Code 18

[93buicklesabrelmtd]

Service Engine Light came on yesterday when I started the car.
It never comes on!
So I checked it immediatley. It gave my a code 12 first then code 18. Then started the loop over again.

My question is what do I need to look at or for?
Code 18 says: Cam/Crank Error

But im thinkin if I had a bad cam wouldnt it give me code 41: Cam Sensor Circuit

Im not sure, what should I look for and where at?
I truned car off and restart and it never gave the code again!

But that same time it set the code, the car did start up a little different!!!

93 Lesabre

[maxwedge]

41 would be no cam sensor signal, 18 is the comparison between the signals from the crank and cam sensor. Something is not in synch, the magnet is usually the problem on cam gear for a cam sensor problem, but the signal from the crank sensor make be erratic or weak. Checking this out requires a scope to really see the signal.