new fuel pump, fuel filter, and now the check engine light is on. Help???

I just had a new fuel pump and fuel filter replaced on my 2005 Chevy Malibu after the fuel pump went out coming home from vacation and 4 hours from my home. The gas tank had to be dropped and the tank was full of bad gas. They emptied and clean the tank, replaced the fuel pump and fuel filter and cleaned the injectors. On the way home from the repair shop the check engine light came on? What now? I check the gas cap lid and tightened it. Help???

You might call the shop, that did the work, tell them what happened. See if they have any ideas. You might look, around the tank, see if they left any wires disconnected.

Some national brand auto-stores will read codes free of charge. Have them check for codes.

find out what the codes are before you get excited about what it is, then you can determine if either the shop made a mistake, a faulty new part, or something else has gone wrong.