Land Rover Repair: Discovery Series I code issues, rocker shafts, discovery series

Question
John,
I do not expect you to recall, but I had asked recently about getting an O2 sensor rich (1158) code after doing some top-end work, specifically, replacing the rocker shafts. During this work, plugs and wires were replaced, and all rockers were cleaned, all new gaskets used on build-up. The code comes back, over and over again, but for one day only, I had a code for O2 sensor high voltage, but once cleared, nearly two weeks ago; it has not returned. I am getting a "not ready" on catalyst and evap, along with the recurring 1158 code. No performance issues, no loss of gas mileage, etc. Any ideas?
Thanks,
Michael

Answer
Situations like this are what the live data screen on the factory T4 test system are for.  The T4 has a mode where it shows all the parameters on a single screen and highlights out-range ones in grey.  Then you can look further into why that particular thing is "off." In my experience that is the only efficient path to resolve situations like yours.  I don't know any way other than to attack it with what are really the only proper tools for the situation.

Without seeing everything in relation at one, you could guess forever

John