[2010rav]

I just cleaned my throttle body due to a constant high idle around 1500 rpm and disconnected the battery while doing it just to clear the memory. After buttoning everything back up the idle after warm up is now down too about 1100 rpm but i noticed when the car is off the tach only drops to 500 rpm as if the engine is still on. Any suggestions? This is a completely stock 2010 4cyl rav4.

 

[whipaway]

If you disconnect the battery, will the tach drop to zero?

If so, then the battery disconnect/connect action could have caused some sort of spike in the electrical system and damaged an op-amp or other circuit that drives the tach, and a low-level signal is constantly being fed into it, causing it to register.

If not, it might be some sort of mechanical issue not allowing the needle to return to zero.