SWITCH is actually codeword that the ECU uses to check it systems and functions. There are a lot of codewords/switches. For every sensor or system that the ECU monitors or not there is a specific codeword.

If the EGR codeword is set to 0 the ECU will not monitor that function or engine parts connected with that function. Changing any map or deleting error codes is not monitored regarding EGR function.


Intake port shut-off valve (picture attached) is the valve that closes when you turn off the engine. It stops the air entering the engine and that results in quicker and smoother shutting down. It is located in front of the EGR and it is where the intercooler pipe conects to the intake manifold.

Thanks got it. It sounded strange to me but it is ok now. So, wrapping up, if my understandong is right: I can switch off the EGR specific bit and this does NOT have any effect on the shut-off valve. The ECU is simply NOT monitoring anymore the EGR function. As a consequence it does not matter if the EGR map is flattened or not. This does not lead to a DTC fault signal.
If this is correct I will go back to the map to switch off the EGR ECU function.
I just need to be sure that the bit to zero in this ECU/Software version is located at 71FEA address.
Actually I do not have any problem with the mapping for the car as this is an old car I am playing with, but definitely help me to better understand how things work.
Thank You.