Car's check engine light popped up and OD light was flashing. I know zilch about cars so I took it to the mechanic

My mechanic said that my ECM was bad, gave me the number and I bought a replacement off ebay (89661-33430). He said it was a pretty simple swap just make sure the battery was disconnected.

Swapped it out hooked the battery up......check engine light and the OD light are back after driving for 5 minutes. Anything else I needed to do besides the swap?

 

Get the engine light codes first?

 

Fuel Trim Malfunction Bank 1 P0170

Manufacturer Control Transmission P1705

 

I am currently dealing with the same code P0170 fuel Trim. It has been to the shop several times, and I eventually asked the mechanic for the list of possible fixes: I had already replaced the ECM, plugs, coils packs, fuel filter, fuel pump, Mass airflow sensor, injectors, and vacuum hoses. I currently have it in the shop to have the electronics checked. It very well maybe that one of the replacement parts may have been bad as well, I will update this post once I get it out the shop.