diff --git a/board/safety/safety_honda.h b/board/safety/safety_honda.h
index 1e446fa7..0e2acdb4 100644
--- a/board/safety/safety_honda.h
+++ b/board/safety/safety_honda.h
@@ -161,16 +161,25 @@ static int honda_rx_hook(CAN_FIFOMailBox_TypeDef *to_push) {
       }
     }
 
-    // if steering controls messages are received on the destination bus, it's an indication
-    // that the relay might be malfunctioning
     bool stock_ecu_detected = false;
     int bus_rdr_car = (honda_hw == HONDA_BH_HW) ? 0 : 2;  // radar bus, car side
-    if ((safety_mode_cnt > RELAY_TRNS_TIMEOUT) && ((addr == 0xE4) || (addr == 0x194))) {
-      if (((honda_hw != HONDA_N_HW) && (bus == bus_rdr_car)) ||
-        ((honda_hw == HONDA_N_HW) && (bus == 0))) {
+    int pt_bus = (honda_hw == HONDA_BH_HW) ? 1 : 0;
+
+    if (safety_mode_cnt > RELAY_TRNS_TIMEOUT) {
+      // If steering controls messages are received on the destination bus, it's an indication
+      // that the relay might be malfunctioning
+      if ((addr == 0xE4) || (addr == 0x194)) {
+        if (((honda_hw != HONDA_N_HW) && (bus == bus_rdr_car)) || ((honda_hw == HONDA_N_HW) && (bus == 0))) {
+          stock_ecu_detected = true;
+        }
+      }
+      // If Honda Bosch longitudinal mode is selected we need to ensure the radar is turned off
+      // Verify this by ensuring ACC_CONTROL (0x1DF) is not received on the PT bus
+      if (honda_bosch_long && (bus == pt_bus) && (addr == 0x1DF)) {
         stock_ecu_detected = true;
       }
     }
+
     generic_rx_checks(stock_ecu_detected);
   }
   return valid;
@@ -290,6 +299,13 @@ static int honda_tx_hook(CAN_FIFOMailBox_TypeDef *to_send) {
     }
   }
 
+  // Only tester present ("\x02\x3E\x80\x00\x00\x00\x00\x00") allowed on diagnostics address
+  if (addr == 0x18DAB0F1) {
+  if ((GET_BYTES_04(to_send) != 0x00803E02) || (GET_BYTES_48(to_send) != 0x0)) {
+    tx = 0;
+  }
+  }
+
   // 1 allows the message through
   return tx;
 }
diff --git a/python/__init__.py b/python/__init__.py
index 9ec5633c..5c2a781f 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -143,6 +143,9 @@ class Panda(object):
   CLOCK_SOURCE_MODE_FREE_RUNNING = 1
   CLOCK_SOURCE_MODE_EXTERNAL_SYNC = 2
 
+  FLAG_HONDA_ALT_BRAKE = 1
+  FLAG_HONDA_BOSCH_LONG = 2
+
   def __init__(self, serial=None, claim=True):
     self._serial = serial
     self._handle = None
diff --git a/tests/safety/test_honda.py b/tests/safety/test_honda.py
index 11ca4065..173dbcc7 100755
--- a/tests/safety/test_honda.py
+++ b/tests/safety/test_honda.py
@@ -364,6 +364,19 @@ class TestHondaBoschLongSafety(TestHondaBoschSafety):
     }
     return self.packer.make_can_msg_panda("ACC_CONTROL", self.PT_BUS, values)
 
+  def test_diagnostics(self):
+    tester_present = common.package_can_msg((0x18DAB0F1, 0, b"\x02\x3E\x80\x00\x00\x00\x00\x00", self.PT_BUS))
+    self.assertTrue(self.safety.safety_tx_hook(tester_present))
+
+    not_tester_present = common.package_can_msg((0x18DAB0F1, 0, b"\x03\xAA\xAA\x00\x00\x00\x00\x00", self.PT_BUS))
+    self.assertFalse(self.safety.safety_tx_hook(not_tester_present))
+
+  def test_radar_alive(self):
+    # If the radar knockout failed, make sure the relay malfunction is shown
+    self.assertFalse(self.safety.get_relay_malfunction())
+    self._rx(make_msg(self.PT_BUS, 0x1DF, 8))
+    self.assertTrue(self.safety.get_relay_malfunction())
+
   def test_gas_safety_check(self):
     for controls_allowed in [True, False]:
       for gas in np.arange(self.NO_GAS, self.MAX_GAS + 2000, 100):