Chevrolet Repair: 2000 chevrolet suburban, negative battery cable, chevy suburban

Question
We had a diagnostic done (on our 2000 chevy suburban)at the chevy dealership because our SES light had been on a while. The code came up faulty egr cellinoid (SP). We replaced the egr valve....I guess the cellinoid is in the valve. We were good for about 50 or so miles and then the light came back on. We tried clearing the code by disconnecting the negative battery cable. The light went off for a while then came back on. So.....we then took it back to the dealership, telling them we had just replaced the part they said was faulty. They ran another diagnostic, which showed that the egr was still faulty. So....figuring the part was bad, we replaced it under warranty. We drove the car another 50 or so miles and guess what? The light is back on. What could be wrong with the car? It is getting a little frustrating. Thanks!

Answer
Hi Holly, First there might be a new computer program update for this EGR code. The only way to tell is to do the reprogramming to the computer.
   The other thing it might be is a restricted exhaust pipe that goes to the EGR valve. To check the passages do this...remove the egr valve, now start the engine and you should have exhaust coming out one port and good vacuum on the other port. If this is ok then the other thing could be a bad computer (which is warranty for 8 years or 80k) or bad wiring to the valve.
    I would have them check for a update on the computer after you check the 2 egr ports.

let me know what happens

       Mark