I noticed a sensor on the driver's side of my engine that looks like it is leaking oil. It is located just above the top spark plug towards the front of the car, and it has a wire coming off of it. Does anyone know what it is? I've looked through the parts catalog and factory manual and haven't been able to find it.

Thanks,
-Charlie

 

That is the knock sensor. When the knock sensor is bad it will pick up a lot more "knock" since all the insulation material has been melted. This will force it to retard the timing. It costs ~$170 for a new one, though, Malloy Mazda might have it for quite a bit less.

 

mine "drips" a little bit too, does that mean i'm seeing timing retard as well?

 

It means it's getting more sensitive, but that doens't necessarily mean you are getting any timing retardation yet.

The "goo" basically muffles the sounds to the sensor. When it melts/leaks out, the sensor is exposed and the reading will be higher than the stock ECU is expecting.