i've done some research on vehicle speed sensor and knock sensor.i know the vehicle speed sensor controls the speedometer and i have all the symptoms of a faulty vss with speedometer not metering speed,and only working when it feels like it.my question is how easy is it to replace this vss? i have knowledge of electricity mechanicle ability.
now the knock sensor i know it has something to do with engine knocking.what i want to know is what long term damage can take place if i dont have it replaced right away if it is bad? also how hard is it to replace it yourself?

anyone know the prices of these sensors?any info will be appreciated thank you.

 

I have had these sensors goin off for a while now. I caved in and took it to the dealer who said replace the battery. Of course the $70 initial diagnostic cost went towards my brand new (and REALLY expensive) nissan battery. So that solved that problem for like 1 week and great it goes on again. Can anyone help. Someitmes i get teh automatic transmission control unit signal to the ECU. Is there some electrical problem that ties in to all these?