my sister-in-law's 2009 chevy aveo will not shut off once the key has been turned to the off position and completely removed the ignition. She took it to a mechanic and they couldn't see any issues. Have you heard/seen this issue before? Is this a wiring issue?

 

bad ignition switch?
does the car have an aftermarket remote start?
so the problem wasn't active when the mechanics looked at it?

 

There is no after market starter and the issue was not active during the mechanic's inspection.

 

if the fault is not active, no mechanic will be able to find the fault.

 

Find a wiring diagram . Determine a circuit / fuse that should be " hot " when the car is running .

When the car is acting up , with the ignition off & key out , measure voltage & see if that circuit / fuse is hot .

If it is , I would figure the ignition switch may be bad .

Also , look for a relay that actually " turns on " all the circuits / fuses that should be hot with ignition on . If it has such a relay , it may be sticking closed ?

God bless
Wyr