2000 OBW, 153K. Replaced the knock sensor (with a new OE one) but still get the CEL 325 code. I installed it according to specs as best as I can tell. Is there some other condition that will throw this code?

May be a dumb comment, but IIRC the code doesnt clear its self, did you use a scan tool to reset it manually after replacing the sensor?

Yes I reset it, several times now.

When does the code set? As soon as the engine is started? If it sets the code immediately it's a wiring problem. Check the connector, also check the three large plugs on the bellhousing for tight clean connection.

No, it is not immediate. What plugs on the bellhousing are you describing? Thanks.

He's probably talking about the 2 large plugs (in 2000 it started 2 plugs with the SOHC IIR).

 

On passenger side bell housing near the top. WHere engine meets tranny.

pull it and clean the mating surface of the engine and knock sensor - maybe a piece of debris is between the two.

 

make sure the knock sensor connector didn't get pulled apart on the vehicle/body side harness. sometimes they are about 10x harder to separate than they seem like they should be. if you had to tug on it when removing then you could have pulled the pin out of the harness connector (i've seen it happen before). seems unlikely, but so does your current situation - but maybe it's loose, partially pulled out?

The bolt that attaches the sensor to the block should only be gently snugged tight. Tightening too much will cause the plastic sensor head to crack and break the knock sensor unit. I hope you did not over tighten.