audi8times

I have a 2009 A8 and I have the P0491 and P1411 codes a European shop by my house checked the air injector pump and confirmed it worked, they are claiming that BOTH combi valves are bad, which I find it hard to believe that both pumps would go bad at the same time, I think it's a vacuum leak, they claimed they checked some of the hoses, has anyone else had the combi valves go bad on these cars? the car runs great 110k miles

dvs_dave

SAI system faults are tricky to diagnose and you need to fully understand how it works (refer to SSP’s). You will need a hand vacuum pump and VCDS to be able to test and drive the system for diagnostic purposes.

Both combi valves failing simultaneously is unlikely. Either the pump isn’t delivering sufficient air, (pump is failing or supply hose problem), or there is insufficient vacuum to operate the valves. This could be because of a general vacuum leak, a leak in the SAI vacuum pipes, or a failed SAI solenoid.