Key won't work all of sudden - 2005 GMC Yukon

Connect it to a code reader scan tool. The engine light codes will tell you some of the reason, but Jeff's answer is far better than mine regarding how all this stuff works..

Go on youtube and put in how to reset your car key after renewing key fob battery good luck colin

Check connection battery,could be starter.

ignition keylock cylinder broken or could have the wrong ignition key.

So you can hear the fuel pump run when you turn the key on

May have to hold a long screw driver to tank & your ear & have
someone cycle the key

Have you checked fuel pressure?

If your not the only person going to work on this vehicle
& are going to a repair shop,then it doesn't really matter
what the issue is eg: do you have any knowledge about cars?

You may want to try to slightly push / pull your vehicle to take weight / tension off the transmission, which in turn will allow you to turn the steering wheel enough to see if the ignition switch can be turned.

Try starting in neutral. Gear sensor may be heating up and not registering park.

electronic key on 2008 jeep cherokee says key damaged or key not programmed. car won't start. some things work but radio won't come on. etc..

you might want to spray the key hole with wd40 and keep trying your key both ways,they sometimes get dry and don't work or maybe even frozen.

weird this one, has a transistor playing up but where ??