diff --git a/selfdrive/debug/check_lag.py b/selfdrive/debug/check_lag.py
new file mode 100755
index 0000000000..418f1f872b
--- /dev/null
+++ b/selfdrive/debug/check_lag.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+import cereal.messaging as messaging
+from cereal.services import service_list
+
+TO_CHECK = ['carState']
+
+
+if __name__ == "__main__":
+  sm = messaging.SubMaster(TO_CHECK)
+
+  prev_t = {}
+
+  while True:
+    sm.update()
+
+    for s in TO_CHECK:
+      if sm.updated[s]:
+        t = sm.logMonoTime[s] / 1e9
+
+        if s in prev_t:
+          expected = 1.0 / (service_list[s].frequency)
+          dt = t - prev_t[s]
+          if dt > 10 * expected:
+            print(t, s, dt)
+
+        prev_t[s] = t