diff --git a/ArduSub/system.cpp b/ArduSub/system.cpp
index 2f05066c31..84293f5574 100644
--- a/ArduSub/system.cpp
+++ b/ArduSub/system.cpp
@@ -40,13 +40,16 @@ void Sub::init_ardupilot()
     switch (AP_BoardConfig::get_board_type()) {
     case AP_BoardConfig::PX4_BOARD_PIXHAWK2:
         AP_Param::set_by_name("GND_EXT_BUS", 0);
+        celsius.init(0);
         break;
     default:
         AP_Param::set_by_name("GND_EXT_BUS", 1);
+        celsius.init(1);
         break;
     }
 #else
     AP_Param::set_default_by_name("GND_EXT_BUS", 1);
+    celsius.init(1);
 #endif
 
     // identify ourselves correctly with the ground station
@@ -71,8 +74,6 @@ void Sub::init_ardupilot()
 
     barometer.init();
 
-    celsius.init();
-
     // Register the mavlink service callback. This will run
     // anytime there are more than 5ms remaining in a call to
     // hal.scheduler->delay.
diff --git a/libraries/AP_TemperatureSensor/TSYS01.cpp b/libraries/AP_TemperatureSensor/TSYS01.cpp
index ed0bf3a6d7..a11c13740d 100644
--- a/libraries/AP_TemperatureSensor/TSYS01.cpp
+++ b/libraries/AP_TemperatureSensor/TSYS01.cpp
@@ -13,9 +13,9 @@ static const uint8_t TSYS01_CMD_READ_PROM   = 0xA0;
 static const uint8_t TSYS01_CMD_CONVERT     = 0x40;
 static const uint8_t TSYS01_CMD_READ_ADC    = 0x00;
 
-bool TSYS01::init()
+bool TSYS01::init(uint8_t bus)
 {
-    _dev = std::move(hal.i2c_mgr->get_device(1, TSYS01_ADDR));
+    _dev = std::move(hal.i2c_mgr->get_device(bus, TSYS01_ADDR));
     if (!_dev) {
         printf("TSYS01 device is null!");
         return false;
diff --git a/libraries/AP_TemperatureSensor/TSYS01.h b/libraries/AP_TemperatureSensor/TSYS01.h
index 2d1556adf2..5c19234f8a 100644
--- a/libraries/AP_TemperatureSensor/TSYS01.h
+++ b/libraries/AP_TemperatureSensor/TSYS01.h
@@ -13,7 +13,7 @@
 class TSYS01 {
 public:
 
-    bool init(void);
+    bool init(uint8_t bus);
     float temperature(void) { return _temperature; } // temperature in degrees C
     bool healthy(void) { // do we have a valid temperature reading?
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL