Mrs C's 147 TS has been getting a little grumpy about starting and lo, it finally threw a CEL this morning. Sure enough P0335. According to Jamie Porter's pictures it looks pretty simple.
I did this job many years ago on a 2L TS. 'Memory is getting a bit thin but I seem to remember it was pretty easy. What's not abundantly clear from Jamie's pictures is that you get at the wiring from the top but the sensor itself from underneath. It's located towards the rear so you'll need enough height to slide under the engine to access it.