Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 5 reviews
The P0483 is detecting that, while idling, when the fans are turned on by the ECU, the coolant temperature doesn't drop down. That could be due to bad relays (there's two), blown fuse (also 2) or failing fan motor (one or both). As both fans seemed to be working later, it's possible that the relay connector blades (where it plugs into the fuse box) weren't making good contact, and by taking the relay out and replacing it, the contact was restored. But that's only one possibility. But it's not a bad idea to pull both relays, check/clean the contacts and replace, whether or not that's the original cause.
The fan motors can become intermittent, which could lead to the same symptom. If the CEL reappears, before doing anything, open the hood and check if both fans are running. (The CEL will come on after the fault is detected in two consecutive drive cycles.)
I've attached a wiring diagram to show what's involved.