The famous warning that says not to keep the cellphone in the front pocket, or it will affect your "jewels" may or may not be true, but the new warning about cellphones disabling car keys is unfortunately a proven fact.

The car manufacturer Nissan North America has issued a warning for some of its customers, not to keep the car keys too close to the cellphones, or the key will jam and they'll be left admiring their new, shiny car that won't start.

For now, only the "proud" owners of two of the most luxurious sedans, available on the North American market, have this problem and they will have to keep the two devices at least an inch apart to avoid disabling the "intelligent keys." They are the 2007 Nissan Altima and Infiniti G35 sedans, two of the top-selling models.

These intelligent applications, called I-Keys, are wireless portable keys that allow you to start your car by simply pressing a button, when the on-board computer detects the wireless transmitted signals from the key.

Very clever, so far. The only thing that's not so intelligent about the I-Keys is the fact that signals from the cellphone can erase the electronic code on the keys, rendering them unable to unlock or start the cars.

"We discovered that if the I-Key touches a cellphone, outgoing or incoming calls have the potential to alter the electronic code inside the I-Key," Nissan spokesman Kyle Bazemore said. "The car won't start and the I-Key cannot be reprogrammed."

Intelligent keys are a recent and very useful development in the car industry, allowing the owner to carry an electronic key or card in his pocket, which sends wireless signals to the car when he is in a few feet, automatically locking and unlocking the doors and replacing the old key contact with a start button.

The faulty keys will be replaced and all current owners have been notified about the problem to visit the dealers and get new keys, in case they encounter the problem.