15.2 CO2 indicates you are running rich I believe....
When was the last time the O2 sensor was replaced?

Aside from that....

I suggest you go purchase an aftermarket ignition lock + cylinder for $20 and save yourself a HUGE mess if the key gets stuck!!! You can always get the matched set later, but any day now the key may not turn, or get stuck in which case you need to physically dremel out the lock shield (which is difficult -- ask me how I know...that steel is definitely built to withstand ANY attempt at theft!!!)

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k