I agree that it sounds like you blew the sensor loose with the water pressure.
However; if you think the tow charge is a huge expense, you ain't seen nothing if the engine goes oil starved.
I'd play around a bit in the garage and see if you can locate the sensor- May be a wiggle of a wire fixes your problem. If no, I think I'd tow- No questions asked- it's cheap insurance.
Dinan stage 1
"Good, bad...I'm the guy with the gun"