code 41

I have an 89 olds 98 regency broughm. The check engine light is on. Car runs fine. Checked codes-- showing 41--replaced cam sensor last year, checked connectors-wiring- and voltages--all checked out o.k.-- Today I tried swapping out the computer--retested codes--still get 41--cleared codes and rechecked--keeps comming up with 41. Need to smog soon. Could use some help what to check next.
Willy Ray