The GPS has to be rated, there are also requirements for the plane to fly IFR in 91.205: https://www.law.cornell.edu/cfr/text/14/91.205 https://www.law.cornell

The GPS has to be rated, there are also requirements for the plane to fly IFR in 91.205: https://www.law.cornell.edu/cfr/text/14/91.205 https://www.law.cornell.edu/cfr/text/14/91.205 One mnenonic is GRABCARD Generator Radios Attitude indicator Ball Clock Adjustable altimeter Rate of turn indicator Directional gyro