The cam sensor interrupter (magnet) may become demagnetized and/or fall off of the camshaft gear causing the Check Engine Light (Service Engine Soon) light to illuminate. On higher mileage vehicles it would be advisable to replace the timing chain and gears if this problem were to occur as the timing cover must be removed to replace the interrupter.
Car Problem Reports
Buick LeSabre Check Engine Light Due to Cam Sensor Interrupter Falling off Camshaft Gear
Buick LeSabre Problem
Visitor, 1992 Buick LeSabre, 198,480 mi
my check engine light stayed on every time i got the cam sensor replaced. i took it to an electrican come to find out they had to replace the timing belt to ened up costing me 450 dollars to fix the problem