Andy

if you bridge the two bottom wires on the 3 pin diagnostic connector by the ecu with a paperclip etc the red engine warning light on the centre console will flash the fault code, let me know the sequence and I will look it up for you. This only works whilst the engine/ignition is on after the fault has happened, once you switch the ignition off the code is lost.

Sounds like a dry/corroded electrical connection in part of the engine loom to me, this will cause this kind of fault, swapping sensors therefore does not cure the problem

Good luck