P0325 and P0440 Fault Codes in 1998 Mercury Villager: What Do They Mean and How to Diagnose?

I recently encountered two diagnostic trouble codes, P0325 and P044-0, on my 1998 Mercury Villager after hearing a loud bang while driving. The vehicle is currently running smoothly, but I'm concerned about the underlying cause of these codes. While I understand what each code indicates based on the onboard computer, I'm unsure whether they point to faulty sensors or a more serious mechanical issue. To assess this further, I've reset the codes and am monitoring for any recurrence—especially if a knocking sound returns. If the codes reappear, it may suggest an ongoing problem that requires professional diagnosis. I'd appreciate insights on how to interpret these codes accurately and whether they warrant immediate attention or can be safely monitored.