diff --git a/selfdrive/car/tests/test_car_interfaces.py b/selfdrive/car/tests/test_car_interfaces.py
index d44c50ed90..490c849863 100755
--- a/selfdrive/car/tests/test_car_interfaces.py
+++ b/selfdrive/car/tests/test_car_interfaces.py
@@ -7,7 +7,7 @@ from hypothesis import Phase, given, settings
 import importlib
 from parameterized import parameterized
 
-from cereal import car
+from cereal import car, messaging
 from openpilot.common.realtime import DT_CTRL
 from openpilot.selfdrive.car import gen_empty_fingerprint
 from openpilot.selfdrive.car.car_helpers import interfaces
@@ -119,6 +119,12 @@ class TestCarInterfaces(unittest.TestCase):
        hasattr(radar_interface, '_update') and hasattr(radar_interface, 'trigger_msg'):
       radar_interface._update([radar_interface.trigger_msg])
 
+    # Test radar fault
+    if not car_params.radarUnavailable and radar_interface.rcp is not None:
+      cans = [messaging.new_message('can', 1).to_bytes() for _ in range(5)]
+      rr = radar_interface.update(cans)
+      self.assertTrue(rr is None or len(rr.errors) > 0)
+
   def test_interface_attrs(self):
     """Asserts basic behavior of interface attribute getter"""
     num_brands = len(get_interface_attr('CAR'))
diff --git a/selfdrive/controls/tests/test_leads.py b/selfdrive/controls/tests/test_leads.py
new file mode 100644
index 0000000000..bd8baf096e
--- /dev/null
+++ b/selfdrive/controls/tests/test_leads.py
@@ -0,0 +1,36 @@
+#!/usr/bin/env python3
+import unittest
+
+import cereal.messaging as messaging
+
+from selfdrive.test.process_replay import replay_process_with_name
+from selfdrive.car.toyota.values import CAR as TOYOTA
+
+
+class TestLeads(unittest.TestCase):
+  def test_radar_fault(self):
+    # if there's no radar-related can traffic, radard should either not respond or respond with an error
+    # this is tightly coupled with underlying car radar_interface implementation, but it's a good sanity check
+    def single_iter_pkg():
+      # single iter package, with meaningless cans and empty carState/modelV2
+      msgs = []
+      for _ in range(5):
+        can = messaging.new_message("can", 1)
+        cs = messaging.new_message("carState")
+        msgs.append(can.as_reader())
+        msgs.append(cs.as_reader())
+      model = messaging.new_message("modelV2")
+      msgs.append(model.as_reader())
+
+      return msgs
+
+    msgs = [m for _ in range(3) for m in single_iter_pkg()]
+    out = replay_process_with_name("radard", msgs, fingerprint=TOYOTA.COROLLA_TSS2)
+    states = [m for m in out if m.which() == "radarState"]
+    failures = [not state.valid and len(state.radarState.radarErrors) for state in states]
+
+    self.assertTrue(len(states) == 0 or all(failures))
+
+
+if __name__ == "__main__":
+  unittest.main()