CEL CODE 71 EGR or Modulator?
 

Hi guys, I am getting a code 71 (EGR) tripping my Check engine light. How do I know if it is the valve or the modulator that needs to be replaced?

thanks

Mark

I have done some additional research but cant find anything that tells me how to know if the EGR Valve or EGR Modulator is what is causing the check engine light.
The EGR valve is a pricey part so I dont want to replace if I dont have to.

Any ideas?