Thanks for the question.
Your problem is most likely due to a faulty passlock sensor, also known as the ignition lock cylinder. The sensor is built into the sensor and requires replacement of the entire lock cylinder.
Something you can try...
Attempt to start the car (it will not start), release the key and leave it in the ON position for 10-15 minutes or until the security lamp turns off, turn the car off for 30 seconds. Then attempt to start the car. This procedure may need to be perform up to 3 times. Either way, the lock cylinder will probably need to be replaced.
Here is a picture of the lock cylinder, so you know what the part looks like...
I hope this helps,
Thanks,
Travis
Yes, leave the key on even if the car stalls out.
The cost of the part is about $290 and can take about 1.5 hours for the repair.
P&ontiac Technician
7+ years of GM dealership experience, GM ASEP trained, Assoc. Degree in Auto. Tech.