Check Engine Light

[PiTTdAwG72]

When I bought my 87 runner the guy told me the check engine light was on due to a bad knock sensor. I have no experince with a knock sensor was hoping you guys can tell me if it makes sense.

The light only comes on once the motor hits 2K rpm and then stays on until I shut the motor off. The motor is running fine and Im getting a little over 20 mpg.

Does this sound like its a knock sensor? And if so if I replace it should I notice a difference in how it runs, or my mpg?

Im just trying to decide if its worth replacing, the guy I bought it from said its a spendy part.

 

[BucknutBob]

You should have a code stored in the computer for it. Grab a manual and do the check procedure--usually just shorting a wire across two pins on the diagnostic port, then count the flashes of your light, compare with a code chart, and that should tell you if the sensor is goofy. Just about every sensor is kinda spendy, but you should replace it if it's bad--the knock sensor will protect your engine from expensive internal damage.