Is the deaer fixing my car or just clearing the check engine light?

Question

I bought my car 10 days ago the engine light came on the day after leaving the dealer / mechanic shop. The day after the light came on, my car wouldn't start He said he replaced the entire electrical system. He had my car for7 days. I picked it up and again within 1 day THE check engine light came on yesty for the 2nd time. Both times the engine light came on excatly 1 day (24hours)AFTER leaving the dealership and being PROMISED its safe and reliable??? the code is coming up P0491 and just so happens 1 of the possible causes is they electric harness(the same problem he claimed to have fixed) sounds fishy huh any suggestions??????