A Co Carlow homeowner woken by noise later found the catalytic converter was gone from the car outside.
It was missing from the bronze-coloured Toyota Yaris which was parked in the driveway.
Three men in dark clothing were seen leaving the area just before midnight on Friday last (4th March).
Between Wednesday, 23rd February and Friday, 25th February, there was a separate, similar theft from a blue Toyota Yaris at Poachers Lock in Leighlinbridge.
Anybody with information on either incident is asked to contact their local Garda station.