2012 Lexus CT200H - 111K
The EGR system doesn't necessarily need to be serviced unless it throws a specific code or has actual poor gas mileage. The forums are full of alarming posts, but also full of information that is not entirely accurate. You can tell a lot about the health of hybrids by the mpg. Go fill up your car and get on the highway. Drive with cruise control set at 65 for about 50 to 100 miles. If you are getting less than 40 mpg, chances are the system is clogged (but not clogged enough to throw a code if you have no code). Getting less than 40 around town doing short trips does not count. I usually get less than 40 doing short trips around town, but I recently did a road trip from California to Arizona. My average mpg was well in the 50 mpg range with cruise control.
I disagree. You should go over to the prius forums to read up on the technical analysis going on with the egr system.
Waiting for a code to be thrown is definitely not what you want to do with these vehicles.
The general consensus for this engine is to proactively clean the egr system around 100K-120K miles and not more than that under any circumstances.