Dear Car Talk:

I have a 1996 Ford Explorer with 164,000 miles. It runs fine, but a year ago, the check engine light came on and indicated a problem with the cam position sensor. The Explorer lives on a very small island with dirt roads and no mechanic. It is driven a maximum of about 40 miles a year, from the marina to our cabin, which we visit once a month or so. After a year with the check engine light on, the Explorer still runs great. Should I worry? -- Peter



No. I'm guessing you retreat to a rustic cabin on a desolate island precisely so you don't have to worry. So don't start now.
 

The sensor probably is bad, Peter. But the effects of a bad cam position sensor are most likely to be felt at high speed. So just don't take any dirt highways on the island.

That sensor helps the computer compare the positions of the cam shafts and the crankshaft. And it uses that information to control the timing of the fuel injectors and the spark.

But, like I said, those things become more critical at higher speeds. And if you're just moseying (and I hope you are) from the marina to your cabin and back, you might never notice any problem at all.

And at worst, if it fails completely, it won't disable the vehicle; it'll put it into a so-called limp-home mode -- which is what it sounds like. You might not even know the difference! In any case, in the worst-case scenario, you'll still be able to limp to the cabin.

At that point, you need to befriend a Ford mechanic, and then invite him to spend a peaceful, bucolic weekend on a secluded island. Then tell him to bring a '96 Explorer cam position sensor with him.