We have two keys for this car, and both of them used to work fine until this week (mechanically, not remotely).
Now, when one of them is inserted, the green key-light turns on the dashboard... It can still open the doors, but it can no longer start the ignition. The second key works fine.
Answers here and here talk about an immobilizer problem, but if that was what happened to us too, both keys would've stopped working, wouldn't they have?
What's happening and what do we do?
Its extremely rare the immobilizers memory only corrupts one key so its more likely a fault with the key it self.
Its not uncommon for the remote head keys to fail. Its usually from moisture getting inside. If it is a remote head key you can attempt to open it and see if it has built up corrosion. If so clean it away with isopropyl alcohol and it may start to work again. Also be sure to check the antenna on the key fobs pcb to see if the soldering is loose or cracked. It will be a long black rectangle device with or without exposed copper winding.
The transponders in non-remote keys very rarely fail but it does happen once in awhile.
I have also run into cases where the memory in the transponder itself was corrupted/rewritten, so it may can just be reprogrammed.
Other then that you can call a good local locksmith to come check it all out for you and replace if necessary. Avoid the paid listings on google.
