Temperature Sensor Failure

[Taber10]

My Ford Zetec SVT has a temperature sensor screwed into the rear top of the block (I believe!) and it has failed once about two years ago, again about two months ago, and then again yesterday!  Does anyone have any hints as to what causes this thing to fail?  The good news is that Ford stocks them, for about $35, I guess because they fit in an '03 Focus, and probably other Fords.  I hate to drive the Cat without being able to monitor the temperature, although overheating hasn't ever been a problem.

Thanks in advance,

[MV8]

Did it set a code/check engine light or is it just that the gauge is not functioning properly?

Blue connector is a push-in sensor where a brown connector is threaded.

Perhaps last time, you paid for an original ford sensor at $35 each but they installed a typical replacement at about $5 each. Can't actually see the difference but the output values may be off or not hold as well.

Edited September 13, 2022 by MV8

[MV8]

I believe your '03 uses the older engine and sensors. The newer sensor is very long and drop into the center of the head.

[Taber10]

Thanks for your reply and especially these parts that I can search for!