question about DTC reporting

[TECH89]

My pops had a CEL come up on his Impala. Nothing major as its a p0411 setting for secondary air injection. went throught circuits with test light and TECH2 and all is good. parts need replaced. parts are $400. so my question is when i go the the diagnostics on VCI editor and chose the DTC P0411 it claims its a "no error reported" under the error mode. but it does actually set and CEL. if i spend the $100 to check the box on write the ECM will it eliminate the light? im super confused. is it an emissons thing? dont want to spend $100 for no reason.

[blindsquirrel]

I'm sure you know what year 'his Impala' is, but no one else does. It helps to say exactly what you are working on and post the file.

There is a lot of weirdness in this stuff that most people never run into. Example: 1998 Park Avenue. A/C relay was missing and had P1641 current with the MIL on. Tech2 and the service manual say P1641 is A/C relay ckt. The tune file says P1641 is MIL control ckt. Installing a new A/C relay made the code go away. I think this means GM has it right and HPT is wrong.

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