Electrical parts are not returnable unless it ' s defective . You buy it , you own it . The reason for this is because if you had a short and install new part then that new part is damaged , or it is now a used part . Part stores couldn ' t stay in business with broken or used parts on the shelf . Used PCM ' s are usually nonrefundable too and can cost $ 175 or more to program . You agreed to order it or pay for it , it ' s your part now . It ' s also your car . The tech does the diagnostics , what else could he do ! Can ' t swap these sort of parts around . As for CEL after alternator repair , shit happens . It ' s your car so you fix it . Replacing an alternator doesn ' t make it a new car . Those cars have a shitload of problems .