I never heard of EGR problems with the Prius,had a 2006 2nd Gen that had just under 600,000kms when i got rid of it and my current 2011 Gen 3 has 355,000kms....i was a bit OTT with maintenance on my 06...s'pose i am with my current yoke...i would advise cleaning the fan that draws air to cool the battery pack.