this should work

common/params.cc

@@ -114,6 +114,7 @@ std::unordered_map<std::string, uint32_t> keys = {
     {"FirmwareQueryDone", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
     {"ObdMultiplexingRequested", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
     {"ObdMultiplexingEnabled", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
+    {"ObdMultiplexingSet", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
     {"ForcePowerDown", CLEAR_ON_MANAGER_START},
     {"GitBranch", PERSISTENT},
     {"GitCommit", PERSISTENT},
@@ -157,7 +158,7 @@ std::unordered_map<std::string, uint32_t> keys = {
     {"NavSettingTime24h", PERSISTENT},
     {"NavSettingLeftSide", PERSISTENT},
     {"NavdRender", PERSISTENT},
-    {"ObdMultiplexingDisabled", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
+//    {"ObdMultiplexingDisabled", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_ON},
     {"OpenpilotEnabledToggle", PERSISTENT},
     {"PandaHeartbeatLost", CLEAR_ON_MANAGER_START | CLEAR_ON_IGNITION_OFF},
     {"PandaSignatures", CLEAR_ON_MANAGER_START},

selfdrive/boardd/boardd.cc

@@ -128,15 +128,13 @@ bool safety_setter_thread(std::vector<Panda *> pandas) {
     }
 
     bool obd_multiplexing_requested = p.getBool("ObdMultiplexingRequested");
-//    std::string obd_multiplexing_requested = p.get("ObdMultiplexingRequested");
-//    if (!obd_multiplexing_requested.isEmpty()) {
     if (obd_multiplexing_requested != p.getBool("ObdMultiplexingEnabled")) {
       const uint16_t safety_param = obd_multiplexing_requested ? 0U : 1U;
       for (int i = 0; i < pandas.size(); i++) {
         pandas[i]->set_safety_model(cereal::CarParams::SafetyModel::ELM327, safety_param);
       }
-//      p.remove("ObdMultiplexingRequested", obd_multiplexing_requested);
       p.putBool("ObdMultiplexingEnabled", obd_multiplexing_requested);
+      p.putBool("ObdMultiplexingChanged", true);
     }
 
     if (p.getBool("FirmwareQueryDone")) {

selfdrive/car/fw_versions.py

@@ -236,10 +236,9 @@ def get_fw_versions_ordered(logcan, sendcan, ecu_rx_addrs, timeout=0.1, num_pand
 def set_obd_multiplexing(params: Params, obd_multiplexing: bool):
   if params.get_bool("ObdMultiplexingEnabled") != obd_multiplexing:
     cloudlog.warning(f"Setting OBD multiplexing to {obd_multiplexing}")
-    # Remove response param that boardd writes to block on it
+    params.remove("ObdMultiplexingChanged")
-    params.remove("ObdMultiplexingEnabled")
     params.put_bool("ObdMultiplexingRequested", obd_multiplexing)
-    params.get_bool("ObdMultiplexingEnabled", block=True)
+    params.get_bool("ObdMultiplexingChanged", block=True)
     cloudlog.warning(f"OBD multiplexing set successfully")