When replacing crank shaft sensor, do you need to replace the starter

Had the crank sensor replaced by Pep Boys, worked three weeks, then problem began again. Returned to Pep Boys, who told me the computer needed to be relearned. Computer relearned, worked for two weeks. Dealer said after market crank sensor needed to be replaced; also after-market starter (had for 1.5 years) had to be replaced as well.