Here are, in generic terms, some items that can cause elevated CO readings:
1. dirty or restricted airfilter
2. contaminated oil
3. saturated charcoal canister
4. non-functioning PCV system
5. dripping fuel injector (s).
I am still puzzled, how you can have a high lambda reading ( indicating a lean fuel mixture ), and yet have high CO's.
When was the last time this exhaust gas analyzer was calibrated ?
2007 C 230 Sport.