diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index 9333dd3db5..78bb6c2470 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -113,33 +113,34 @@ bool NavEKF3_core::setup_core(uint8_t _imu_index, uint8_t _core_index)
     if(!storedBaro.init(obs_buffer_length)) {
         return false;
     }
-    if(!storedTAS.init(obs_buffer_length)) {
+    if(dal.airspeed() && !storedTAS.init(obs_buffer_length)) {
         return false;
     }
-    if (!storedOF.init(flow_buffer_length)) {
+    if(dal.opticalflow_enabled() && !storedOF.init(flow_buffer_length)) {
         return false;
     }
-    if(!storedBodyOdm.init(obs_buffer_length)) {
+    if(frontend->sources.ext_nav_enabled() && !storedBodyOdm.init(obs_buffer_length)) {
         return false;
     }
-    if(!storedWheelOdm.init(imu_buffer_length)) { // initialise to same length of IMU to allow for multiple wheel sensors
+    if(frontend->sources.wheel_encoder_enabled() && !storedWheelOdm.init(imu_buffer_length)) {
+        // initialise to same length of IMU to allow for multiple wheel sensors
         return false;
     }
-    if(!storedYawAng.init(yaw_angle_buffer_length)) {
+    if(frontend->sources.ext_yaw_enabled() && !storedYawAng.init(yaw_angle_buffer_length)) {
         return false;
     }
     // Note: the use of dual range finders potentially doubles the amount of data to be stored
-    if(!storedRange.init(MIN(2*obs_buffer_length , imu_buffer_length))) {
+    if(dal.rangefinder() && !storedRange.init(MIN(2*obs_buffer_length , imu_buffer_length))) {
         return false;
     }
     // Note: range beacon data is read one beacon at a time and can arrive at a high rate
-    if(!storedRangeBeacon.init(imu_buffer_length+1)) {
+    if(dal.beacon() && !storedRangeBeacon.init(imu_buffer_length+1)) {
         return false;
     }
-    if (!storedExtNav.init(extnav_buffer_length)) {
+    if (frontend->sources.ext_nav_enabled() && !storedExtNav.init(extnav_buffer_length)) {
         return false;
     }
-    if (!storedExtNavVel.init(extnav_buffer_length)) {
+    if (frontend->sources.ext_nav_enabled() && !storedExtNavVel.init(extnav_buffer_length)) {
         return false;
     }
     if(!storedIMU.init(imu_buffer_length)) {