Chucky357

Hello I have a 2007 rx i have had it for about 8-9 months ran great was driving on the highway at night I seen steam coming from the top of the engine looked at my gauge and it was all the way down to the cold pulled over as fast as I could and shut it off went to look at the engine and the small hose by the filler broke off and on the front of the radiator were the filler is had a crack about 2 in long and it looked like it had been patched I checked my codes and I have a few about cylinder misfire and heat sencer does that sound like a blown gasket to you im freaking out man thank you.

Leeper

There's several ways to check for blown head gaskets, if you did overhead the engine enough to blow the head gasket at the very least it is likely you'd need to have the head checked for warping too

Felix

Seems like you'll need to change out the temp sensor as the gauge wasn't reading. IDK for how long the gauge wasn't reading? Is there any coolant in the oil or oil in the coolant? I'd also be looking to swap out the radiator soon as well.

Vincenze

Happened to me in France. Had to drive on Hybrid back to village. Massive overheat and steam blow from hairline crack. Just got engine off asap.

The 400 is quite a hardy block. You may have misfires during the emergency. Things may straighten out with new radiator, code clears. Hoping no damage for you