^ If by some chance driving the snot out of it for a couple of weeks then clearing the codes doesn't help...
....... 2 codes popping up P219a bank 1 air/fuel ratio imbalance and a P2096 post cat fuel trim system too lean bank 1. .............
Normally when the emissions system detects and imbalance it attempts to correct it with either more or less fuel for the given amount of air that is introduced. It only throws a code if its maxed out its range of adjustments one way or the other yet emissions remain outside spec range. Too lean literally means that emissions are too clean; which results with higher "undesirables" like carbon monoxide output. (extremes can also result with higher cylinder temps, ping, damage) So it's not something that I'd expect for the typical "tune up" items like spark plugs or decarbonization. The vacuum test was a good check. Too high could point to a vac leak.
Confirm, you have the 1.0L GTDI ? What's the mileage?
Check for loose exhaust manifold bolts; common for high mileage vehicles of the past.
I assume you've cleared the codes since the changes and they've come back.
Has this vehicle been altered from stock, including air intake changes? Any post MAP or MAF air leak could throw off ratios. Air intake sensors reading correctly?
There's a sensor 1 and 2 but only a bank 1 per
https://mechanicbase.com/troubleshooting/bank1-vs-bank2/ because we have a single exhaust. Prior to reading that, I was under the impression that bank1=sensor1 and bank2=sensor2. Since the second sensor is only used to detect catalytic converter failure, not adjust fuel trim, I am assuming it's only talking about the pre-cat sensor. Pre and post cat sensors are sometimes the same and can therefore be swapped between positions (as a test) if one of them is suspect.
