Hi guys, I have a 1995 WRX and the CEL came on this morning. I have checked the code and it is 22 which is the knock sensor. I am fairly new to scoobies and have limited knowledge of them.

Firstly, what is a knock senor and what does it do?
And
Secondly, what has caused this?

The car currently mis-fire's over 4500-5000rpm when I'm thrashing it and for this reason I am changing the coil packs this weekend to overcome that problem hopefully! The plugs, oil and oil filter have just been done recently. Any ideas???

Please help!!
Thanks

 

a knock sensor detects pinking and will then tell ecu to adjust ignition timing accordingly as for what has caused it could be a straight forward faulty sensor or you mentioned a misfire get that fixed first and see how it goes could be that detecting knock due to the misfire and adjusting timing is not stopping it so throws up knock sensor fault