SQ5.TO

Wow - that looks awful.
Did you notice something in the performance that prompted the need to clean out?
I have the same issue on an X6, my mechanic tells me this is typical for BMW's as well. Told me its about a 4 hour job though, funny how the dealer can stretch it to 19.
Hope that it will be good for another 130K now.

New2Audi20241

Hello, I own a 2012 Audi 3.2 Q5, Initially I had a steady P4091 and P4092. We did a deep carbon cleaning, put the car back together and now I am getting a intermittent code of P4091. The code will turn on and off between several miles of driving. I have changed the Secondary Air injection Pump, the secondary Air injection air mass sensor, and the secondary air injection pump check valve. Has anyone had this problem before? Over all the car runs fine but I would like to narrow down where this code is coming from.

S4'ed

Either a cracked plastic air injection hose,
- or a sticky SAI Combi Valve,
- or the vacuum control solenoids (vacuum hoses or wiring or valves) which control the Combi Valves,
- or you did not clean all the deposits out of the passages in the cylinder heads. There is one larger passage that runs from the front to the back of the head (plugged in the front, Combi-Valve on the back, and then there are 3 smaller passages, at a right angle to the front-to-back passage, that leads to each of the 3 exhaust ports. Those 3 smaller passages are more difficult to clean out.