egr valve problem-mystery

So i went into the shop and had them diagnosis my 95 pontiac bonneville se vin k non supercharged and they came across a egr code. Bought a used one from lima auto and worked fine for 4 days, the next day the check engine light came back on, next day it was off for another 4 days and it just repeats this cycle. I'm getting sick of the check engine light when it comes on. what can i do to keep that light off. When the light comes on and when it is off the car runs the same, perfect. what can it be or what do i need to do.

Thanx.

Remove the EGR and clean the valve with throttle body cleaner and make sure the passageway from the engine is also clean. They can plug up and cause issues. Also it is possible that the valve you purchased is bad as well. Also be sure to check the connections to the valve.

ok i cleaned it the passages way leading up to the egr valve is clean. just recently my right turn signal stays on it doesn't flash but stays on constant, then like 4 minutes later it goes off

check for abad bulb