diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.cpp b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
index 1a4defa696..d893443c83 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
@@ -636,13 +636,14 @@ AP_InertialSensor::init(uint16_t sample_rate)
     _have_sample = false;
 }
 
-void AP_InertialSensor::_add_backend(AP_InertialSensor_Backend *backend)
+bool AP_InertialSensor::_add_backend(AP_InertialSensor_Backend *backend)
 {
     if (!backend)
-        return;
+        return false;
     if (_backend_count == INS_MAX_BACKENDS)
         AP_HAL::panic("Too many INS backends");
     _backends[_backend_count++] = backend;
+    return true;
 }
 
 /*
@@ -678,26 +679,37 @@ AP_InertialSensor::detect_backends(void)
     _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.i2c_mgr->get_device(HAL_INS_MPU60x0_I2C_BUS, HAL_INS_MPU60x0_I2C_ADDR)));
     _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME)));
 #elif HAL_INS_DEFAULT == HAL_INS_PX4 || HAL_INS_DEFAULT == HAL_INS_VRBRAIN
-    if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_TEST_V1) {
+
+    if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PX4V1) {
         _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_MPU60x0_NAME)));
-    } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_TEST_V2) {
+
+    } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXHAWK) {
         _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_MPU60x0_NAME), ROTATION_ROLL_180));
         _add_backend(AP_InertialSensor_LSM9DS0::probe(*this,
                                                       hal.spi->get_device(HAL_INS_LSM9DS0_G_NAME),
                                                       hal.spi->get_device(HAL_INS_LSM9DS0_A_NAME), ROTATION_ROLL_180));
-    } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_TEST_V3) {
-        _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_EXT_NAME), true, ROTATION_PITCH_180));
+
+    } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXHAWK2) {
+        // older Pixhawk2 boards have the MPU6000 instead of MPU9250
+        if (!_add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_EXT_NAME), true, ROTATION_PITCH_180))) {
+            _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_MPU60x0_EXT_NAME), ROTATION_PITCH_180));
+        }
         _add_backend(AP_InertialSensor_LSM9DS0::probe(*this,
                                                       hal.spi->get_device(HAL_INS_LSM9DS0_EXT_G_NAME),
                                                       hal.spi->get_device(HAL_INS_LSM9DS0_EXT_A_NAME), ROTATION_ROLL_180_YAW_270));
-        _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME), false, ROTATION_YAW_270));
+        if (!_add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME), false, ROTATION_YAW_270))) {
+            _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_MPU60x0_NAME), ROTATION_YAW_270));
+        }
+
     } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXRACER) {
         _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_ICM20608_NAME), ROTATION_ROLL_180_YAW_90));
         _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME), false, ROTATION_ROLL_180_YAW_90));
+
     } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PHMINI) {
         // PHMINI uses ICM20608 on the ACCEL_MAG device and a MPU9250 on the old MPU6000 CS line
         _add_backend(AP_InertialSensor_MPU6000::probe(*this, hal.spi->get_device(HAL_INS_ICM20608_AM_NAME), ROTATION_ROLL_180));
         _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME), false, ROTATION_ROLL_180));
+
     } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PH2SLIM) {
         _add_backend(AP_InertialSensor_MPU9250::probe(*this, hal.spi->get_device(HAL_INS_MPU9250_NAME), true, ROTATION_YAW_270));        
     }
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.h b/libraries/AP_InertialSensor/AP_InertialSensor.h
index f3010cc9b4..c34d961d7b 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.h
@@ -259,7 +259,7 @@ public:
 private:
 
     // load backend drivers
-    void _add_backend(AP_InertialSensor_Backend *backend);
+    bool _add_backend(AP_InertialSensor_Backend *backend);
     void _start_backends();
     AP_InertialSensor_Backend *_find_backend(int16_t backend_id, uint8_t instance);