Knock sensor question...

[86GLScooby]

Hey Guys, hope you are all doing well.

 

I have a 97 Legacy GT wagon and the other day I noticed that my check engine light was on. I took note and then the next morning when I started my car it was off again. Today I drove into town and after 20 or so miles I smelled a chemical smell, it smelled like epoxy, kind of burning smell coming from under the hood. I noticed that the check engine light was on again and since I was right by an advance auto zone I had them read the code. It was the knock sensor code... I let the car cool down not knowing what in the engine could cause that smell, did laundry and had some food... when I restarted the car, the light was off again and it stayed off all the way back home, 20 miles going 35 mph...

 

I just read a whole bunch of info on the knock sensor. What I don't understand is how do I know if replacing it would fix the reason it is being triggered? It's a sensor, doesn't it tell me when something is wrong in my engine, not that there is something wrong with the sensor?

 

This might not be related, although it would be a big coincidence... for the first time since I replaced my head gaskets last year and did a lot of work to my subie (thanks again for all who helped me, that was quit the project) I put in cheap fuel from Walmart and not Shell fuel. My check engine light came on close to the end of the tank being run out... Could it be bad fuel?

 

Now, should I use a fuel cleaner or seafoam to see if that fixes the problem before I go and replace the sensor?

 

I appreciate your input and help,

Thanks all and keep cool out there, this heat is dangerous...

[Fairtax4me]

Knock sensor is a very common failure and is a well covered topic here. The sensors most common cause for failure is due to corrosion. The code can also be set if the wiring to the sensor is damaged. An engine condition will not cause a knock sensor code to be set. Failure of the sensor or wiring to it is the only reason a code wil be set.

 

The burning smell is not an indicator of a bad sensor, more than likely that is oil or some other fluid, axle grease maybe, burning off of the exhaust and is unrelated.

 

Replace the knock sensor and inspect the wiring to it for damage. eBay is a good source for inexpensive sensors, one member just posted that he got one for less than $15 shipped and it worked great.