My Audi has been boosting less lately, and fuel consumption is up so I got a dude to read the fault codes:
00537 - Lambda (Oxygen Sensor) Regulation
08-10 - Control Limit Surpassed - Intermittent
00525 - Oxygen (Lambda) Sensor (G39)
29-00 - Short to Ground
00561 - Mixture Adaptation
12-00 - Adaptation Limit (Mul) Exceeded
The oxygen sensor is max two years old (Bosch unit), could it be on its last legs already? The MAF was replaced a year ago with a new, rebuilt Bosch-unit.
Could something else cause this?