diff --git a/selfdrive/car/ecu_addrs.py b/selfdrive/car/ecu_addrs.py
index 756cd7f963..0fd4bbd0be 100755
--- a/selfdrive/car/ecu_addrs.py
+++ b/selfdrive/car/ecu_addrs.py
@@ -10,7 +10,7 @@ from openpilot.selfdrive.pandad import can_list_to_can_capnp
 from openpilot.common.swaglog import cloudlog
 
 
-def make_tester_present_msg(addr, bus, subaddr=None):
+def _make_tester_present_msg(addr, bus, subaddr=None):
   dat = [0x02, SERVICE_TYPE.TESTER_PRESENT, 0x0]
   if subaddr is not None:
     dat.insert(0, subaddr)
@@ -19,7 +19,7 @@ def make_tester_present_msg(addr, bus, subaddr=None):
   return make_can_msg(addr, bytes(dat), bus)
 
 
-def is_tester_present_response(msg: capnp.lib.capnp._DynamicStructReader, subaddr: int = None) -> bool:
+def _is_tester_present_response(msg: capnp.lib.capnp._DynamicStructReader, subaddr: int = None) -> bool:
   # ISO-TP messages are always padded to 8 bytes
   # tester present response is always a single frame
   dat_offset = 1 if subaddr is not None else 0
@@ -33,7 +33,7 @@ def is_tester_present_response(msg: capnp.lib.capnp._DynamicStructReader, subadd
   return False
 
 
-def get_all_ecu_addrs(logcan: messaging.SubSocket, sendcan: messaging.PubSocket, bus: int, timeout: float = 1, debug: bool = True) -> set[EcuAddrBusType]:
+def _get_all_ecu_addrs(logcan: messaging.SubSocket, sendcan: messaging.PubSocket, bus: int, timeout: float = 1, debug: bool = True) -> set[EcuAddrBusType]:
   addr_list = [0x700 + i for i in range(256)] + [0x18da00f1 + (i << 8) for i in range(256)]
   queries: set[EcuAddrBusType] = {(addr, None, bus) for addr in addr_list}
   responses = queries
@@ -44,7 +44,7 @@ def get_ecu_addrs(logcan: messaging.SubSocket, sendcan: messaging.PubSocket, que
                   responses: set[EcuAddrBusType], timeout: float = 1, debug: bool = False) -> set[EcuAddrBusType]:
   ecu_responses: set[EcuAddrBusType] = set()  # set((addr, subaddr, bus),)
   try:
-    msgs = [make_tester_present_msg(addr, bus, subaddr) for addr, subaddr, bus in queries]
+    msgs = [_make_tester_present_msg(addr, bus, subaddr) for addr, subaddr, bus in queries]
 
     messaging.drain_sock_raw(logcan)
     sendcan.send(can_list_to_can_capnp(msgs, msgtype='sendcan'))
@@ -58,7 +58,7 @@ def get_ecu_addrs(logcan: messaging.SubSocket, sendcan: messaging.PubSocket, que
             continue
 
           subaddr = None if (msg.address, None, msg.src) in responses else msg.dat[0]
-          if (msg.address, subaddr, msg.src) in responses and is_tester_present_response(msg, subaddr):
+          if (msg.address, subaddr, msg.src) in responses and _is_tester_present_response(msg, subaddr):
             if debug:
               print(f"CAN-RX: {hex(msg.address)} - 0x{bytes.hex(msg.dat)}")
               if (msg.address, subaddr, msg.src) in ecu_responses:
@@ -94,7 +94,7 @@ if __name__ == "__main__":
   set_obd_multiplexing(params, not args.no_obd)
 
   print("Getting ECU addresses ...")
-  ecu_addrs = get_all_ecu_addrs(logcan, sendcan, args.bus, args.timeout, debug=args.debug)
+  ecu_addrs = _get_all_ecu_addrs(logcan, sendcan, args.bus, args.timeout, debug=args.debug)
 
   print()
   print("Found ECUs on rx addresses:")