AU did not pass… CO and Lambda too high

Hello, what does it point out if Lambda and CO are a bit too high? Is a Chrysler 300M 2.7 V6 12/2003 for 10 years with LPG gas system, mileage 223,000km of which about 100,000 on gas. Otherwise find only old contributions to Lambda lower and CO too high but nothing too high. The KATs were checked by endoscope for visible damage, both ok. The certificate shows that the two Vot-Kat probes are ok, right? I understand correctly that Bank 2 with 0.9mV more, Is it also clear that the after-cat probes (monitor probes) are also in order?