since 2009. I have done myriad repairs on the car all successfully so I assumed the SAI system would be only moderately challenging at best. I have seen all the articles, videos, etc and have checked the system top to bottom. I have cleared the code and drove the car until the code returned. I have use my Vag OBDII device and run measuring blocks and basic functions to ascertain which items work, don't work, etc. I have replaced both combi valves (twice), once to change them out and a second time after I took them off of the car to check if they were faulty, which they weren't, and to clean out the cylinder head passageways that they connect to on the block. I have replaced the pump, the hose from pump to airbox, the hose from pump to block that runs to each kombi valve, check valve, all vac lines, to see if they hold vacuum, the SAI solenoid N112, and the IMT valve N156. And they both hold vacuum and spec out to 29 ohms with a multimeter. the range per the Bentley manual I have is 25-35. Removed, checked and cleaned the rotary change over valve in the intake manifold, the intake manifold changeover vacuum valve attached to it at the front of the IM, I have tested the vacuum reservoir for leaks, none. I have run diags through basic settings for block 71 Evap, syst OK. 34 for O2 sensors once the car was warm enough at between 1800-2200 rpm, B1-P1 ok, B2-p2 ok, Test 77 always comes back Syst. N. Ok. I have heard all the solenoids clicking as I run the individual tests.

I have checked everything to do with this so called simple system and all the parts seem to work. I have not checked the relay or fuse because i assume my pump would not run if one or the other were bad. I have removed the tube coming from SAI pump on cold start and it is blowing a very generous amount of air so i know its reaching the combi valves.

When I have cleared the DTC and then proceed to run the test 77 it fails and returns the check engine light. I am stumped. I basically went the non mechanic route initially and bought new parts. Then later started doing testing. I feel that the problem is definitely not the combi's or any large parts as they all work. I've replaced all the vacuum hoses and they are connected right as verified by pics online and the Bentley book. I cannot pass emissions since I live in a state that has them and I do not want to do a delete as that involves a programmer to work on the computer.

If anyone has any suggestions I am open to hearing them. Or if you have been through it and see something I may not. This is truly a frustrating issue and I am stymied!!

Thank you.