sheipe05 Posted January 15, 2006 Share Posted January 15, 2006 I just bought an '01 Legacy a few months ago. I noticed a slight knocking sound especially when the engine is cold. I read a little about people having "piston slap" and replaced the pistons. Others say it's normal and the noise goes away when the engine warms up as the pistons expand. I didn't think much of it until my check engine light came on. it gives me a knock sensor error. Has anyone heard anything on this issue? Quote Link to comment Share on other sites More sharing options...
Setright Posted January 15, 2006 Share Posted January 15, 2006 If it's a slight metallic rasp that eases off as the engine heats, it's ok. Sounds a bit like a Diesel engine. The knock sensor code is probably just co-incidence. Check the one you have now, if the connector on the wire is gray, it's the old type and needs replacing anyway. Quote Link to comment Share on other sites More sharing options...
sheipe05 Posted January 15, 2006 Author Share Posted January 15, 2006 it sounds more like a knock than a lifter tap. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 16, 2006 Share Posted January 16, 2006 It would be more unusual if you had a 2001 that did not slap until warm. Most of them do including my own phase 2. I was able to cut it down a bit with Mobil 1 15-50 which might not be a winener in cold climates. Most manufacturers are having piston slap problems from shortening the skirts to meet EPA regulations. Don't feel like the Lone Ranger out there. A friend's Honda makes mine look quiet. Knock sensors are fairly cheap and extemely common failure points. Not just on Subies either, I just changed one on a BMW. It gives you the code for a reason, the car is asking for a knock sensor so be a kind owner and give it one. Quote Link to comment Share on other sites More sharing options...
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