I have an '03 G35 with about 65,000 miles. From perusing this forum and other internet sources, it seems that the camshaft and crankshaft sensors going bad is a common problem as theses cars age, often leaving drivers stranded, sometimes in dangerous traffic.

Do you think it makes sense to have the sensors replaced as a preventive measure? Some reports on RepairPal indicate that sometimes the problem recurred soon after replacement (although most reports seem to indicate that replacing one or both sets of sensors fixed the problem permanently). I don't want to make a currently nonexistant problem worse!

 

It doesn't really work like that; and anyone stranded on the fwy most likely let the warning signs go too long. The car usually acts really funny long before you even get a code. It starts "hiccuping" at full speed where it feels like you let off the gas even tho you didn't. I've only had one cam sensor go out and that was at 155k miles, so you may have plenty of time.

If you just want a sense of security tho, you could keep new ones in the car with you. Then maybe take out the old ones and put them back in just to get familiar with the process. You could easily do it in a few minutes on the side of the road if you know how. I believe you just need a 10mm wrench. There's one in your trunk by the jack.

 

Most auto parts stores carry our sensors, so help would be 30 minutes or less away. I wouldn't replace prematurely, but I would highly recommend carrying around some for a long trip. As a daily driver only, meh on pre-purchasing or preparing.

 

Only issue I've had with mine was the cheap after market one the used car dealer put in before I bought it.