Q: Check engine light comes and goes with the EGR valve code on a 2.5 Subaru

EGR systems for that vehicle are very complicated and are all ran by a computer. The only way you can figure out what’s wrong is to hire a mechanic. Technicians like ones from YourMechanic have dealer-level scan tools and can scan the system to see what the code is. With proper scan tools they are able to run a bi-directional test of the EGR system to see what has broken down.

Several things need to be checked if they are going bad; the EGR valve, computer control, and wiring. They are pretty complicated systems, the only thing you can do yourself, if you want to try, is that you can take the EGR valve off and clean it with throttle position cleaner. Sometimes the spindle valves get clogged up with carbon. If that doesn’t fix it, it’s time for a mechanic to diagnose the Check Engine Light for you.