2003 s-type coolant temp sensor issues

Hi all,

Recently purchased my first jag, the 2003 s-type 4.2L and im having an issue.

after clearing up all the leaks and replacing aging hoses, ive come across an issue with the coolant temp as its reading -30 when engine is left over night.

When engine is at temp, it only reaches 24deg, not enough to trigger the fan controls.

is there some way to reset the value, ive already replaced the temp sensor and checked over the majority of the wiring at this point, pulling my hair out 🙂