I get the check engine code for a bad EGR valve/system. I have gotten my EGR valve replaced twice and the temp solonoid replaced. Each time the light goes off for maybe a month, then comes back. What else could be causing this problem?

 

On my car, the metal tube from the rear of the intake manifold to the EGR valve was completely clogged with carbon deposits.
Had to physically remove this and clean it out.

 

I had the same exact prob..culprit turned out to be EGR solenoid valve...hope this helps.

 

hope this helps:

0302
Diagnostic Trouble code 0302 points to a problem with the Exhaust Gas Recirculation system. The malfunction is detected by the Engine Control Module when no EGR flow is detected under conditions which call for EGR. Possible causes include:
- The electrical harness or connectors (valve circuit open or shorted)
- The EGR valve is stuck closed
- Weak or dead battery
- The EGR passage is clogged
- Faulty EGR temperature sensor circuit
- A leak somewhere in the exhaust system

The EGR Volume Control Valve may be tested with an ohmmeter. Disconnect the electrical connector. Looking at the connector half which is attached to the EGRVCV with the latch at the 12 o'clock position you will see two rows of three terminals. The top row is numbered 1-3, right to left. The bottom row is numbered 4-6, right to left. Measure the resistance between these terminal pairs:
2 1
2 3
5 4
5 6
... all resistance values should be 20.9-23.1 ohms at 68 degrees F.

Reconnect the EGRVCV connector halves. Turn the ignition switch ON OFF repeatedly. Verify that the EGRVCV shaft moves smoothly forward backward according to the ignition switch position.

The Exhaust Gas Temperature Sensor may be tested with an ohmmeter. The specifications are ...
- at 32 degrees F, 0.68-1.11 Megohms
- at 122 degrees F, 0.09-0.12 Megohms
- at 212 degrees F, 0.017-0.024 Megohms

 

i think there is also a erg sensor also and it could be bad