My (electrical) temperature gauge is not working or shows the wrong temperature.

Check for adequate ground connection - improper grounding generally accounts for most gauge inconsistencies.

Ensure that Teflon tape or other sealants have not been placed on the temperature sender threads. These sealants can cause ground isolation from the system creating an improper ground to the gauge.

Ensure that the gauge and sender are compatible. To do this, reference the manufacturer's recommended gauge/sender combination.