My parking sensors work fine during the day when it is warm but don't work properly in the evening when it gets cool, and cool isn't that cool as I live in Southern Spain.

Anyone else noticed this or has any suggestions for a fix

Thanks

You should check each sensor as the cause is most likely condensation caused by the change in temp. Check all are sitting ok and the seals are in good nick. A diagnostic check at a dealer or good garage will be able to tell you which one(s) are playing up. As individual components they are relatively cheap and easy to replace.