diff --git a/libraries/AP_NavEKF3/AP_NavEKF3.cpp b/libraries/AP_NavEKF3/AP_NavEKF3.cpp
index 0cace3d613..2225ab8126 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3.cpp
@@ -1070,7 +1070,7 @@ bool NavEKF3::pre_arm_check(char *failure_msg, uint8_t failure_msg_len) const
     // check if using compass (i.e. EK3_SRCn_YAW) with deprecated MAG_CAL values (5 was EXTERNAL_YAW, 6 was EXTERNAL_YAW_FALLBACK)
     const int8_t magCalParamVal = _magCal.get();
     const AP_NavEKF_Source::SourceYaw yaw_source = sources.getYawSource();
-    if (((magCalParamVal == 5) || (magCalParamVal == 6)) && (yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL)) {
+    if (((magCalParamVal == 5) || (magCalParamVal == 6)) && (yaw_source != AP_NavEKF_Source::SourceYaw::GPS)) {
         // yaw source is configured to use compass but MAG_CAL valid is deprecated
         AP::dal().snprintf(failure_msg, failure_msg_len, "EK3_MAG_CAL and EK3_SRC1_YAW inconsistent");
         return false;
@@ -1672,11 +1672,11 @@ void NavEKF3::convert_parameters()
     switch (_magCal.get()) {
     case 5:
         // EK3_MAG_CAL = 5 (External Yaw sensor).  We rely on effective_magCal to interpret old "5" values as "Never"
-        AP_Param::set_and_save_by_name("EK3_SRC1_YAW", (int8_t)AP_NavEKF_Source::SourceYaw::EXTERNAL);
+        AP_Param::set_and_save_by_name("EK3_SRC1_YAW", (int8_t)AP_NavEKF_Source::SourceYaw::GPS);
         break;
     case 6:
         // EK3_MAG_CAL = 6 (ExtYaw with Compass fallback).  We rely on effective_magCal to interpret old "6" values as "When Flying"
-        AP_Param::set_and_save_by_name("EK3_SRC1_YAW", (int8_t)AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK);
+        AP_Param::set_and_save_by_name("EK3_SRC1_YAW", (int8_t)AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK);
         break;
     default:
         // do nothing
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
index ce53e213fb..4aea462831 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
@@ -513,7 +513,7 @@ bool NavEKF3_core::use_compass(void) const
 {
     const AP_NavEKF_Source::SourceYaw yaw_source = frontend->sources.getYawSource();
     if ((yaw_source != AP_NavEKF_Source::SourceYaw::COMPASS) &&
-        (yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK)) {
+        (yaw_source != AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK)) {
         // not using compass as a yaw source
         return false;
     }
@@ -528,7 +528,7 @@ bool NavEKF3_core::use_compass(void) const
 bool NavEKF3_core::using_external_yaw(void) const
 {
     const AP_NavEKF_Source::SourceYaw yaw_source = frontend->sources.getYawSource();
-    if (yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL || yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK ||
+    if (yaw_source == AP_NavEKF_Source::SourceYaw::GPS || yaw_source == AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK ||
         yaw_source == AP_NavEKF_Source::SourceYaw::GSF || !use_compass()) {
         return imuSampleTime_ms - last_gps_yaw_fusion_ms < 5000 || imuSampleTime_ms - lastSynthYawTime_ms < 5000;
     }
@@ -599,7 +599,7 @@ void NavEKF3_core::checkGyroCalStatus(void)
     // check delta angle bias variances
     const float delAngBiasVarMax = sq(radians(0.15f * dtEkfAvg));
     const AP_NavEKF_Source::SourceYaw yaw_source = frontend->sources.getYawSource();
-    if (!use_compass() && (yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL) && (yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK) &&
+    if (!use_compass() && (yaw_source != AP_NavEKF_Source::SourceYaw::GPS) && (yaw_source != AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK) &&
         (yaw_source != AP_NavEKF_Source::SourceYaw::EXTNAV)) {
         // rotate the variances into earth frame and evaluate horizontal terms only as yaw component is poorly observable without a yaw reference
         // which can make this check fail
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_MagFusion.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_MagFusion.cpp
index 00149d65d5..2e071d10d1 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_MagFusion.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_MagFusion.cpp
@@ -223,8 +223,8 @@ void NavEKF3_core::SelectMagFusion()
     // flight using the output from the GSF yaw estimator.
     if ((yaw_source == AP_NavEKF_Source::SourceYaw::GSF) ||
         (!use_compass() &&
-         yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL &&
-         yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK &&
+         yaw_source != AP_NavEKF_Source::SourceYaw::GPS &&
+         yaw_source != AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK &&
          yaw_source != AP_NavEKF_Source::SourceYaw::EXTNAV)) {
 
         // because this type of reset event is not as time critical, require a continuous history of valid estimates
@@ -259,14 +259,14 @@ void NavEKF3_core::SelectMagFusion()
     }
 
