Reply to Brian W.'s Post: I have a 2002 pt cruiser. The code for P1685 "invalid key recieved from the smartkey immobilizer module" goes off and my car keeps on stalling at 20mph. If I disconnect the battery and let the computer reset the code will go away but a new code of P0403 "exhaust gas recirculation (EGR) solenoid control circuit" goes off. When it does this the cruise control on the car will turn on and off by itself but the car will get up to speed. If I shut the car off and start it up again later the P0403 code will disappear and the P1685 code comes back and the car stalls at 20mph again. Is there any way that these two codes are related somehow since the one goes away when the other goes off.