Hi People,
Had to change my knock sensor out today due to it being faulty and producing an engine check light. This is an easy DIY that all up takes about 25-30 mins and can be done by anyone competent enough to service their own car.

A good time to do it to prevent failure is when removing intercooler to replace split factory y pipes etc as if these are split its a good indication that the knock sensor is probably quite old as well. Other then that replacing it when timing belt service interval is up is probably a good time to do it.

I did this on my RS that has a RS manifold and water to air intercooler but the location is the same for the WRX or STI ej205 and 207s .

Tools needed are
. 12mm socket on long extension with ratchet
. medium flat head screwdriver
. Lead light or work light of some kind
. guard cover so you don't scratch your fender ( can use old towel )
. Magnetic parts tray or box to put removed bolts etc in .

Part needed
. New genuine Knock sensor part #22060AA031 cost $14 - $35 depending where bought.


.First up let car cool as its much more comfortable . I disconnected the negative terminal on the battery as well seeming we are changing a component of the engine management system.

. Remove intercooler from engine . If you have a front mount you will probably have to remove the piping from the throttle body to first join.


.Once the intercooler is out of the way directly below the throttle body is a white plug with a single wire that needs to be disconnected and popped off its bracket , this connects the sensor. As per pic below.
.

. Now you need to take your 12 mm socket on the long extension and undo the bolt through the center of the sensor located on the passengers side of the throttle body on the top of the block as per pic below.


. The knock sensor should now come free and be swapped with shiny new un cracked one . Old sensor as per pic below.


. Be sure not to over tighten new sensor and I used some medium strength thread locker on the bolt. Once sensor is bolted in place reattach new sensor plug to bracket and plug in.

. The intercooler can now be replaced and all hoses and brackets double checked for tightness.

. The last step is to reconnect the negative terminal of the battery then if running a factory ecu you need to reset it . I followed Rosscos ecu resetting guide that can be found under search.

Hope this helps and is only a guide do any of this at your own risk.

Also helps if you use a bit of bluetack on the socket, I had mine out about 5 times in a week and got I it down to about 15min for complete replacement inc top mount on and off ......... it turned out to be my AFM plug in the end grrrrrrrrrrr

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Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.