Hey,

 

I have a 97 legacy outback 2.5 auto with a CEL. I had the code read, replaced knock sensor. Light went off for 3 days and is now back on. The car has 87,000 miles on it and was running really nicely with the new sensor. This is super disappointing. Any advice for investigating the cause of the problem would be great.

Thanks, Dave

Hey,

 

I have a 97 legacy outback 2.5 auto with a CEL. I had the code read, replaced knock sensor. Light went off for 3 days and is now back on. The car has 87,000 miles on it and was running really nicely with the new sensor. This is super disappointing. Any advice for investigating the cause of the problem would be great.

Thanks, Dave

 

what code are you getting now. Do you hear nay noises out of the front of the engine, like a tensioner making noise or more piston slap then usual? Any accessory drive noises?

Where did you get the knock sensor from?

 

nipper

And what was the actual P0xxx or P1xxx code you read?

I'm taking the car back to have the code read tommorow. I'm hearing what sounds like piston slap on start-up. I goes away as the engine warms up to operating temp. I've read that a rattling heat shield can cause the sensor to detect engine knock? Mine's rattling away so ill do that and see what happens.

 

If I remove the timing belt cover would I be able to see a loose tensioner? Thanks for the replies

 

Dave

more piston slap then usual?

 

I cant be the only person who finds that funny. Im sure piston slap is a bad thing. Are Subarus more prone to it because of their short fat bore?

make sure the knock sensor connector and wiring is good.

I cant be the only person who finds that funny. Im sure piston slap is a bad thing. Are Subarus more prone to it because of their short fat bore?

all engines of this vintage have it to some degree, well 4 and 6's. They reduced the piston skirt for emissions and HP gains. This cause slap, as the skirt would hold the piston straight.

 

nipper

I had the same problem. I replaced the sensor. The check engine light came on again (codes: misfire, and fuel sending unit). Anyway, some rattling and knocking started, and got louder. Turns out my timing belt pulleys and tensioner were wobbling and the belt was making a racket against the cover. I'm having the pulleys, tensioner and timing belt replaced (and the water pump, wobbling too). The wierd thing is that all that racket didn't make the check engine light come on. Go figure! But at 180,000k I figure now's a good time to do the timing belt.