Senadye0

I've got about 65k miles on my ride and I'm constantly getting these codes.
Car runs fine. No noticeable differences.

OBD2 - confirmed:
P2187 - System Too Lean at Idle Bank 1

OBD2 - pending:
P2187 - System Too Lean at Idle Bank 1
P2279 - Intake Air System Leak

OBD2 - permanent:
P2187 - System Too Lean at Idle Bank 1
P2279 - Intake Air System Leak

Engine:
P160E
P1009 - Mass air flow (MAF) sensor 1/2, implausible signal from load detection

raj99

Could be an O2 sensor needing to be replaced or a leak in the exhaust, but you also need to include the engine type of your q5 and if you've had the car on a lift to check for any leaks, whether exhaust or around the intake.

Wrex2008

I would first have it checked for vacuum leaks after the MAF (hoses, and little valves can become brittle over time and break), as that seems most likely given the codes you're getting. The car is consuming more air than it thinks it is sucking in, causing a lean condition.

Shouldn't be a major repair based on my experience. Worst leak I ever had actually was a hole in the intake manifold, but it was a simple patch to fix it. Finding the dang thing was the tough part.

If that doesn't work, try cleaning your MAF sensor next (might have 2 of them, I'm not 100% sure though). If that doesn't work I would replace the MAF(s). The reason it runs a lean code is because the MAF isn't reporting the right amount of air coming in through the throttle body, and therefore the car is getting more air than the MAF recognizes (as when it's dirty), and that is exactly what a lean condition is. The leak post MAF sounds more likely to me though.

Senadye0

Found the culprit. It caused a loud hiss or squeal when you hit the throttle.

Oil separator