What makes a GPS IFR certified?
To be legal as a primary source of navigation under IFR, the GPS must certified as a TSO C129 (non-WAAS) or TSO C145/146 (WAAS) receiver. Additionally the database must be current. There are some manufacturer-specific exceptions (Check your flight-manual supplement. It is interesting to note that there is no requirement for navigational equipment such as VOR and GPS, but you must have them equipped if you intend to use their associated facilities. Since IFR procedures rely heavily on these types of navigational equipment, you won’t go far without them.VFR and handheld GPS systems are not authorized for IFR navigation, instrument approaches, or as a primary instrument flight reference. During IFR operations they may be considered only an aid to situational awareness.The aircraft itself has to be able to be IFR certified. You can find this information in the EASA type certificate list (TCDS). A search in the database can come out like this: A note in the POH or a placard in the cockpit stating “VFR only” will also prevent you from flying IFR with that aircraft.