98 Town & Country P1491 engine code

I have a 1998 Town and Country and last week the cooling fans quit working and I determined that is was the Coolin Fan Relay and replaced it , the fans started working correctly and then a couple of days the the servie engine light came on it is started getting hot again . The fans were kicking on but only for about 10 - 20 seconds at a time , had the light checked and it comes up P1491 , since I have replaced the Fan Relay could it be the temperature cooling sensor since the fans are coming on but not long enough.

Sounds like a bad relay switch.