diff --git a/python/uds.py b/python/uds.py
index 41f4e98d62..ed0404a6f0 100644
--- a/python/uds.py
+++ b/python/uds.py
@@ -103,7 +103,8 @@ def _isotp_thread(panda, bus, tx_addr, tx_queue, rx_queue):
       filter_addr = (tx_addr & 0xFFFF0000) + (tx_addr<<8 & 0xFF00) + (tx_addr>>8 & 0xFF)
     else:
       raise ValueError("invalid tx_addr: {}".format(tx_addr))
-    rx_frame = {"size": 0, "data": "", "sent": True}
+    rx_frame = {"size": 0, "data": "", "idx": 0, "done": True}
+    tx_frame = {"size": 0, "data": "", "idx": 0, "done": True}
 
     # clear tx buffer
     panda.can_clear(bus)
@@ -121,34 +122,64 @@ def _isotp_thread(panda, bus, tx_addr, tx_queue, rx_queue):
           # single rx_frame
           rx_frame["size"] = rx_data[0] & 0xFF
           rx_frame["data"] = rx_data[1:1+rx_frame["size"]]
-          rx_frame["sent"] = True
+          rx_frame["idx"] = 0
+          rx_frame["done"] = True
           rx_queue.put(rx_frame["data"])
         elif rx_data[0] >> 4 == 0x1:
           # first rx_frame
           rx_frame["size"] = ((rx_data[0] & 0x0F) << 8) + rx_data[1]
           rx_frame["data"] = rx_data[2:]
-          rx_frame["sent"] = False
+          rx_frame["idx"] = 0
+          rx_frame["done"] = False
           # send flow control message (send all bytes)
-          flow_ctl = "\x30\x00\x00".ljust(8, "\x00")
-          if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(flow_ctl)))
-          panda.can_send(tx_addr, flow_ctl, bus)
+          msg = "\x30\x00\x00".ljust(8, "\x00")
+          if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(msg)))
+          panda.can_send(tx_addr, msg, bus)
         elif rx_data[0] >> 4 == 0x2:
-          # consecutive rx_frame
-          assert rx_frame["sent"] == False, "no active frame"
+          # consecutive rx frame
+          assert rx_frame["done"] == False, "rx: no active frame"
+          # validate frame index
+          rx_frame["idx"] += 1
+          assert rx_frame["idx"] & 0xF == rx_data[0] & 0xF, "rx: invalid consecutive frame index"
           rx_size = rx_frame["size"] - len(rx_frame["data"])
           rx_frame["data"] += rx_data[1:1+min(rx_size, 7)]
-          if rx_size <= 7:
-            rx_frame["sent"] = True
+          if rx_frame["size"] == len(rx_frame["data"]):
+            rx_frame["done"] = True
             rx_queue.put(rx_frame["data"])
+        elif rx_data[0] >> 4 == 0x3:
+          # flow control
+          assert tx_frame["done"] == False, "tx: no active frame"
+          # TODO: support non-zero block size and separate time
+          assert rx_data[0] == 0x30 and rx_data[2] == 0x00, "tx: flow-control requires: continue, no delay"
+          # first frame = 6 bytes, each consecutive frame = 7 bytes
+          start = 6 + tx_frame["idx"] * 7
+          count = rx_data[1]
+          end = start + count * 7 if count > 0 else tx_frame["size"]
+          for i in range(start, end, 7):
+            tx_frame["idx"] += 1
+            # consecutive tx frames
+            msg = (chr(0x20 | (tx_frame["idx"] & 0xF)) + tx_frame["data"][i:i+7]).ljust(8, "\x00")
+            if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(msg)))
+            panda.can_send(tx_addr, msg, bus)
+          tx_frame["done"] = True
 
       if not tx_queue.empty():
         req = tx_queue.get(block=False)
-        # reset rx rx_frame
-        rx_frame = {"size": 0, "data": "", "sent": True}
-        # TODO: support sending more than 7 bytes
-        req = (chr(len(req)) + req).ljust(8, "\x00")
-        if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(req)))
-        panda.can_send(tx_addr, req, bus)
+        # reset rx and tx frames
+        rx_frame = {"size": 0, "data": "", "idx": 0, "done": True}
+        tx_frame = {"size": len(req), "data": req, "idx": 0, "done": False}
+        if tx_frame["size"] < 8:
+          # single frame
+          tx_frame["done"] = True
+          msg = (chr(tx_frame["size"]) + tx_frame["data"]).ljust(8, "\x00")
+          if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(msg)))
+          panda.can_send(tx_addr, msg, bus)
+        else:
+          # first rx_frame
+          tx_frame["done"] = False
+          msg = (struct.pack("!H", 0x1000 | tx_frame["size"]) + tx_frame["data"][:6]).ljust(8, "\x00")
+          if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(msg)))
+          panda.can_send(tx_addr, msg, bus)
       else:
         time.sleep(0.01)
   finally:
@@ -667,10 +698,14 @@ def request_transfer_exit(address):
   can_reader_t.start()
 
   # examples
+  print("tester present ...")
   tester_present(tx_addr)
+  print("extended diagnostic session ...")
+  diagnostic_session_control(tx_addr, SESSION_TYPE.EXTENDED_DIAGNOSTIC)
+  print("application software id ...")
   app_id = read_data_by_identifier(tx_addr, DATA_IDENTIFIER_TYPE.APPLICATION_SOFTWARE_IDENTIFICATION)
   print(app_id)
-  # for i in range(0xF100, 0xFFFF):
+  # for i in range(0xF100, 0xF2FF):
   #   try:
   #     dat = read_data_by_identifier(tx_addr, i)
   #     desc = ""