     // Handle case where we are using GPS yaw sensor instead of a magnetomer
-    if (yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL || yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK) {
+    if (yaw_source == AP_NavEKF_Source::SourceYaw::GPS || yaw_source == AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK) {
         bool have_fused_gps_yaw = false;
         if (storedYawAng.recall(yawAngDataDelayed,imuDataDelayed.time_ms)) {
             if (tiltAlignComplete && (!yawAlignComplete || yaw_source_reset)) {
                 alignYawAngle(yawAngDataDelayed);
                 yaw_source_reset = false;
             } else if (tiltAlignComplete && yawAlignComplete) {
-                fuseEulerYaw(yawFusionMethod::EXTERNAL);
+                fuseEulerYaw(yawFusionMethod::GPS);
             }
             have_fused_gps_yaw = true;
             last_gps_yaw_fusion_ms = imuSampleTime_ms;
@@ -286,7 +286,7 @@ void NavEKF3_core::SelectMagFusion()
                 lastSynthYawTime_ms = imuSampleTime_ms;
             }
         }
-        if (yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL) {
+        if (yaw_source == AP_NavEKF_Source::SourceYaw::GPS) {
             // no fallback
             return;
         }
@@ -362,9 +362,9 @@ void NavEKF3_core::SelectMagFusion()
         magTimeout = true;
     }
 
-    if (yaw_source != AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK) {
+    if (yaw_source != AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK) {
         // check for and read new magnetometer measurements. We don't
-        // read for EXTERNAL_COMPASS_FALLBACK as it has already been read
+        // read for GPS_COMPASS_FALLBACK as it has already been read
         // above
         readMagData();
     }
@@ -375,7 +375,7 @@ void NavEKF3_core::SelectMagFusion()
     // Control reset of yaw and magnetic field states if we are using compass data
     if (magDataToFuse) {
         if (yaw_source_reset && (yaw_source == AP_NavEKF_Source::SourceYaw::COMPASS ||
-                                 yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK)) {
+                                 yaw_source == AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK)) {
             magYawResetRequest = true;
             yaw_source_reset = false;
         }
@@ -887,7 +887,7 @@ bool NavEKF3_core::fuseEulerYaw(yawFusionMethod method)
     // yaw measurement error variance (rad^2)
     float R_YAW;
     switch (method) {
-    case yawFusionMethod::EXTERNAL:
+    case yawFusionMethod::GPS:
         R_YAW = sq(yawAngDataDelayed.yawAngErr);
         break;
 
@@ -913,7 +913,7 @@ bool NavEKF3_core::fuseEulerYaw(yawFusionMethod method)
     // determine if a 321 or 312 Euler sequence is best
     rotationOrder order;
     switch (method) {
-    case yawFusionMethod::EXTERNAL:
+    case yawFusionMethod::GPS:
         order = yawAngDataDelayed.order;
         break;
 
@@ -1074,7 +1074,7 @@ bool NavEKF3_core::fuseEulerYaw(yawFusionMethod method)
         break;
     }
 
-    case yawFusionMethod::EXTERNAL:
+    case yawFusionMethod::GPS:
         // both external sensor yaw and last yaw when static are stored in yawAngDataDelayed.yawAng
         innovYaw = wrap_PI(yawAngPredicted - yawAngDataDelayed.yawAng);
         break;
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
index 58e6079afe..d259b31ab3 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
@@ -1290,7 +1290,7 @@ float NavEKF3_core::MagDeclination(void) const
 void NavEKF3_core::updateMovementCheck(void)
 {
     const AP_NavEKF_Source::SourceYaw yaw_source = frontend->sources.getYawSource();
-    const bool runCheck = onGround && (yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL || yaw_source == AP_NavEKF_Source::SourceYaw::EXTERNAL_COMPASS_FALLBACK ||
+    const bool runCheck = onGround && (yaw_source == AP_NavEKF_Source::SourceYaw::GPS || yaw_source == AP_NavEKF_Source::SourceYaw::GPS_COMPASS_FALLBACK ||
                                        yaw_source == AP_NavEKF_Source::SourceYaw::EXTNAV || yaw_source == AP_NavEKF_Source::SourceYaw::GSF || !use_compass());
     if (!runCheck)
     {
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index b6c06a3be0..4f14aee997 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -123,7 +123,7 @@ bool NavEKF3_core::setup_core(uint8_t _imu_index, uint8_t _core_index)
         // initialise to same length of IMU to allow for multiple wheel sensors
         return false;
     }
-    if(frontend->sources.ext_yaw_enabled() && !storedYawAng.init(obs_buffer_length)) {
+    if(frontend->sources.gps_yaw_enabled() && !storedYawAng.init(obs_buffer_length)) {
         return false;
     }
     // Note: the use of dual range finders potentially doubles the amount of data to be stored
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.h b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
index 4851d7a57f..ca08eb31d4 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.h
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
@@ -621,7 +621,7 @@ private:
     // specifies the method to be used when fusing yaw observations
     enum class yawFusionMethod {
 	    MAGNETOMETER=0,
-	    EXTERNAL=1,
+	    GPS=1,
         GSF=2,
         STATIC=3,
         PREDICTED=4,