Deep vein thrombosis causes warmth, pyrexia?

Not usually: Deep vein thrombosis, if it causes any symptoms at all, generally presents with swelling and pain of the affected limb. "pyrexia" or fever would only be present with an inflammatory or infectious thrombophlebitis, a much less commonn disorder and one which is quite serious.

Unusual: The only time a DVT would cause pyrexia (a fever) would be if there was an infection assciated with it. Although that can happen, it would be exceedingly rare.