I have just completed my second 2.2 conversion. Both engines came from 97 model cars. The first swap was to put a 2.2 from a 97 legacy L into a 96 LSi.

My most recent was to swap a 97 2.2 impreza outback engine into my 97 legacy outback.

After both swaps I have a check engine light indicating "knock sensor". Both were 2.5 to 2.2 conversions. I find it odd that both engines might have came with a bad knock sensor. Is this common? Did I miss something that I needed to do on my swap to prevent the CEL?

Both engines seem to run fine. I am sure there was no CEL on in the 97 Legacy outback before the swap.

Did you remove or unplug the sensor for any reason

 

I would first make sure the sensor is plugged in and the pins didnt back out of the connector. Next double check the large 16 and 12 pin connectors on the bellhousing. Make sure theyre plugged in tight and the pins are all connected.

Very common to see knock sensor failures - the casing crack. I've done dozens of 2.2 swaps and it's come up on maybe one or two. You are just unlucky with knock sensors. I always choose whichever one looks better when I'm installing the engine.

 

GD

Last year I had a used '95, 2.2 installed in my 98 OBW, after wife cooked the original 2.5 that came with the car. The shop installed the 2.2 with no knock sensor issue, so I guess it is a simple plug and play.

 

Suggest you replace the knock sensor, be careful not to tighten the bolt very tight, or you will crack the plastic casing around the knock sensor.

the knock sensors fail all the time. remove it and it'll be cracked at the base.

 

also if it's ever been messed with it's not hard for the pin to pull right out of the connector and the connector to be compromised/not seating right.

 

there's a very specific technique to installing them, directions are posted on threads here. connector is supposed to be installed at a certain angle and torqued properly. i've never seen that alone cause a check engine light though but if everything else checks out...

any uses for 50 bad knock sensers see many failed

I have not disconnected the knock sensor or otherwise tampered with it. Are the 2.2 and 2.5 sensors interchangeable? it seems local parts suppliers list a different part number, and seems that the maybe the plug is different? Is it possible to splice the 2.2 connector onto the 2.5 knock sensor? I know at least the 2.5 sensor from my most recent swap is good. Right now I have more time than money to invest. If I can fix it with existing parts I already have, I would prefer to do that due to budget restrictions I currently have.

They're all one wire units. Just swap the plug if you need to. It's not hard to slide the pins out.