I have this clarification that engine ecu is an emission related ecu because it has components contributing to emission? I have some other ECU in power train, how do i know it is emission related ecu? It depends on the components used in the ECU? Please advise.

 

There are many electronic control units on any motive power unit. Generally speaking, the engine control module will be the one in charge of emissions. There are several inputs and outputs all geared toward proper fuel injection at the optimum time. All other ECUs will be for specific systems which are not directly tied to emissions such as transmission, ABS etc. You can identify theengine ECU quite easily as it is connected directly to everything engine related. The only caveat to that is when you get combined units which then become powertrain control units. You may also find them combined with body control units or all three. Best to check wiring diagram for those.