The oxygen sensor would generate a "check engine" condition if the codes were pulled...the OVP would not.
I too, would point the fault to the OVP. Replacing it cured the same "hot start" problem I was having a few months ago.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car