99 V70 P0118 -- ECT Circuit High Input

[ajm]

It's actually possible to replace the ECT sensor without disturbing the thermostat housing at all (it would have been even easier had I done it whilst I had the radiator out and not just after I'd fitted it all back up - doh!)

No harm in doing it the longer way round though, you certainly get a better view of what you're doing.

[E Showell]

Yep. I knew that too, but as a general rule, if I am replacing the ECT, I generally replace the T-stat as well.