EGR diagnostic switch and function.
I have had the check engine light on when starting the car. That means that the diagnostic switch (it is a bimetal spring that make contact to ground when the temperature is xxxdegrees) has been closed. The EGR valve is ok, the EGR solenoid is ok.
What other purpose has the EGR diagnostic switch other than giing the ECM a signal controling the check engine light.
Jan-Erik





