1990 oldes 98 Regacy

A friend of mine is getting a code 41 on his oldes. Guess its suppose to be the cam sensor, is this a job you take to the garage or do yourself? I've never worked on an Oldes and I've heard the cam sensor can be a bitch. Any input would be greatly appreciated.

The magnet on the cam gear may have fallen off, the most common problem or the chain and gears are worn, the front cover has to come off to get to these parts.