BINGO FRAUKE. Thanks for your input.

Last night as I was about to get the codes out of the diag ports again, it occurred to me that the MAS symptoms and the air temp sensor faults were to do with the same connector. The one on the MAS. So I had a quick look at it. I hardly moved it and it started smoking. And then the outside started to burn! I quickly ran to turn off the ignition and then cut open the harness that runs to the MAS. No insulation present in there, just corroded copper. Guess that answers the question over whether my car has the bio-degradable harness.

Guess it's time to start searching the forums for choices to do with engine wiring harnesses. DOH!