P0401 after HG replacement?

[Big Jimbo]

I just got my LX450 back together after the HG blew. I replaced every rubber hose and tube on the intake manifold. If I drive over 60 MPH the engine light comes on and it is P0401 on the reader at Auto Zone. I double checked all the hose connections. Could the Vac Modulator have gone bad at the same time as the HG blew? Could sucking up all that white exaust with the antifreeze in it messed something else up?
Boy, I thought I had it all fixed.
I replaced the rear main and sealed the pan arch and that doesn't leak yet!

 

[Big Jimbo]

I found the problem! I was going to remove the temp sensor and when I unpluged it I noticed that one of the two prongs in the male side had pushed out of the plug when I had connected it during my reassembly. I fixed the plug and now it works! Too bad for me (but good for C Dan) I had already replaced the vac modulator.