A few weeks ago, check engine light went on and OBD-II scanner read a code - P0401; Exhaust: Gas Recirculation ? insufficient flow detected. I cleaned the EGR valve. The light went off immediately. However, after a week check engine light returned with the same code. The EGR valve appears to hold vacuum. Is this the end of DIY project or is there something else I should try before it goes to a pro? Thank you for your suggestion in advance.
Remove the valve can clean the passages with a coat hanger, especially any external tubes which you may have to replace or ignore depending on your emissions test status…Low flow in the EGR is NOT a life threatening event…
You’re pulling an EGR so you can likely do more. Go buy a $20 repair manual at an auto parts store. It should give you a set of steps to follow to check the system. Caddyman gave you one part of the system - all of the lines and passages running from the valve. I don’t know the camry system but it likely also has some type of sensor and solenoid - those can be tested. A repair manual should tell you how. (You might need a multimeter as well).
For Camry manuals try here: