SL2 99 check engine light On and OFF

[Fermium]

The link below is my previous post that (I think) might related to this problem.

(Won't let me post a link...my post is in this forum with title: SL2 99 check engine light comes code P1404 and P1599)

Couple months ago, my enginer light went on with P1404 so I changed my EGR valve. The engine light went off for a couple of days. Then it went on again for couple of weeks. Then switched off again and yesterday it went on again.

I took the car to the "auto-store" to check my engine light, the person told me there's no code. She suggested maybe my car needs oil change? (It's almost 3500 miles since my last oil change)

So with my new EGR valve (It's the 2nd EGR valve within a year because the P1404 code came on last year so I've already changed the EGR valve once) What do you guys think its the problem?

P.S. I can go check the engine light again to see if there's any new code...

[Signmaster]

Intermittent faults can clear on their own over time, usually based on key on/off or drive cycles. If the EGR malfunctions some times, but not all the time, you have a limited time frame to check it out before the code will clear.

There are also times when the light will come on, but not set a code. I'm not sure if this is a time thing (as in the light must come on for X seconds), or just the nature of some code storing scheme on certain items.