Dealership claims rats chewed through the knock sensor wire harness, and I'm just curious what this part is actually doing?
The knock sensor is used to control engine timing as well as fuel mixture. Under the right acceleration conditions the engine needs to be about 1/2 a degree advanced from the point at which knock (ping) occurs. The knock sensor helps the ECM know where that point is.
The sensor wires transmit the signal back to the engines computer, and if an engine knock (caused by a too lean condition) is detected, it will tell the fuel system to enrich it self, by added more fuel. and this saves the engine from damage.
