Shock sensor and cold start

I had a new shock sensor installed, check engine light identified that. There was a new sensor installed at great expense, and then reworked with timing belt and water pump. It works fine, but when its a cold start, it still sends a shock sensor code (52 I think) wait five minutes, start it again...no code. Good for the day.Ive had a shop check it several times and I think they just don't know, or won't take responsibility for figure it out. I get it, its way in there, tough to get to, I know the guy put in a new one, but maybe it was after market part...any thoughts?