Knock Sensor Replacement

[1991legacyturbo]

What are the procedures for replacing the knock sensor? i am also getting a code for a "can purge thing"???? how and where do i get one of those?

[Buffman]

knock senor is pretty straightforward. Not sure if on the turbo models they are in the same location but on my N/A it's on the back of the block driver's side by the intake manifold. IIRC 12mm bolt holds it on Super easy.

[ciper]

What are the procedures for replacing the knock sensor?

Unplug old sensor
Unbolt old sensor
*Optional - use sandpaper to clean mating surfaces
Bolt new sensor on
Plug senor in
Drive away.

[altron23]

all subaru knock sensors are in the exact same place so far, super easy to do, easiest 1hr to get at work when flat rate!

[1991legacyturbo]

hey thanks guys. do i have to drain my coolant to do this?

[kleinkid]

The knock sensor has nothing to do with coolant. It simply bolts to a threaded, dead end, hole in the block. Make sure you are getting ready to remove the knock sensor and not the coolant temp sensor.

[Buffman]

some engines have the knock sensors thread into the block into a coolant passage. it's that way on my LT1. Maybe he assumed that was the case.

[1991legacyturbo]

ok thanks guys. the reason i thought you had to drain the coolant was because my hanes manual said something about draining the system.



The purge cannister solenoid??? where do i find these and how hard are they to replace?

[93Leg-c]

When replacing the knock sensor, the fsm says to install the sensor with the wire going out at a 45* angle. This means if the passenger compartment is 12 o'clock and toward the radiator is 6 o'clock, the wiring coming out of the installed sensor should be at the 10:30 position.

I don't know the technicals as to why the fsm says that but here's what happened to me: I installed a new OEM knock sensor with the wire coming out at the 2:00 position because it was easier to connect the male and female plugs together. But my engine kept pinging and sometimes knocking. I read the fsm and followed the instructions for the 45* angle wire placement and the pinging and knocking went away.

[kimokalihi]

Took me all of 2 minutes...maybe 1.

[Bosco]

The cansiter purge solenoid is tricky to get to. if you know where it is, you can try to get at it.
I, along with a few others, have just left the bad one in place and plugged the 2 vacum lines and the wiring clip in to another sensor and found a place to put it. It can be a real pain to get to in it's stock location. (Under the intake runner behind the PS pump)
Replace it, and reset the ecu (possibly not necessary).
if you do a search, you will find a thread entitled "canister purge solenoid - fixing the problem" it has a nice picture of what it looks like if you're unsure.

[codfizzle]

I was getting the same code, and you know what the problem was? My gas cap vent was plugged. It was building up too much back-pressure in the fuel system and throwing a code 35. As soon as I would take the gas cap off and release the pressure, the CEL would turn off.